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3557; Carlsbad Blvd Overhead Bridge Retrofit; Carlsbad Blvd Overhead Bridge Retrofit; 1997-06-11
I LOCAL AGENCY SEISMIC RETROFIT PROGRAM CITY OF CARLSBAD CARLSBAD BOULEVARD OVERHEAD BR. NO. 57C-0134 AS-BUILT ASSESSMENT AND STRATEGY REPORT MARCH 11,1997 REVISED JUNE 11,1997 PREPARED FOR: STATE OF CALIFORNIA BUSINESS, TRANSPORTATION AND HOUSING AGENCY PREPARED BY: MOFFATT & NICHOL ENGINEERS SANTA ANA, CALIFORNIA JN 3807 TABLE OF CONTENTS Page 1.0 INTRODUCTION 1 2.0 BRIDGE DESCRIPTION 1 3.0 GEOTECHNICAL CRITERIA 3 4.0 AS-BUILT ANALYSIS APPROACH 3 5.0 COMPUTER MODEL 4 6.0 STRUCTURAL RESPONSE AND AS-BUILT VULNERABILITIES 5 7.0 RETROFIT STRATEGY 5 8.0 PRELIMINARY COST ESTIMATE 6 9.0 REFERENCES 6 FIGURES FIGURE 1 LOCATION AND VICINITY MAP FIGURE 2 COMPUTER MODEL FIGURE 3 GENERAL PLAN APPENDICES A. GEOTECHNICAL CRITERIA B. AS-BUILT PLANS C. MINUTES OF STRATEGY MEETINGS 1.0 INTRODUCTION The Carlsbad Boulevard Overhead is located on Carlsbad Boulevard at the former Atchinson, Topeka and Santa Fe Railroad Right-of-Way, approximately 0.5 miles north of Carlsbad Village Drive in the City of Carlsbad (Figure 1). The bridge is planned to be retrofitted by the City of Carlsbad in cooperation with Caltrans under the Local Agency Seismic Retrofit Program. San Diego County owns and maintains the bridge and is the lead agency for advertising and constructing the retrofit measures. Caltrans is providing seismic design and funding oversight for the project. A field review was conducted on January 2, 1997, the results of which are documented in a separate report dated January 24, 1997 to which reference should be made. This report includes a summary of the analysis approach, a description of the structural response during the maximum credible earthquake, demand/capacity ratios where appropriate and a summary of the as-built vulnerabilities. The analysis methods and evaluation of the strength and ductility of various bridge components is based on Caltrans Bridge Design Specifications, Memo to Designers 20-4 and Caltrans current retrofit guidelines. Analysis ofthe as-built conditions indicate that retrofitting will be required to several key components of the bridge to prevent collapse. Details of the retrofit measures as modified following the Strategy Meeting of March 18, 1997 are also described in this report. 2.0 BRIDGE DESCRIPTION Original Construction Widening Year Built 1925 1934 Width 37'-8" 18'-6" (13'-8" net) Length 165' Same Spans 5 - simply supported Same Alignment On tangent Same Skew 45° right Same Superstructure Abutments Type Cast-ln-place concrete tee beam Same Diaphragms Concrete diaphragms at all bents and intermediate diaphragms in east bay All diaphragms extended Hinges None Same Type R.C. Frame: Bent cap on three columns R.C. Frame: Bent cap on two columns Wingwalls Cantilever wingwall at both ends of each abutment Same Bearings End diaphragm sits on bent cap Same Shear Keys None None Abutment Foundation Type Spread footing - 3 each Spread footing -2 each Type R.C. Bent cap 2'-3" wide by 3'-3" deep Same Bent Caps Bearings Fixed/Expansion bearing at Bents 3 and 4, Construction joint at Bents 2 and 5. Same Columns Three columns per bent Two columns per bent with Configuration with collision wall between columns collision wall between columns Top and bottom fixed in Fixity transverse direction. Top pinned and bottom fixed in longitudinal direction. Same Size 2' by 2' Same Reinf. 4-1" square bar #3 ties (g 12" Same Infill Wall r thick R.C. Same Collision Wall Size Reinf. r thick R.C. wall between columns Same Size Reinf. #4 @ 18" horiz. and vert, both face Same Bent Foundation Type Size Reinf. Combined footing Same Type Size Reinf. 4' wide continuous Same Type Size Reinf. #5 @ 9" in transverse direction 2 - #5 in longitudinal direction No top mat Same 3.0 GEOTECHNICAL CRITERIA The geotechnical criteria are presented in a separate report prepared by Group Delta Associates. Key items affecting the structural analysis, e.g., seismic criteria, foundation stiffness and capacity, pile capacities, etc., are reproduced in Appendix A for ready reference. The embedded square bent columns have been treated as piles. Single embedded pile analysis was carried out to evaluate the displacements and rotations produced in the pile due to lateral loads and moments applied at the top. This information was used to model the embedded portion of the bent columns. The seismic analysis is based on the ATC-32 ARS curve R3-8 for a 0.5g bed rock acceleration and soil type D corresponding to a magnitude 7.0 event. The maximum passive soil pressure under seismic excitation behind walls 8ft or more in height is taken as 7.7ksf. Per Caltrans recommendation, a linear reduction proportional to wall height has been assumed for walls less than 8ft in height. 4.0 AS-BUILT ANALYSIS APPROACH A dynamic response spectrum analysis was performed using the STAAD III package to obtain the elastic demands for the key components. Capacities were obtained using, RECOL, spread sheets and hand calculations. As-built plans are included in Appendix B for reference. Effective (cracked) section properties were used for the bents for computing force, moment and displacement demands and also for computing displacement ductility. The following material properties were used for evaluating the vulnerabilities: Original Bridge (1925) Widened Bridge (1934) Concrete, f c = 2.45 ksi f c = 2.45 ksi Reinforcement fy = 35 ksi fy = 35 ksi Concrete unit weight w = 0.15 kef The following material properties were used for evaluating the retrofit strategy: Concrete, f c = 3.25 ksi Reinforcement fy = 60 ksi 5.0 COMPUTER MODEL The STAAD III model of the bridge is shown in Figure 2. The superstructure is represented by single beam elements with the appropriate uncracked stiffness in the three directions. The bent columns are similarly represented by single members, but with effective (cracked) stiffness. The effective contributory length of the collision walls has been included in the column properties. Foundation springs are used at the bent footings. Bents 1 & 6 are modeled as abutments with springs and end diaphragms as backwalls. These springs are adjusted to limit the resulting forces to the capacities recommended by the geotechnical criteria. The sections of bent columns embedded in the soil at the ends of the bridge have been modeled as equivalent members with area and stiffness modified to yield the correct displacement and rotation at the mudline. The modified properties have been derived from an embedded pile analysis provided by the geotechnical engineer. 6.0 STRUCTURAL RESPONSE AND AS-BUILT VULNERABILITIES Table 1 shows the as-built demands and capacities for various elements of the bridge. 1. Longitudinal and transverse displacements at the end bents serving as abutments are 14 in. and 6 in. respectively while the longitudinal seat width available is only 9 in., indicating that the bridge will fail by unseating at the ends (Table 1). 2. The connection between the deck girders and the bent caps is inadequate to resist lateral forces. Longitudinal and transverse displacements at the bents after failure of these connections are 12 in. and 3.5 in. respectively which are greater than the 9 in. seat available longitudinally, indicating that an unseating failure can occur at the bents also (Table 1). 3. The flexural capacity of the bent caps is almost equal to that of the bent columns, indicating a possibility of bent cap failure which is not considered acceptable. 4. The flexural D/C ratio exceeds 3.0 at all bent columns. Since the columns are poorly confined, flexural failure of column extremities will occur leading to overall failure (Table 1). 7.0 RETROFIT STRATEGY A summary of the retrofit measures are shown in Figure 3 and consist of the following: 1. Provide infill walls between columns at Bents 2 through 5 to prevent the failure of the columns under transverse loads. 2. Provide side bolsters on the cap beams at both end bents and also interconnect the girder end diaphragms to the bent caps at these locations. This will provide a greater height of soil resistance behind the end bents and restrict displacements. At the same time an unseating failure will be avoided. 3. Provide side bolsters at all intermediate bent caps. Interconnect these bolsters to the girder end diaphragms at all fixed bearings. Incorporate provision for seat extension/shear key at the two intermediate expansion bearing locations. This measure will prevent bent cap failure as well as seating failures. The retrofit strategy described above assumed no liquefaction to occur at the bridge site. If later studies indicate liquefaction is a possibility, then this strategy will require re-evaluation. 8.0 PRELIMINARY COST ESTIMATE The preliminary cost estimate for the retrofit measures indicated is shown in Table 3 and amounts to $354,000. This corresponds to approximately $33 per square foot of the overall bridge plan area. 9.0 REFERENCES 1. Moffatt & Nichol Engineers, Santa Ana, California, Field Review Report, Carlsbad Boulevard Overhead, January 17, 1997. 2. Group Delta Consultants, Inc., Irvine, California, Geotechnical Report. Local Agencv Seismic Retrofit Proiect. Bridge No. 57C-0134 Carlsbad Boulevard Overhead. Carlsbad. California. February 27, 1997. TABLE 1 AS-BUILT ASSESSMENT CARLSBAD BOULEVARD OVERHEAD DEMAND/CAPACITY SUMMARY CASE: AS-BUILT. SWAY TO THE RIGHT (File: CBSB.anI) Bents 1 & 6 released in lateral directions MAX[DL-f1.0L + 0.3T, DL + 0.3 L + 1.0 T ] LOCATION DEFLECTION (in) SHEAR (kip) SHEAR CAPACITY (kip) SHEAR D/C MOMENT (k-ft) MOMENT CAPACITY (k-ft) MOMENT D/C LOCATION Ax Az ^Long Vjran ^Long Vtran VLong Vjran Mlong Mtran MLong Mrran Mung Mtran LOCATION (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) BENT 1 13.84 5.03 0 0 700 0 BENT 2 Column Top 11.55 3.32 65 300 77 77 0.84 3.90 0 1783 228 228 0.00 7.82 BENT 2 Column Bottom 3.92 0.23 67 301 77 77 0.87 3.91 788 1798 228 228 3.46 7.89 BENT 2 Wall Bottom 0.02 0.07 74 302 77 77 0.96 3.92 942 642 228 228 4.13 2.82 BENTS Column Top 10.34 1.61 54 126 77 77 0.70 1.64 0 792 228 228 0.00 3.47 BENTS Column Bottom 3.32 0.10 55 127 77 77 0.71 1.65 800 684 228 228 3.51 3.00 BENTS Wall Bottom 0.01 0.03 61 128 77 77 0.79 1.66 795 272 228 228 3.49 1.19 BENT 4 Column Top 9.07 1.59 53 112 77 77 0.69 1.45 0 735 228 228 0.00 3.22 BENT 4 Column Bottom 2.34 0.07 54 113 77 77 0.70 1.47 700 742 228 228 3.07 3.25 BENT 4 Wall Bottom 0.01 0.03 59 114 77 77 0.77 1.48 223 720 228 228 0.98 3.16 BENTS Column Top 8.00 3.24 66 293 77 77 0.86 3.81 0 1751 228 228 0.00 7.68 BENTS Column Bottom 2.27 0.19 67 295 77 77 0.87 3.83 796 1765 228 228 3.49 7.74 BENTS Wall Bottom 0.02 0.07 73 295 77 77 0.95 3.83 733 591 228 228 3.21 2.59 BENT 6 5.79 5.85 1171 0 1177 0 0.99 ---- Dcexl Shieet 6 TABLE 2 RETROFIT ANALYSIS RESULTS CARLSBAD BOULEVARD OVERHEAD DEMAND/CAPACITY SUMMARY CASE: RETROFIT. SWAY TOWARDS BENT 6 (File: CB-RIIA.anI) Bents 1 & 6 with more longitudinal capacity; Bents 2 through 5 with infill Walls; Footings of Bents 2 through 5 allowed to slide transversely Structure Period = 1.72 sec. MAX [ DL + 1.0 L + 0.3 T, DL + 0.3 L + 1.0 T ] LOCATION DEFLECTION (in) SHEAR (kip) SHEAR CAPACITY (kip) SHEAR D/C MOMENT (k-ft) MOMENT CAPACITY (k-ft) MOMENT D/C Ax Az ^Long Wran ^Long Wran ^Long ^Tran Mtong Mtran MLong Mtran Mtong Mtran 1 2 3 4 5 6 7 8 9 10 11 12 13 14 BENT1 13.13 12.66 0 0 2650 0 . _ _ _ . . . Column BENT 2 Top 13.46 11.28 68 159 77 Large 0.88 -714 -Large Column Bottom 0.02 11.20 84 198 77 Large 1.09 -1034 1340 358 Large 2.89 Column BENT 3 Top 10.98 10.55 60 151 77 Large 0.78 -0'" 740 Large . Column Bottom 0.02 10.47 70 186 77 Large 0.91 -820 1260 346 Large 2.37 Column BENT 4 Top 8.83 11.19 57 166 77 Large 0.74 -862 Large . Column Bottom 0.02 11.11 67 190 77 Large 0.87 -686 1099 335 Large 2.05 Column BENT 5 Top 6.38 12.17 60 176 77 Large 0.78 -806 Large Column Bottom 0.02 12.09 69 209 77 Large 0.90 -597 1254 358 Large 1.67 BENT 6 0.91 14.02 3797 0 3500 0 1.08 -- NOTES: (1) Column tops are pinned in longitudinal direction. H:\3795-02\MA\CARLSBAD\Dcret1 Sfieet 3 TABLE 3 PRELIMINARY COST ESTIMATE LOCAL AGENCY SEISMIC RETROFIT PROGRAM CALRSBAD BOULEVARD OVERHEAD {57C-0134) ITEIVI ITEM UNiT OF ESTIMATED UNIT NO. CODE ITEM MEASURE QUANTITY PRICE TOTAL 1 157550 BRIDGE REMOVAL LS LUMP SUM LUMP SUM $20,000 2 510053 STRUCTURAL CONCRETE, BRIDGE CY 373 350.00 $130,550 3 511106 DRILL AND BOND DOWEL FT 3,866 15.00 $57,990 4 520101 BAR REINFORCING STEEL LB 99,627 0.60 $59,776 (S) _L99Z SUBTOTAL: MOBILIZATION (10%) SUBTOTAL: CONTINGENCIES (20%) BRIDGE COMPONENT TOTAL $268,316 26,832 295,148 58,852 $354,000 PACIFIC OCEAN CARLSBAD BRIDGE LOCATION BR. NO. 57C-0134 VICINITY MAP LOCATION & VICINITY MAP FIGURE 1 Deck Bent Columns Collision ^lls Stiff Members AtDeckJoinfs Embeded Columns End Bents (Typ) — Foundotion Springs — COMPUTER MODEL CARLSBAD BOULEVARD OVERHEAD (BR. NO. 57C-0134) FIGURE 2 I I LEGEND rib di'a ^'' BentJ rn—iTT ufi \i' dent 3 dsnfj Ber)f4 ELEVATION Bents Bents Tup dent's 2 Thru 5 PLAN NOTE; THE CONTRACTOR SHAU VERIFY AU COrfTROLUNG FIELD DIMENSIONS BEFORE ORDERING OR FABRICATING ANY MATERIAL /" .- 50' DESIGN 8T C>«CXX0 LOAD FACTOR DESIGN LiVE LOAOmCi HS20-44 AND ALTERNATIVE AND PERMIT DESIGN LOAD OCIIGM OvtMIGKT DETAILS •T LAYOUT sr CMCCiCO OCIIGM OvtMIGKT QUANTITIES 8T 0«CxED SPECIflCATlCHS o <B> <£> INDICATES EXISTING STRUCTURE INDICATES NEW CONSTRUCTION INDICATES LOCATION OF WORK BENT RETROFIT (INFILL WALLS) BENT CAP RETROFIT FOR BENTS 3 & 4 (SIDE BOLSTER & SHEAR KEY/SEAT EXTENSION) BENT CAP RETROFIT FOR BENTS 2 & 5 (SIDE BOLSTER) BENT CAP RETROFIT FOR BENTS 1 & 6 (SIDE BOLSTER / SEAT EXTENSION) POST MILES TOTAL PROJECT SHEET NO. TOTAL SHEETS REGISTERED CIVIL ENGINEER PLANS APPROVAL OATE SPONSORING AGENCY PREPARED FOR THE STATE OF CALIFORNIA QEPARThENT OF TRANSPORTATION Oft ICi NAL SCALE IN lNCHE?j FOR SEDUCED PLANS THE STATE OF CAUFORNIA OR ITS OFFICERS OR AGENTS SHALL NOT BE RESPONSIBLE FOR THE ACCURACY OR COMPLETENESS OF ELECTRONIC COPIES OF THIS PUN SHEET. Mi 4.0H /•8"t [ 1 i-ii ^ ? Roadway t \ I I '<' ^ '1' < t PART ELSVATION BENTS 2 TH-RU ^ SECTION (A: 3/16"= I'-O" nWjCCT EMOINCUt cu EA "aSTocE'TIor 57C-0134 POST MILE CARLSBAD BOULEVARD OVERHEAD DISREGARD PRINTS BEARING EARLIER REVISION DATES— GENERAL PLAN REVISION DATES IPRELIMINART M ANLY) -sr- FIGURE 3 I 'if'K ' ^ 1 / - ^ - • / ->• : '- / \ < fl f ' .P'', '-"•:'-". '.' " '. • • -- I i-r ''•. , APPENDIX A GEOTECHNIGAL CRITERIA TABLE 1 SUMMARY OF PRELIMINARY SEISMIC, GEOLOGIC, AND FOUNDATION INFORMATION Bridge Name: Bridge No.: Carlsbad Overhead 57C-134 Geologic Data: Based on Log of test Borings for Elm Avenue Undercrossing and the Las Flores Overcrossing bridges, soils consist of compact to dense sands and silty sands. GWS: No groundwater data is available at the site. In Elm Avenue bridge site, groundwater is about 3 to 6 ft below the surface, while in Las Flores Drive bridge site, groundwater is about 42 to 45 ft below the surface. Earthquake Data : Lat. 39° 9.8'N Long. 117° 21.2' W Fault: Offshore Zone of Deformation (Rose Canyon Fault) Magnitude: 7.0 Distance to Site from Fault: Horizontal Bedrock Acceleration (max): 0.45 g SOIL PROFILE TYPE FOR ARS CURVES (ATC-32): Figure R3-8 (A) (B) (C) (^^IDT) (E) (F) Liquefaction Potential: Low_ Med High. "As-Built" Foundation : Piles: Not Used Spread Footings: Used Pile Type(s): N/A Allowable Bearing Pressures: N/R Design Load: N/A Allowable Bearing Pressures: N/R Est. Ultimate Compression Load for Retrofit: N/A Est. Ultimate Uplift for Retrofit Design: N/A Scour Potential: Yes No Remarks Additional Drilling Required: Yes No PRELIMINARY GEOTECHNICAL REPORT SEISMIC RETROFIT PROJECT BRIDGE NO. 57C-134 CARLSBAD OVERHEAD SAN DIEGO COUNTY, CALIFORNIA 1.0 GENERAL 1.1 Background The County of San Diego is considering the Carlsbad Overhead (Bridge No. 57C-134) for seismic retrofit. The bridge site is shown in Figure 1. The bridge is located along Carlsbad Boulevard approximately 1.0 km (0.6 mi.) northwesterly of Elm Avenue. 1.2 Existing Design Infomiation We have reviewed plans of the Carlsbad Overhead provided to us by Moffatt & Nichol Engineers. The pertinent bridge plans used in our study are presented in Appendix A. The existing bridge was buih in 1925 by Califomia Department of Transportation, Division of Structures under Contract No. M-111. In 1935, the bridge was widened. The bridge has five spans with individual span lengths varying from 8.2 to 13.7 m (27 to 45 ft). The total length of the bridge is 50.3 m (165 ft) and the bridge is skewed to the right by 454 degrees. The net width of the bridge is 13.7 m (45 ft) with an overall width of 15.7 m (51.5 ft). The bridge consists of five simple CIP/RC "T" beam girder spans supported by two closed-end backfilled reinforced concrete strutted column bent abutments and four reinforced concrete column bents. All bridge foundations are shallow foundations. 1.3 Scope of Work In general, the purpose of our investigation was to review the existing foundation data and to develop parameters for the seismic retrofit evaluation. Our scope of work consisted of: a brief site visit and reconnaissance, review of as-built plans, evaluation of geotechnical foundation parameters, and preparation of this report. Specifically, we assessed the following geotechnical information: • Spring constants for spread footings, • Lateral resistance for abutment walls and spread footings, • Ultimate bearing capacity, and • Liquefaction potential C:\PR0JECTS\M0FFATT\RETR0FnABR57C 134.DOC Carlsbad Overhead GDC Project No. I-111 Moffatt & Nichol Engineers Page 2 1.4 Pertinent Reports and Investigations Our imderstanding of this project is based on discussions with Moffatt and Nichol Engineers, our site visit, and our review of the available plans and bridge summary report. A list of references reviewed is provided in Section 5.0. 2.0 PRELIMINARY SEISMIC, GEOLOGIC, AND FOUNDATION DATA A summary of existing conditions, and seismic design considerations is presented in Table 1. Additional as-built foundation details are summarized in Table 2. 3.0 DISCUSSION AND RECOMMENDATIONS 3.1 Soil Conditions No Log of Test Boring was provided for this bridge. However, Logs of Test Borings from the Elm Avenue Undercrossing and the Las Flores Drive Overcrossing bridges were available (see Appendix B). These bridges are within approximately 1.1 km (0.7 mi.) from the subject bridge. The subsurface investigation at the Elm Avenue Undercrossing consisted of three driven cone borings. The depths of exploration ranged from Elevation 23.6 to 18.6 m (75.5 to 61 ft). The soils encountered consisted of silty sands, sands, and sandy gravel. Penetration resistances in excess of 100 are reported in the logs. The subsurface investigation at the Las Flores Drive Overcrossing consisted of advancing two 2.5-cm (1-in.) sample borings. The zone of exploration was from Elevation 23.8 to 8.5 m (78 to 28 ft). The soils encountered included sands and silty sands. The penetration resistances of the 2.5-cm (1-in.) sample borings varied between 100 to 4000 blows per foot. Based on our site visit at the Carlsbad Overhead, we noted that exposed soils consisted of formational soils comprised of cemented sands and sandstones. No evidence of seepage was noted. The approximate ground surface elevation undemeath the bridge is 7.3 m (24 ft). For purposes of our study, we assumed that the subsurface soils are generally comprised of compact to dense sands and silty sands. We assumed the soils had an equivalent standard penetration test (SPT) blowcount of 30 and average total unit weight of 1.922 kg/m'(120pcf). 3.2 Groundwater Conditions Groundwater was encountered in Elm Avenue bridge site between Elevations 21 and 21.8 m (69 and 71.5 ft) or approximately 0.9 to 1.8 m (3 to 6 ft) below the ground surface. In Las Flores Drive bridge site, groundwater was reported to be between Elevations 12.8 to 14.0 m (42 to 46 ft) or approximately 9.45 to 10.4 m (31 to 34 ft) below the ground C:\PR0JECTS\M0FFATnRETR0FIlABR57C 134.D0C Carlsbad Overhead GDC Project No. I-111 Moffatt & Nichol Engineers Page 3 surface. Therefore, a potential for shallow groimdwater at the Carlsbad Overhead bridge site exists. 3.3 Seisniic Parameters 33.1 Response Spectra It is our understanding that the Department of Transportation (Caltrans), Engineering Service Center has not developed a recommended response spectra for the Carlsbad Overhead Bridge. We recommend using a bedrock acceleration of 0.45g and ATC-32 Figure R3-8 for response spectra. Our response spectra recommendations are based on our review of the faults in the general area of the bridge as well as DMG OPEN-FILE-REPORT 92-1. According to our review, the controlling fault for the Carlsbad Overhead Bridge is the Offshore Zone of Deformation (Rose Canyon Fault). The magnitude associated with this fault zone is reported to be 7. The estimated bedrock acceleration for the Carlsbad Overhead site is approximately 0.45 g. We characterized the subsurface soil profile as Type D per ATC-32 criteria. 3.3.2 Spread Footings All foundations are supported on spread footings. A summary of as-built foundation dimensions and characteristics are presented in Table 2. The ultimate bearing capacity of the spread footings was estimated by assuming a fiiction angle of 32 degrees. Spring constants for the spread footings were estimated by using low strain shear modulus values based on energy corrected blow count and published correlation by Sykora (1987) shown in Figure 2 and dynamic spring constant formulas for rigid footings. The calculated spring constants are low strain values and are applicable at small displacements. They should be considered as initial values for starting the analysis. If calculated displacements using the spring constants are such that the ultimate bearing capacity or lateral resistance is exceeded, softer springs should be used so that the limiting values of bearing capacity and ultimate lateral resistance are not exceeded. Ultimate lateral capacity of spread footings is a ftinction of both sliding resistance and passive soil resistance. In our recommendations, we have provided design parameters for both sliding resistance and the ultimate passive soil resistance acting on the side of the foundation. The ultimate passive soil resistance does not include any contribution from sliding. In addition, for passive resistance of spread footings, we assumed that the footing excavations are backfilled with compacted granular fill. The recommended foundation capacities and spring design parameters are summarized in Tables 3 and 4. C:\PR0JECTS\M0FFAmRETR0FmBR57C 134.DOC Carlsbad Overhead GDC Project No. I-111 Moffatt & Nichol Engineers Page 4 3.3.3 Pile Foundations Pile foundations were not used for this bridge. 3.3.4 Lateral Load Pile Response of Outer Bent Columns At the request of Moffatt and Nichol, we evaluated the lateral load pile response of the outer bent columns of the bridge using the fmite difference computer program PILED/G (GEOSOFT, 1988). The program uses non-linear (p-y) soil resistance-lateral deflection curves to represent soil characteristics. These columns extended from the bridge deck to a depth of 1.8 to 3 m (6 to 10 ft) below the ground to the top of the footings. The columns were comprised of 0.6-m (2-ft) square reinforced concrete columns. As requested by Moffatt and Nichol, we applied the lateral load at the ground surface, considered both free and fixed head conditions, and used 40 percent of the EI of the column. We understand that Moffatt and Nichol models the bridge and bridge columns as structural elements with the buried portion of the column and associated foundations modeled as an equivalent stmctural element. The characteristics of this equivalent element are developed from the results of our analyses. Due to the relative shallowness of the column embedments, the lateral load response of the columns corresponded to the behavior of a short, rigid pile. The variation of pile deflection, pile moment, and shear with depth for the cases evaluated are presented as Figures 3 through 8. A summary of the variation of pile displacement at the ground surface and maximum pile moment with applied load is presented in Table 5. 3.3.5 Ultimate Lateral Capacity of Abutment Walls The ultimate lateral capacity of an abutment wall is a fimction of the height of the abutment wall which is acted on by the passive soil pressure on the backfill. We have provided recommendations for the average ultimate passive soil pressure acting on the abutment wall. This dynamic value is based on a passive pressure coefficient of 10.3 for the compacted backfill providing an average pressure of 239 kPa (5 ksf) for an 2.4-m (8- ft) high wall. The ultimate static lateral pressure was increased by (1/0.65) to account for short-term dynamic loading and use of peak groimd acceleration. The ultimate lateral capacity for wall heights 2.4 m (8 ft) and above should be taken as 369 kPa (7.7 ksf). For wall heights less than 2.4 m (8 ft), we recommend that the ultimate capacity be obtained by multiplying 369 kPa (7.7 ksf) value with the ratio (H/2.4) where H is the wall height in meters, {(H/8) for H in feet}. Passive pressures are mobilized when the deflection ofthe wall reaches 0.02 H meters (or feet), where H is the wall height in meters (or feet). The estimated abutment wall stiffness then becomes the ultimate lateral capacity of the wall divided by the wall displacement. 3.4 Liquefaction Potential Groundwater data for the site is unavailable. Although there is a potential for shallow groundwater at the site, based on borings at nearby bridge sites, our preliminary estimate C;\PR0JECTS\M0FFAmRETR0FmBR57C134.D0C Carlsbad Overhead GDC Project No. I-111 Moffatt & Nichol Engineers Page 5 of liquefaction potential for Carlsbad Overhead is low. However, since there is no Log of Test Borings available for this bridge, we recommend drilling two borings and conducting additional liquefaction analysis based on the results of the new subsurface data. 4.0 LIMITATIONS No field investigation was performed at the sites. In view of past grading and the general geology of the area, possibility of different conditions can not be discounted. It is the responsibility of the owner to bring any deviations or unexpected conditions observed during constmction to the attention of the Geotechnical Engineer. In this way, any required supplemental recommendations can be made with a minimum of delay. This report was prepared in accordance with generally accepted geotechnical engineering principles and practice. The professional engineering work and judgments presented in this report meet the standard of care of our profession at this time. No other warranty, expressed or implied, is made. 5.0 REFERENCES Available plans as follows: State of Califomia, Califomia Highway Commission, "Bridge over Atchison Topeka & Santa Fe RY. Near Carlsbad-Sta. 478-F30.69, San Diego County": General Plans, abutment details, bent details, and miscellaneous plans dated 1925. State of Califomia, Califomia Highway Commission, "Widening of Bridge over Atchison Topeka & Santa Fe RY. Near Carlsbad-Sta. 478-1-30.69, San Diego County": General Plans and miscellaneous details dated 1934. Log of Test Borings for "Elm Avenue Undercrossing". Log of Test Borings for "Las Flores Drive Overcrossing". References: Applied Technology Council, ATC-32, 1996, "Improved Seismic Design Criteria for Califomia Bridges: Provisional Recommendations". Arya, Suresh; O'Neill, Michael, and Pincus, George, 1979, "Design of Stmcmres for Vibrating Machines," Gulf Publishing Company, Houston, 1979, pp.191. Califomia Department of Conservation, Division of Mines and Geology, 1992, "Peak Acceleration From Maximum Credible Earthquakes in Califomia (Rock and Stiff-Soil Sites)", DMG OPEN-FILE REPORT 92-1. C:\PROJECTS\MOFFATT\RETROFI'RBR57C134.DOC Carlsbad Overhead GDC Project No. I-111 Moffatt & Nichol Engineers Page 6 Department of Transportation, Engineermg Service Center, Office of Stmctural Foundations-MS #5, Stmcture Foundations Branch, 1996, "Acceleration Response Spectra for Local Agency Seismic Retrofit Bridges", Memorandum, August 13, 1996, Local Agency Seismic Retrofit Contract No. 59Y025, EA 53-965100. Earth Technology Corporation, 1986, Seismic Design of Highway Bridge Foundations, A Report Prepared for the U.S. Department of Transportation, Report No. FHWA/RD-86/101. GEOSOFT, 1988, "PILED/G, Laterally Loaded Drilled Piers and Piles", A Finite Difference Program for Calculating Lateral Load Response of Piles, 1442 Lincoln Avenue, Ste. 146, Orange, CA 92667. State of Califomia Department of Transportation, 1990, Bridge Report, Carlsbad Overhead (Carisbad Boulevard - 0.6 miles northwesterly of Ehn Avenue, FAU S352)" May 22, 1990. Sykora, D., 1987, "Examination of Existing Shear Wave Velocity and Shear Modulus Correlations in Soils", U.S. Department of the Army, Waterways Experiment Station, Corps of Engineers. C:\PR0JECTS\M0FFAmRETR0FmBR57C 134.D0C TABLE 1 SUMMARY OF PRELIMINARY SEISMIC, GEOLOGIC, AND FOUNDATION INFORMATION Bridge Name: Bridge No.: Carlsbad Overhead 57C-134 Geologic Data: No Log of Test Borings was available for this bridge. Based on Log of Test Borings for Elm Avenue Undercrossing and the Las Flores Overcrossing bridges located approximately 1.1 km fi-om the subject bridge, soils consist of compact to dense sands and silty sands. GWS: No groundwater data is available at the site. In Elm Avenue bridge site, groundwater is about 3 to 6 ft below the surface, while in Las Flores Drive bridge site, groundwater is about 42 to 45 ft below the surface. Earthquake Data : Fault: Offshore Zone of Deformation (Rose Canyon Fault) Distance to Site from Fault: 7 km Horizontal Bedrock Acceleration (max): 0.45 g Lat. 39° 9.8' N Long. 117°2L2' W Magnitude: 7.0 SOIL PROFILE TYPE FOR ARS CURVES (ATC-32): Figure R3-8 (A) (B) (C) Liquefaction Potential: Low x * Med (E) (F) High. "As-Built" Foundation : See Table 2 Piles: Not Used Spread Footings: Used Pile Type(s): N/A Allowable Bearing Pressures: Design Load: N/A See Tables 3 and 4 Est. Ultimate Compression Load for Retrofit: N/A Est. Ultimate Uplift for Retrofit Design: N/A Scour Potential Yes No Remarks : * The liquefaction potential for this bridge was based on limited subsurface soil and groundwater data. Ifthe conditions considered in the estimate differ from the actual estimate, the liquefaction potential for the site may be high. Additional Drilling Required: Yes ,\JM^ No Kul Bhushan, Ph.D., G.E. C:\PROJECTS\MOFFATnRETROFIT\BR57CI34.DOC 2.0 I I 0.7q(0.7g) I I i I SOIL PROFILE TYPE D MAGNITUDE: 7.25±0.25 Note: Peok ground occelerotion volues not in porentheses are for rock (Soil Profile Type S) ond peak ground acceleration values in porentheses ore for Soil Profile Type D. Curve For Carlsbad OH (045g) . PERIOD (sec) 50 40 Curve For Carlsbad QH, msg) 0.7Q (0.7g) PERIOD (sec) Figure R3-8 Proposed ARS curves for soil type D (Af = 7.25 ± 0.25) ATC-32 BDS Recommendations, Sednon 3: Loads 37 TABLE 2: SUMMARY OF AS-BUILT FOUNDATION CHARACTERISTICS Bridge Name: Carlsbad Overhead Bridge Number: 570-134 Location Spread Footings or Pile Caps Pile Foundations Comments Location No. of Elements Dimensions (ft.) b.o.f. elev. (fi.) q allow (KsO Type Numlier Q allow (kips) Pile Penetration Pite Tip Elev. (ft.) Comments Location No. of Elements L B T D b.o.f. elev. (fi.) q allow (KsO Type Total Vertical Batter Q allow (kips) Pile Penetration Pite Tip Elev. (ft.) Comments Bent 1 4 5.0 5.0 2.0 4 to 9 30 to 33 N/R N/A N/A N/A N/A N/A N/A N/A Bent 2 53.5 4.0 2.0 5 to 7 17 N/R N/A N/A N/A N/A N/A N/A N/A Benl 3 , 535 40 2.0 Sto 7 17 tm N/A N/A N/A N/A N/A N/A N/A Bent 4 1 53.5 4.0 20 5 to 7 19 N/R N/A N/A N/A N/A N/A N/A N/A Bent 5 1 53.5 4.0 2.0 Sto 7 18.5 N/R N/A N/A N/A N/A N/A N/A N/A Benl 6 6 50 5.0 20 3 to 5 24 to 25 N/R N/A N/A N/A N/A N/A N/A N/A NOTES 1 2 3 4 5 6 7 8 9 10 11 f2 f3 fS fS Local Agency Seismic Retrofit Project GDC ProjectNo. 1-111 Group Delta Consultants 5/29/97 NOTES FOR TABLE 2: SUMMARY OF AS-BUILT FOUNDATION CHARACTERISTICS 1. Location refers to the foundation element for which the informalion is provided (e.g. Abutment 1 or Bent 2). 2. No. of Elements refers to the number of spread footing elements for the specified location. Example, ifthe no. of elements is 2, there are two spread footings for the location. 3. L refers to the length ofthe spread footing or pile cap. The length of the foundation is the dimension perpendicular to the longitudinal axis of the bridge. If there is more than one element, a range of the lengths is provided. 4. B refers to the width of the spread footing or pile cap. The width of the foundation is the dimension perpendicular to the transverse axis of the bridge. If there are more than one element, a range of the lengths are provided. 5. T refers to the thickness of the spread footing of pile cap. 6. D refers to the embedment depth of the spread footing or pile cap as measured from the minimum ground surface to the bottom of the footing or pile cap. 7. b.o.f. elev. refers to the estimated or reported elevation corresponding to the bottom of the spread footing or pile cap. 8- q«ii«w refers to the plan reported allowable bearing pressure. If this values could not be obtained from the plans, N/R (Not Reported) is shovra. If there are no spread footings, N/A (Not Applicable) is shown. 9. Type refers to the reported type of pile foundation used for the bridge. 10. Total refers to the total number of pile foundation elements in the specified pile cap. If the number could not be accurately confirmed, N/R (Not Reported) is shown. If there are no pile foundations. N/A (Not Applicable) is shown. 11. Vertical refers to number of pile foundation elements which are vertical. If the number could not be accurately determined, N/R (Not Reported) is shown. If there are no pile foundations, N/A (Not Applicable) is shown. 12. Batter refers to number of pile foundation elements which are battered. If the number could not be accurately determined, N/R (Not Reported) is shown. If there are no pile foundations, N/A (Not Applicable) is shown. 13. Q.„„„ refers to the plan reported design capacity of the pile foundation element. If this values could not be obtained from the plans, N/R (Not Reported) is shown. If there are no pile foundations, N/A (Not Applicable) is shown. 14. Pile Penetration refers to the length of pile foundation in the ground. If this information could not be obtained from the plans, N/R (Not Reported) is shown. If the bridge was supported on spread footings, N/A (Not Applicable) is shown. 15. Pile Tip Elev. (ft) refers to the reported average pile tip elevation of die pile foundation. If this information could not be obtained from the plans, N/R (Not Reported) is shown. If the bridge was supported on spread footings, N/A (Not Applicable) is shown. 16. This column is for additional comments. TABLE 3: SUMMARY OF RECOMMENDED BRIDGE FOUNDATION CAPACITIES Bridge Name: Carlsbad Overhead Bridge Number: 57C-134 Location Average Abutment Wall Pressure Foundations * Lateral Resistance of Footing or Pile Cap Location p avg (ksf) ^ mob (inches) Type Q ult (kips) or q ult (ksO Q up (kips) A axial (inches) Pult (kips) A lateral (inches) Total Passive Force (kips) Sliding Coefficient Location H>8fl. H<8ft. ^ mob (inches) Type Q ult (kips) or q ult (ksO Q up (kips) A axial (inches) Pult (kips) A lateral (inches) Transverse Longitudinal Sliding Coefficient Bent 1 7.7 7.7 X (H/8) 0.02*H Spread Footing 20 65 N/A N/A N/A 48 48 0.45 Bent 2 N/A N/A N/A Spread Footing 15 140 N/A N/A N/A 38 600 0.45 Bent 3 N/A N/A N/A Spread Footing 15 140 N/A N/A N/A 38 600 0.45 Bent 4 N/A N/A N/A Spread Footing 15 140 N/A N/A N/A 38 600 0.45 Bents N/A N/A N/A Spread Footing 15 140 N/A N/A N/A 38 600 0.45 Bent 6 7.7 7.7 X (H/8) 0.02*H Spread Footing 20 60 N/A N/A N/A 48 48 0.45 Notes 1 2 3 4 5 6 7 8 9 fO 11 12 13 ' The foundation capacities shown are our best estimates. Since the Log of Test Borings for this bridge is not available, the actual foundation capacities may vary by 50 %. Local Agency Seismic Retrofit Project GDC Project No. 1-111 Group Delta Consultants 5/29/97 NOTES FOR TABLE 3: SUMMARY OF RECOMMENDED FOUNDATION CAPACITIES 1. Location refers to the foundation element for which the infonnation is provided. For example, if the location is Abutment 1, the information provided is for the abutment. 2. The recommended average ultimate abutment wall pressure for wall heights greater than or equal to eight feet. 3. Ifthe wall height is less than 8 feet, then the average abutment wall pressure is computed as follows: Psvg^^.T X (H/8). This equation prorates the maximum wall pressure by the wall height divided by 8 feet. 4. This column represents the wall displacement necessary to mobilize tiie average abutment wall pressure. This displacement can be used with the wall pressure to compute the equivalent abutment stif&iess. 5. Type refers to tiie foundation type at tiie specified foundation location. For example, Spread Footing refers to spread footings and Pile refers to pile foundations. 6. Ifthe foundation type is specified as Spread Footing then the reported value refers to q„„ which is the estimated ultimate bearing capacity of the spread footing. Conversely, if the foundation type is pile, the value refers to Q„„ which is the estimated ultimate axial capacity of a single pile foundation element. The q„„ values shovm apply for vertical loads only and do not take into account lateral loads. For spread footings with lateral loads ranging from 20 to 40 % of tiie total vertical loads, approximately 20 to 60 % reduction in q^, values are anticipated. 7. If tiie foundation type is specified as spread footing, tiien tiie ultimate uplift capacity of the footing includes the weight of the footing and tiie soil above the footing. For a pile foundation tiie value refers to the estimated ultimate uplift capacity of a single pile foundation element. 8. The value specified is the axial displacement necessary to mobilize the ultimate pile capacity. 9. P„„ refers to tiie ultimate lateral capacity of a single pile for tiie corresponding specified lateral displacement. 10. This column refers to the lateral pile displacement necessary to mobilize the ultimate lateral capacity of the pile. 11. This value corresponds to the passive resisting force developed on the specified side of the spread footing or pile cap. This value does not include any lateral resistance from piles. This values is assumed to be fully mobilized under a displacement equal to approximately 2 percent of the foundation thickness. 12. This value corresponds to the passive resisting force developed on tiie specified side of the spread footing or pile cap. This value does not include any lateral resistance from piles. This values is assumed to be ftilly mobilized under a displacement equal to approximately 2 percent of the foundation thickness. 13. This value corresponds to the coefficient of friction along tiie bottom ofthe spread footing. This value is assumed to be fully mobilized under a displacement equal to approximately 2 percent of the foundation thickness. For pile foundation, N/A (Not Applicable) is shown. TABLE 4: SUMMARY OF RECOMMENDED FOUNDATION STIFFNESS Bridge Name: Carlsbad Overhead Bridge Number: 570-134 Location Spread Footing or Pile Cap Stiffness Single Pile or CIDH Comments Location Vertical (kips/inch) HorizonI al (kips/in) Rocking (kip*inch/rad) Torsional (kip*inch/rad) Vertical (kips/inch) Horizontal (kips/inch) Comments Location Vertical (kips/inch) Transverse Longitudinal Transv. Axis Long. Axis Torsional (kip*inch/rad) Vertical (kips/inch) Horizontal (kips/inch) Comments Bent 1 8.40E+03 1.10E+04 1.10E+04 8.50E+06 8.50E+06 5.40E+06 N/A N/A Bent 2 2.60E+04 2.10E+04 2.10E+04 1.40E+07 1.60E+09 8.20E+08 N/A N/A Bent 3 2.60E+04 2.10E+04 2.10E+04 1.40E+07 1.60E+09 8.20E+08 N/A N/A Bent 4 2.60E+04 2.10E+04 2.10E+04 1.40E+07 1.60E+09 8.20E+08 N/A N/A Bents 2.60E+04 2.10E+04 2.10E+04 1.40E+07 1.60E+09 8.20E+08 N/A N/A Bent 6 8.40E+03 1.10E+04 1.10E+04 8.50E+06 8.50E+06 5.40E+06 N/A N/A Wofes 1 2 2 2 2 2 2 3 4 5 Local Agency Seismic Retrofit Project GDC Project No. 1-111 Group Delta Consultants 5/29/97 I I I NOTES FOR TABLE 4: SUMMARY OF RECOMMENDED FOUNDATION STIFFNESS !.• Location refers to the foundation element for which the information is provided. For example, if the location is Abutment 1, the information provided is for the abutment. 2. The recommended foundation stif&iesses are for small-strain shear modulus values and dynamic spring constant formulas for rigid footings. The calculated spring constants are small strain values and are applicable for small foundation displacements. If the calculated displacements using the spring constants are such that the ultimate bearing and lateral resistances are exceeded, softer springs should be used. Foundation displacements which would generate shear strains on the order of a few percent would result in a reduction of stif&iess on the order of 5 to 10 percent. 3. The spring stif&iess for the axial direction of the pile is based upon tiie ultimate pile capacity and the displacement necessary reach the ultimate capacity. 4. The spring stiffiiess for the lateral direction is based upon our lateral load analyses for vertical piles. The stiffness is based on the ultimate lateral load divided by the lateral displacement needed to reach tiie ultimate value. For battered piles, the horizontal component of the axial stifftiess can be used instead. 5. This column is for appropriate comments. TABLE 5: SUMMARY OF LATERAL LOAD VS PILE DEFLECTION AND MAXIMUM MOMENT Bridge Name: Carlsbad Overhead Bridge Number: 57C-134 Location: Bent Bent Bent Bent Bent Bent Head Condition: Free Head Free Head Free Head Free Head Free Head Free Head Length: 10ft 10ft 8ft 8ft 8ft 8ft Lateral Load (Ibs) Deflection at Ground Surface (inches) Maximum Moment (ft-kips) Deflection at Ground Surface (inches) Maximum Moment (ft-kips) Deflection at Ground Surface (inches) Maximum Moment (ft-kips) 2,000 0.01 5 0.02 4 0.03 3 5.000 0.04 13 0.05 11 0.12 9 10,000 0.09 27 0.16 24 1.39 20 12,000 N/A N/A N/A N/A 2.89 24 15,000 N/A N/A 0.58 40 N/A N/A 20,000 0.34 63 2.24 52 N/A N/A 25,000 N/A N/A 32.06 70 N/A N/A 30,000 1.97 96 N/A N/A N/A N/A 35,000 4.13 115 N/A N/A N/A N/A Notes 1 2 3 2 3 2 3 Location: Bent Bent Bent Bent Bent Bent Head Condition: Fixed Head Fixed Head Fixed Head Fixed Head Fixed Head Fixed Head Length: 10ft 10ft 8ft 8ft 6ft 6ft Lateral Load (Ibs) Deflection at Ground Surface (inches) Maximum Moment (ft-kips) Deflection at Ground Surface (inches) Maximum Moment (ft-klps) Deflection at Ground Surface (inches) Maximum Moment (ft-kips) 2,000 0.01 -7 0.01 -8 0.01 -7 5,000 0.01 -18 0.01 -19 0.01 -18 10,000 0.03 -36 0.03 -39 0.03 -37 12,000 N/A N/A N/A N/A N/A N/A 15,000 N/A N/A 0.04 -60 0.05 -57 20,000 0.06 -78 0.06 -83 0.07 -77 25,000 N/A N/A 0.08 -107 0.10 -98 30,000 0.10 -125 N/A N/A N/A N/A 35,000 0.13 -151 N/A N/A N/A N/A Notes 1 2 3 2 3 2 3 Local Agency Seismic Retrofit Project GDC Project No. 1-111 Group Delta Consultants 5/29/97 NOTES FOR TABLE 5: SUMMARY OF LATERAL LOAD VS PILE DEFLECTION AND MAXIMUM MOMENT 1. Lateral pile load applied at the ground surface. 2. Pile head deflection produced by the applied lateral load. 3. Maximum moment in pile produced by the applied lateral pile load. -.2 12 * i J Mr i T r -10.0 0. DEFLECTION TH INCH CASE SYMBOL 10.0 -.4 0. MOMENT IN KIP-FT X 1000 SHEAR IN KIP X 100 DESCRIPTION .4 1 O 2 • a A 4 0 5 6 • 57C-134. Outer Benta, Free. L 10. P 2000 lb P 5000 Ihs P 10,000 lha P 20.000 Iba P 30,000 lbs P 35.000 Iba nil CARLSBAD OVERHEAD (BRIDGE NO. 570-134) Group Delta Consultants DEFLECTION. MOMENT, AND SHEAR VS DEPTH FIGURE 3 Q -40.0 0. DEFUKTION IN INCH CASE SYMBOL 4-0.0 -.4 0. MOMENT IN KIP-FT X 1000 SHEAR IN KIP X 100 DESCRIPTION .4 1 2 3 4 5 6 O • A 0 it 57C-134. Outer Benta, Free. L 8 ft, P 2000 lb P SOOO lbs P 10.000 Iba P 15.000 lbs P 20,000 lbs P 25.000 lbs nil Group Delta Consultants CARLSBAD OVERHEAD (BRIDGE NO. 57c-134) DEFLECTION. MOMENT. AND SHEAR VS DEPTH FIGURE 4 -.1 5 H Q -4.0 0. DEFLECTION Df INCH CASE SYMBOL 4.0 -.2 0. MOMENT IN HP-IT X 1000 SHEAR Df KIP X 100 DESCRIPTION 1 2 3 4 O • A 0 57C-134. Outer Benta. Free. L P SOOO Iba P 10,000 Iba P 12.000 Iba 6 ft, P 2000 lb nil CARLSBAD OVERHEAD (BRIDGE NO. 57C-134) Group Delta Consultants DEFLECTION. MOMENT. AND SHEAR VS DEPTH FIGURE 5 -.2 0. .2 Q 12 nr ' • • 1 \\\ t -.2 0. DEFLECTION IN INCH CASE SYMBOL .2 -.4 0. MOMENT IN KIP-FT X 1000 SHEAR IN KIP X 100 DESCRIPTION .4 1 2 3 4 5 6 O • A 0 57C-134. Outer Benta. Fixed L 10. P 2000 lb P SOOO Iba P 10.000 Iba P 20.000 Iba P 30.000 lbs P 35,000 lbs nil CARLSBAD OVERHEAD (BRIDGE NO. 57C-134) Group Delta Consultants DEFLECTION. MOMENT. AND SHEAR VS DEPTH FIGURE 6 -.2 Q 10 12 Kl 1 ^ 1 f -.1 0. DEFLECTION IN INCH CASE SYMBOL .1 -.4 0. MOMENT IN KD'-FT X 1000 SHEAR Df KEP X 100 DESCRIPTION 1 2 3 4 5 6 O • A 0 57C-134. Outer Benta. Rxed. L 8 fL P 2000 lb P 5000 Iba P 10,000 Iba P 15.000 lbs P 20,000 Iba P 25.000 Iba nil CARLSBAD OVERHEAD (BRIDGE NO. 57C-134) Group Delta Consultants DEFLECTION. MOMENT, AND SHEAR VS DEPTH FIGURE 7 -.1 .1 13 H Q -.2 0. DEFIi:cnON Df INCH CASE SYMBOL 1 2 3 4 5 6 O • A 0 .2 -.4 0. .4 MOMENT IN HP-FT X 1000 SHEAR Df KIP X 100 DESCRIPTION 57C-134. Outer Benta. Fired. L 6 fL P 2000 lb P 5000 lbs P 10.000 Iba P 15.000 lbs P 20,000 Iba P 25.000 Iba nil CARLSBAD OVERHEAD (BRIDGE NO. 57C-134) Group Delta Consultants DEFLECTION. MOMENT. AND SHEAR VS DEPTH FIGURE 8 ••• - ^A f v'' - \^ - '- . J ^ - ' ' ~- yy • > .vV - ^' ^ - > ' -'• '_ . -If' ^ y.. . "-^^ v',.-v ^A 1 yi-y-- y: y- c'yi'^. - ' - - y. ' . 1 ' "~ - f - -4 '~ if yj y ^ - " ' . y f • / ( ' - '-A A - - - '^^ - - • -•. ^ • A vl A. ^ • ^ y , I- •> -A- • • • \'- - f A 1 , y. yi-" 1 i.^.iy}f.rf^..__ fiy'< - , -y y • V - - ^ ' - ^ . - A. , - X f • < ^ ^ ^ . 1 . f . -\ -f A '' V V . ^: • • • • .' V 1 • \ ' -f • . ' . . -y^ .V - • • ' r X \ ' . ' • y '...' ' '•' _^ ; • _ ~ "A^ \ ' •V ^ - y... - . 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'yf.'y'-:AA'-^ify'fA.-- -AA- 'f.''-'y'i'''-A*:fyA'i'Ay''.: f f -HA'-IAI'-- A ^i$^iy?iyAy''Ayfi'iifl':'-AiA--- .,.AA-. 'yy y^ AA ':•'-1:1'AA.•"- '-y "^^--y "A'^'yAi"-^ -4^?^. /^^ ORSS DR/YS Ov£RCJedsS^NG' I 1 \ - (- • ^ * V >• . .• f '.- f - A. \ •. ^ , I ' APPENDIXG I I I I I I I I I I I I I I I I I I I MEETING MINUTES LOCAL AGENCY RETROFIT CONTRACT 59Y025 STRATEGY MEETING M&N FILE 3807-02 DATE OF MEETING: MINUTES PREPARED BY: LOCATION: ATTENDEES: March 18-19, 1997 Moffatt & Nichol Engineers Caltrans Room 514, Farmers Market Plaza Building, West, 1801 30*^ Street, Sacramento. See Attached List ITEM DISCUSSION ACTION ALL BRIDGES 1. Caltrans requested that additional information be provided in the Geotechnical Report for all bridges including distance from the site to the controlling fault, and references to the appropriate tables be made for size and allowable bearing capacity of spread footings. GDC will comply. 2. Caltrans requested that liquefaction potential in the Geotechnical Report be noted as estimated and a reference be made to the report text for ail bridges which do not have adequate information in the LOTB to make a definitive judgment, and that a note be added where applicable stating that groundwater levels higher than assumed could increase the liquefaction potential above the estimated level. GDC will comply. 3. Caltrans noted that the sliding coefficients for all the bridges seemed high. GDC will investigate and respond. 4. Caltrans noted that soil allowable bearing capacities and passive resistance seemed high. GDC will investigate and respond. 5. Caltrans requested that for all bridges the notation of "shallow" foundations in the geotechnical report tables be changed to "spread footings," that "deep" foundations be changed to "pile," and that footing weight and overburden be utilized in considering uplift for spread footings. GDC will comply ITEM DISCUSSION ACTION 6. Caltrans requested that the stiffness values for spread footings and pile caps for all bridges be based on strain values which would tend to mobilize the soil during a seismic event. GDC will comply. 7. It was noted that scour is a potential problem at several sites in this contract. Caltrans to investigate criteria for this project. 8. Caltrans requested that sliding coefficients not be supplied for footings on pile foundations for all applicable bridges since it is not known whether or not the soil is still in contact with the pile cap. GDC will comply. CENTRAL AVE. GRADE SEPARATION (BR. NO. 56C-0373) LOCAL AGENCY: CITY OF RIVERSIDE Strategized with modifications as noted. 1. Moffatt & Nichol Engineers (M&N) summarized the proposed strategy for the structure. 2. Caltrans suggested adding transverse restraint to the bridge by adding a shear key feature to the proposed abutment and pier catcher blocks. Concern was also expressed over the drill and pressure grouting shown for the pier retrofit. Caltrans felt that inclined drill and bond dowels would be adequate. M&N will evaluate adding the requested shear keys and revise the drill and pressure grout detail. 3. It was noted that railroad approval will be required for this retrofit. Agency to process approvals. 4. It was requested that the LOTB sheets be added to strategy reports which do not contain them. M&N will comply. 5. M&N suggested that the LOTB for the adjacent bridge be obtained to see if additional information regarding liquefaction potential is available. Caltrans to obtain LOTB. INDIAN AVENUE OVERHEAD (BR. NO. 56C-0025) LOCAL AGENCY: CITY OF PALM SPRINGS Re-analyze. 1. M&N summarized the proposed strategy for the structure. 2. Caltrans requested that an alternative strategy be explored eliminating the abutment CIDH piles and allowing the superstructure to move relative to the abutment and piers. M&N will investigate. 3. Caltrans indicated that new borings at each abutment will be required if CIDH piles are to be installed. M&N will comply if required. 4. Caltrans requested that detailing of girder continuity plates account for possible misalignment of the girder webs to avoid potential construction problems. M&N will comply, 380AMin-l ITEM DISCUSSION ACTION JACKSON STREET OC AND OH (BR. NO. 56C0291) LOCAL AGENCY: CITY OF INDIO Strategized with modifications as noted. 1. M&N summarized the proposed strategy for the structure. 2. Caltrans requested that the longitudinal deck shear keys be detailed as steel elements. M&N will comply. 3. Caltrans requested that the pile information in the geotechnical report section 1.2 be correlated with the information given in section 3.3.3.2, that specific information be given with regard to pile cap elevations at bents and abutments, that distance from the site to the LOTB site be given M&N & GDC will comply. 4. Caltrans indicated that the assumption of 12" square piles may not be conservative and it seems that assuming Raymond step taper piles may be more appropriate, especially for uplift capacities. M&N will comply. 5. Caltrans indicated that liquefaction potential seems low at the site, but if it is determined to be medium, the impact to the structure should be explored. M&N will investigate. BRIDGE ACROSS COACHELLA STORM DRAIN (BR. NO. 56C-0292) LOCAL AGENCY: CITY OF INDIO Re-analyze. 1. M&N summarized the proposed strategy for the structure. 2. Caltrans indicated that collapse at piers 1,2, 15-17 is acceptable since the bridge would experience only a short drop to the soil. Retrofit cost to include fencing to prevent access under collapsing spans. M&N indicated that they would perform additional analyses assuming these spans drop to the soil. 3. Caltrans requested that the Geotechnical Report reference the tables which provide lateral wall capacities. GDC will comply. 4. Deflection at ground line and deflection at deck columns in table 5 of geotechnical re^rt appear to be reversed. GDC will change. WHITEWATER RIVER BR. AT JACKSON ST. (BR. NO. 56C-0084) LOCAL AGENCY: CITY OF INDIO Re-analyze. 1. M&N summarized the proposed strategy for the structure. 2. Caltrans requested that an alternate strategy be explored without CIDH piles. Caltrans indicated that column shear should be checked using MTD 20-4 criteria instead of the UCSD method. M&N will investigate. 3. Caltrans noted that the geotechnical report statement that the analysis is based on a LOTB from an adjacent GDC will change. ITEM DISCUSSION ACTION site appears to be incorrect. SAN JACINTO RIVER BRIDGE (BR. NO. 56C-0309) LOCAL AGENCY: CITY OF IJ\KE ELSINORE Strategized with modifications as noted 1. McLean & Schultz (M&S) summarized the proposed strategy for the structure. 2. Caltrans requested that CIDH piles all be the same diameter. M&S will comply at design stage. 3. It was noted that scour is a potential problem at this site as well as other sites in this contract. Caltrans to investigate criteria for this project. 4. Caltrans recommended drilling one boring at each abutment for CIDH pile installation data. GDC to propose boring plan. 5. The ultimate capacities of the foundation shall be listed in the Strategy Report in lieu ofthe allowable capacities M&S will comply. 6. CIDH piles must be shown on the Elevation of the General Plan and the weight of the lines shall be corrected in the Final Strategy Report. M&S will comply. 7. The dynamic friction listed in the Geotechnical Report is not applicable for pile foundations. Compatibility between soil strain values and displacement demand must be reached. GDC will comply. OIL JUNCTION OVERHEAD (BR. NO. 50C-0071) LOCAL AGENCY: KERN COUNTY Strategized with modifications as noted. 1. M&S summarized the proposed strategy for the structure. 2. Caltrans suggested that keeper plates be detailed on each flange of the steel columns instead of the vertical restrainers shown. M&S will comply. 3. Caltrans suggested that the pedestal retrofit at bent 91 be detailed to force the bearing bolts to fail and provide an adequate seat area for the calculated displacements. An alternate retrofit is to replace the bolt assembly with an elastomeric bearing pad. M&S will investigate. 4. Caltrans noted that if keeper plates are used to provide transverse capacity at the hinges, the details should account for possible misalignment of the girder webs. Contract should be alerted on the detail to field measure the plate elevations prior to fabrication. M&S will comply. 5. Caltrans requested that the geotechnical summary and tables be included in the strategy report. Caltrans requested that seismic assumptions e included as well in the Strategy Report. M&S will comply. 380AMin-l ITEM DISCUSSION ACTION 6. Caltrans indicated that the LOTB used at this site may not be appropriate due to its distance from the site. It was noted that a Caltrans' owned bridge is close by and may provide better information. Caltrans will attempt to obtain the adjacent bridge LOTB. 7. Caltrans requested that geotechnical report table 2 note 6 be clarified to indicate the point from which embedment depth is measured (i.e., top of footing, etc.) M&N will comply. 8. Caltrans indicated that the soil ultimate bearing capacity and the timber pile uplift capacity seemed high. It was noted that end bearing could be significant in the timber piles and that lack of a connection between pile and cap could limit the pile uplift capacity. M&N will investigate and reply. 9. Caltrans suggested that the strategy by reassessed using conservative geotechnical assumptions if a better LOTB is not available. M&N will comply. 10. The LOTB shall be included in the Final Strategy Report. M&S will comply. AIRPORT DRIVE UNDERPASS (BR. NO. 50C-0014) LOCAL AGENCY: KERN COUNTY Dropped. 1. M&S summarized the proposed strategy for the structure. 2. Caltrans suggested that the strategy report reference the geotechnical report instead of listing ultimate soil capacities. M&S will comply. 3. Caltrans noted that a "conservative" friction angle cannot be quantified without boring logs. 4. Caltrans requested that ultimate bearing capacities be listed in the strategy and geotechnical reports instead of allowable capacities. GDC and M&S will comply. BEALEVILLE ROAD UNDERPASS (BR. NO. 50C-0306) LOCAL AGENCY: KERN COUNTY Assess strategy after drilling new borings. 1. M&N summarized the proposed strategy for the structure. 2. Caltrans stated that catcher blocks should not be installed since failure of the bearings and the resulting drop of the superstructure will not cause collapse. M&N will investigate. 3. Caltrans recommended that additional borings be drilled at this site to determine liquefaction potential. GDC to propose boring plan. MT VERNON AVE. SEPARATION AND OH (BR. NO. 50C-0174) LOCAL AGENCY: KERN COUNTY Re-analyze 1. M&N summarized the proposed strategy for the structure. 2. Caltrans recommended considering an alternate strategy utilizing infill walls at piers 5 and 6 to avoid railroad M&N will investigate. ITEM DISCUSSION ACTION clearance problems and to avoid placing casings in water. 3. Caltrans noted that replacing existing restrainer units may avoid conflicts with new cap bolsters. M&N will investigate. 4. It was suggested that Caltrans try to obtain a better copy of the LOTB sheet since the copy in the geotechnical report is not readable. Caltrans will try to obtain a better copy. 5. Caltrans requested that pile capacities listed in the geotechnical report be based on analysis since good infomnation is available for this site. GDC will comply. HILL STREET BRIDGE (BR. NO. 57C-322) LOCAL AGENCY: CITY OF OCEANSIDE Re-analyze 1. M&S summarized the proposed strategy for the structure. 2. Caltrans recommended an alternate strategy be analyzed utilizing seismic isolation at the piers. M&S will investigate. 3. The current LOTB is unacceptable. Caltrans requested that borings be drilled at the site for the purpose of evaluating the effects of liquefaction on the structure since the potential is listed as medium. It was also requested that the LOTB from the adjacent bridge be obtained for additional information regarding liquefaction potential. Scour may also be a problem at this site, scour was not considered in the retrofit analysis. GDC to propose boring plan. Caltrans to provide LOTB. 4. Caltrans noted that these piles could be considered short for tension capacity analysis since no connection may exist between the piles and the pile cap, and reinforcing cages may not extend the full depth of the piles. GDC will investigate and revise the geotechnical report if necessary. 5. Caltrans recommended bolted connections in any retrofit scheme versus welded connections. M&S will comply, 6. Caltrans recommends the use of drill and bond dowels at abutment 1 in lieu of coring holes through the top of the vertical wall. M&S will comply. 7. Caltrans prefers coring holes in bent cap at piers locations rather than chipping of the concrete for proposed retrofit shear keys. M&S will comply. 8. Caltrans will provide supporting material on testing of laced connections to help in assessing the lacing capacities of the top chord of trusses. CT to provide. 9. The General Plan shall be relabeled at Abutment 1 for clarity. M&S will comply. 10. The LOTB shall be included in the Final Strategy Report. M&S will comply. 3807\Min-l ITEM DISCUSSION ACTION DOUGLAS DRIVE BRIDGE (BR. NO. 57C-010) LOCAL AGENCY: CITY OF OCEANSIDE Strategized with modifications as noted. •1. M&S summarized the proposed strategy for the structure. 2. Caltrans noted that pile shaft retrofit should be limited to as few piers asjDossible. M&S will investigate. 3. Caltrans requested that since the site liquefaction potential is listed as "high," the potential effects of liquefaction on the structure be addressed. M&S and GDC will investigate. 4. Caltrans noted that the uplift capacity of the piles could be limited if Raymond step taper piles were used, and requested that this issue be addressed in the geotechnical report. GDC will comply. 5. Additional drilling was not recommended. CARLSBAD OVERHEAD (BR. NO. 57C-134) LOCAL AGENCY: CITY OF CARLSBAD Re-analyze 1. M&N summarized the proposed strategy for the structure. 2. Caltrans requested the an alternate strategy be considered using infill walls at the bents and removing the CIDH piles from the abutments. M&N will investigate. 3. The City of Carlsbad noted that any horizontal clearance reductions may not be acceptable due to a planned bike route through this site. 4. The City of Carlsbad indicated that due to the high cost of retrofit and future traffic demands on the structure their preference would be to replace this bridge rather than retrofit. 5. Caltrans noted that penetration test blow counts in the LOTB are for a 1 -inch probe, and requested that correlation to SPT be added to the geotechnical report. GDC will comply. 6. Caltrans recommended that new borings be drilled at the site to ascertain liquefaction potential. GDC will propose drilling plan. 7. Caltrans stated that the angle of internal friction in the geotechnical report may not be conservative. GDC will investigate and respond. CALIFORNIA WASTEWAY BRIDGE (BR. NO. 58C-0094) LOCAL AGENCY: IMPERIAL COUNTY Re-analyze 1. M&N summarized the proposed strategy for the structure. 2. Caltrans requested that an alternative strategy be considered using continuity plates only and removing the CIDH piles at the abutments and the locking devices at the piers. GDC will investigate. I I I I I I I I I I I I I I I I I I I MEETING MINUTES LOCAL AGENCY RETROFIT CONTRACT 59Y025 STRATEGY MEETING M&N FILE 3807-02 DATE OF MEETING: MINUTES PREPARED BY: LOCATION: ATTENDEES: April 16, 1997 Moffatt & Nichol Engineers Caltrans Room 102 A & B Farmers Market Plaza Building, West 1801 30* Street, Sacramento, CA See Attached List ITEM DISCUSSION ACTION SANTA ANA RIVER BR. AT VAN BUREN BLVD. (BR. NO. 56C-0001L) LOCAL AGENCY: RIVERSIDE COUNTY 1. M&N summarized the proposed strategy for the structure. 2. Caltrans felt the 2"-3" displacement at the abutments appeared small and requested M&N to re-check these values. M&N will re-check. 3. Re-check the hinge also if displacements are found to be larger as mentioned in (2) above. M&N will re-check. 4. Instead of retrofitting the column footings with concrete overiays as proposed, Caltrans asked what would be the consequences of losing the toe piles on structural stability. If collapse does not occur, footing retrofit could be eliminated. M&N will review. ITEM DISCUSSION ACTION 5. Caltrans will provide scour potential of the column footings for the 1971 bridge extension to enable M&N to check the effects of scour on the retrofit strategy. Caltrans to provide scour potential to M&N. 6. Wet excavation may be required at the column footings. M&N to re-check unit costs for wet excavation. M&N will comply. 7. Remove all reference to the "Right Bridge" from the geotechnical report. Only the left bridge is being retrofitted in this project. GDC will comply. 8. Update all tables in the Strategy Report from the geotech report. Incorporate original structure data. M&N will comply. 9. Reconcile earthquake magnitudes noted in the PGR with that shown in ATC curve in the Strategy Report. GDC will reconcile. 10. Liquefaction potential is noted as medium in the PGR. If water is present in the channel for more than 4-5 months in a year, then potential could be high. Address and quantify in geotech report. Also address the stability of slopes at Abutments 1 and 13 under liquefaction conditions. GDC will address. 11. Address liquefaction in the Strategy Report also. M&N will comply. 12. Tension piles will be limited by their connections, particularly timber piles. Please check. GDC will re-check. 13. Use friction factor of 0.45 for base friction of shallow footings, not 0.7. GDC will modify. 14. Use 11"x17" LOTB sheets; use hard copies, not fax copies (general comment for all bridges). GDC/M&N will comply. 15. Boring log information is adequate. No additional drilling is considered necessary by Caltrans. Comment noted. SANTA ANA RIVER BR. AT MOUNT RUBIDOUX. (BR. NO. 56C-0071) LOCAL AGENCY: RIVERSIDE COUNTY 1. M&N summarized the proposed strategy for the structure. 2. Caltrans comments on Strategy Report: a. Figure 3 - Stop concrete to bottom of access opening if possible. b. Figure 4 - Pour concrete from top for Abutment 12. This will require stage construction. Angle dowels close to girders in plan view. c. Figure 5 - Use resin capsules with straight bars for bottom row of dowels in pier retrofit to protect edges of diaphragms. d. Use 11 "x17" LOTB and Pile detail sheets for clarity. M&N will address. 3. Caltrans Comments on General Plan drawing: a. Existing concrete piles are "Typ all footings". b. Move "Datum Elevation" to below line for clarity. c. Complete Typical Section to show foundations. M&N will comply. 4. Caltrans comments on Geotechnical Report: a. Review pile tension capacity in view of existing pile & dowel embedment details. Change in PGR as required. b. Piles are prestressed hollow piles. Use correct description in PGR and in report. c. Caltrans estimates liquefaction potential to be low because of low water table and better material. However, if water is present in river bed for more than about 4 months in a given year, then liquefaction potential could be higher. Upper 20 ft of river bed appears prone to liquefaction. d. Check abutments for slope stability under liquefaction and scour. GDC to comply. LOCAL AGENCY RETROFIT CONTRACT 59Y025 STRATEGY MEETING M&N FILE 3807-02 MEETING ATTENDEES NAME COMPANY PHONE# April 16,1997: Jack Ezekiel Caltrans - CCMB (916) 227-8698 Saad El-Azazy Caltrans - OEE (916) 227-8124 Steve Altman Caltrans - OSD (916) 227-8221 Darrell L. Bedderd Caltrans - CCMB (916) 227-9782 Joe Sandhu Caltrans - Hydraulics • (916)227-8037 Sam Lim Caltrans - OSC (916)227-8823 Larry Dodd Moffatt & Nichol (714) 979-2055 Al Ely Moffatt & Nichol (714) 979-2055 Jal Birdy Moffatt & Nichol (714) 979-2055 Kul Bhushan Group Delta (714) 975-7474 3807\Meetings\Min-2