Exhibit 2-13-A GERALD DESMOND BRIDGE REPLACEMENT PROJECT STRUCTURAL DESIGN CRITERIA

Transcription

1 Exhibit 2-13-A GERALD DESMOND BRIDGE REPLACEMENT PROJECT STRUCTURAL DESIGN CRITERIA Exhibit 2-13-A - Design Criteria Page i

2 TABLE OF CONTENTS TABLE OF CONTENTS... ii REVISION RECORD... iii 1. GENERAL PROVISIONS OBJECTIVES & SCOPE LIMITS OF APPLICABILITY GOVERNING SPECIFICATIONS UNITS DESIGN APPROACH BRIDGE LAYOUT DESIGN SERVICE LIFE DESIGN LOADING STRUCTURAL DEAD LOADS SUPERIMPOSED DEAD LOADS LIVE LOADS Design Truck, Design Tandem and Design Lane Loads Permit Vehicle Loads Dynamic Load Allowance Pedestrian Loads Deflection and Vibrations Limitations Live Load Contribution under Seismic Conditions FATIGUE LOADING WIND LOADS Serviceability Wind Event Aerodynamic Stability Wind Event SEISMIC LOADS THERMAL LOADS DIFFERENTIAL SUPPORT MOVEMENT LIMIT STATES COMBINATIONS CONCRETE DESIGN MATERIALS Concrete Mild Steel Reinforcement Prestressing Steel DESIGN Stress Limits in Prestressed Concrete Members Concrete Cast-in-Place Superstructure and Substructure Corrosion Protection Stirrups Design in Segmental Box Girders STEEL DESIGN MATERIALS Structural Steel Miscellaneous Steel Stay Cables DESIGN Stay Cables Miscellaneous SEISMIC DESIGN Exhibit 2-13-A - Design Criteria Page ii

3 5.1 GENERAL PERFORMANCE REQUIREMENTS Safety Evaluation Structural Components Safety Evaluation Geotechnical Considerations Functional Evaluation Performance Assessment Seismic Loading during Construction DEFINITION OF GROUND MOTIONS ANALYSES FOR DETERMINATION OF DEMANDS Service Load Demands and Combination with Seismic Demands Seismic Demands Nonlinear Local Analysis for Evaluating Seismic Demands ANALYSES FOR DETERMINATION OF CAPACITIES Structural Steel Component Capacities Tower Shafts and Strain Limits Tower Connections Reinforced Concrete Component Capacities Allowable Concrete Strain Values Allowable Reinforcement Strain Values Main Span Bridge Tower and End Bent Shaft Energy Dissipating Shear Link (If Energy Dissipating Shear Link Are Used) Energy Dissipating Shear Link Testing (If Energy Dissipating Shear Links Are Used) Concrete Pile Caps Allowable CISS Pile Shell Strain Values Shear Design of Ductile Concrete Members Plastic Hinge Length Exhibit 2-13-A - Design Criteria Page iii

4 1. GENERAL PROVISIONS 1.1 Objectives & Scope The purpose of these criteria is to document the specifications used for the final analysis and design of the Project. The Design-Builder shall meet the requirements of these criteria in the completion of the Project. 1.2 Limits of Applicability These criteria apply to elements of the Main Span Bridge and Approach Bridges between SR 47and SR Governing Specifications Standards are listed in the beginning of the structures section. 1.4 Units 1. The bridges shall be designed using English Units. 2. The units shown in the final plans shall be English Units. 1.5 Design Approach The Load Resistance Factor Design (LRFD) method as defined in AASHTO LRFD Bridge Design Specifications, 4 th Edition, and as modified by the Caltrans California Amendments to the AASHTO LRFD Bridge Design Specifications shall be used for the design of all structural members. Exceptions and additions to the AASHTO LRFD Bridge Design Specifications, 4 th Edition, are defined in these project-specific Design Criteria. Design for seismic loads shall be in accordance with Caltrans Seismic Design Criteria, Caltrans Guide Specifications for Seismic Design of Steel Bridges, AASHTO Guide Specifications for LRFD Seismic Bridge Design, NCHRP 12-49, ATC-32, and the specific requirements of these project-specific Design Criteria. The design requirements may differ for the Main Span Bridge and Approach Bridges as defined by these criteria. 1.6 Bridge Layout Bridge layouts shall use the vertical and horizontal datums identified elsewhere in the Contract Documents. 1.7 Design Service Life The structure design service life is 100 years. Exhibit 2-13-A - Design Criteria Page 1

5 2. DESIGN LOADING 2.1 Structural Dead Loads Structural dead loads shall be based on unit weights of materials and the computed volumes of the structural elements. The following unit weights shall be used unless the Design-Builder demonstrates different loadings are appropriate: Concrete, Reinforced or Prestressed (Including Reinforcing) Normal Weight Concrete, f c 5000 psi Normal Weight Concrete, f c > 5000 psi Lightweight Concrete 150 pcf 160 pcf 120 pcf Steel Fabricated Plate Steel Rolled Shapes Cable Stays 490 pcf 490 pcf 490 pcf 2.2 Superimposed Dead Loads Superimposed dead loads shall be as follows unless the Design-Builder demonstrates different loadings are appropriate: Steel Railings Concrete Barriers Initial Polyester Concrete Overlay Main Span Bridge Approach Bridges 490 pcf 150 pcf 150 pcf 150 pcf Future Wearing Surface Maintenance facilities and Utilities 6.25 psf Actual Weight Provision for future Utilities shall be considered as follows: Future Utilities 5 psf placed in a 10 ft wide strip and located longitudinally along a bridge and transversely between the outside edges of a deck to create the worst case loading condition. Loading for future Utilities is in addition to the calculated weight for specific Utilities accounted for in the design of the bridges, and includes allowance for Utilities, Utility supports, service platforms, service platform supports and associated miscellaneous metal. 2.3 Live Loads Live loads on the Main Span Bridge and the Approach Bridges shall be as defined by AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section for traffic lane width of 12 feet. Multiple presence factors shall be used in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Pedestrian loads shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Exhibit 2-13-A - Design Criteria Page 2

6 2.3.1 Design Truck, Design Tandem and Design Lane Loads The single-lane average daily truck traffic (ADTT SL ) shall be taken as 7,000 (year 2056). Average daily traffic (ADT) shall be taken as 123,000 (year 2056). Vehicular live load shall be AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, HL-93 with an increase of 10% for AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Strength I and Service I, II, and III limit states in designing following structural members: All members in the Main Span Bridge superstructure including stay cables, edge girders, floor beams, stringers, bearings, and deck. All members in the Approach Bridges, including foundations. Main Span Bridge seismic energy dissipation elements, tension elements between stay cable anchorages and diaphragms, if the seismic energy dissipation elements and tension elements are used. Vehicular live load shall be AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, HL-93 for Main Span Bridge towers and end bents, including foundations. A maintenance vehicle load as designated by one H10 truck shall be placed between the two median barriers on the Main Span Bridge for Strength I Load Combination Permit Vehicle Loads Permit loads (P-15) shall be considered for design of the bridge superstructure as defined in AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments. When considering Permit loads (P-15), the bridge shall satisfy AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Load Combination STRENGTH II Dynamic Load Allowance Dynamic load allowance shall be applied in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section and PTI Recommendations for Stay Cable Design, Testing and Installation for dynamic load allowance from cable stay loss (Article 5.5). Exhibit 2-13-A - Design Criteria Page 3

7 2.3.4 Pedestrian Loads Pedestrian loads shall be applied to the non-motorized Class I bikeway (bike path) and pedestrian sidewalk in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Deflection and Vibrations Limitations Bridges with a non-motorized Class I bikeway (bike path) and/or pedestrian sidewalk shall be designed to avoid pedestrian discomfort from affects of vehicular traffic, synchronized pedestrian loading, and wind. When subject to the required vehicular loading and simultaneous occurring winds up to 30mph, the maximum vertical and horizontal acceleration of the superstructure shall be limited to 5%g and 2.5%g respectively at an operation speed of 25 mph. When loading two tracks or lanes, the vehicles shall be assumed to be traveling in opposing directions and placed on the bridge so as to produce the maximum deck accelerations. The procedure published by the Technical Department for Transport, Roads and Bridges Engineering and Road Safety (Sétra) of the French Ministry of Transport and Infrastructure, entitled Technical Guide, Footbridges, Assessment of vibrational behavior of footbridges under pedestrian loading, shall be used for evaluating the magnitude of the excitation and limiting frequencies. When evaluating synchronous lateral excitation (SLE), the following parameters shall be considered: Accelerations shall be limited to Range 1 for Maximum Comfort (0.00 to 1.64 ft/s2 Vertical, 0.00 to ft/s2 Horizontal) Pedestrian loading shall be considered for Class I, II, and III traffic. Analysis of mode shapes coupled in multiple directions shall consider simultaneous pedestrian loading in those directions Live Load Contribution under Seismic Conditions Live load shall be considered for combination with seismic demands in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, (EXTREME EVENT - I). The loading factor EQ shall be taken as 0.17 for all structures. EXTREME EVENT I shall apply to either Functional Evaluation Earthquake or Safety Evaluation Earthquake events. 2.4 Fatigue Loading For the Fatigue I limit state, the fatigue load shall be a single design truck, as specified in AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section , occupying a single lane in each traffic direction. The load factor of 2.0 shall be used for infinite fatigue life. For the Fatigue II limit state, the fatigue load shall be one Permit truck as specified in AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Wind Loads Wind analysis and design for the Approach Bridges shall be performed in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments. Wind analysis and design for the Main Span Bridge shall be performed in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section 3.8 and ANSI/SEI 7. For the Main Span Bridge, both static and dynamic wind effects shall be considered, utilizing computer models of the bridge that incorporate the results of wind tunnel tests of section models of the deck. Wind tunnel tests shall include smooth and turbulent flow, and 0.5% to 1.5% damping. Wind analysis and design shall include both a high-probability Serviceability Event and a lower-probability Aerodynamic Stability Event. Exhibit 2-13-A - Design Criteria Page 4

8 2.5.1 Serviceability Wind Event The Serviceability wind event shall have a probability consistent with a mean return period of 100 years, but not less than a basic wind speed of 85 mph as defined in ANSI/SEI 7. In this event, the nominal stresses and/or loads and resistance factors of AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, shall be met by all components in the completed bridge Aerodynamic Stability Wind Event Vertical deck accelerations shall not exceed 0.03g for winds up to 30 mph and 0.10g for winds above 30 mph up to 45 mph. Furthermore, the bridge shall show no sign of flutter instability up to a wind velocity of 1.4 times the one-hour mean 100-year wind. If the bridge shows any sign of aerodynamic instability within these limiting wind velocities, the cross section and other bridge design features shall be revised until the requirements are met. Bridge responses to wind during construction (free standing tower, partially erected bridge, etc.) shall be evaluated from wind tunnel tests for 20-year wind. The Design-Builder shall identify temporary remedial measures to counteract any distress. 2.6 Seismic Loads Seismic design issues are covered in Section 5 of this document. 2.7 Thermal Loads Design temperature range shall correspond to requirements for a moderate climate. A temperature gradient between the top and bottom of the superstructure shall be considered in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Differential Support Movement Differential support shall be considered as follows: 1. Support movements during construction, as the loads from the structure applied to the foundations shall be considered in design. 2. Support movements during the service life of the bridge, due to the time dependent strains in the subsurface materials, shall be considered in design. 3. Permanent deformation of the structure due to earthquake shall be acceptable within the strain limits defined in Section 5 of this Design Criteria. 2.9 Limit States Combinations Load factors and load combinations shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Tables and , except as follows: The effects of stay cable force adjustments are treated as dead load. Service load thermal loading combination for the cable-stayed spans shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Secondary effects due to post-tensioning (EL) shall have a load factor, P of 1.0. The load modifier for "importance" should be taken as 1.0 for "Typical Bridges". Exhibit 2-13-A - Design Criteria Page 5

9 3. CONCRETE DESIGN 3.1 Materials Concrete Superstructure deck, precast deck panels and edge girders, f'c = 4000 psi minimum, 8000 psi maximum, where f c = 28-day compressive strength. Concrete strengths greater than 8000 psi require Port Approval. Towers and bent columns and bent caps, f'c = 4000 psi minimum, 8000 psi maximum. Footings and pile caps, f c = 4000 psi minimum, 5000 psi maximum. Cast In Steel Shell (CISS) piles, Cast In Drilled Hole (CIDH) piles, f c = 5000 psi minimum. Barriers and retaining walls: f'c = 3600 psi minimum. Prestressed Concrete: f'c = 8000 psi maximum, 4000 psi minimum. Prestressed concrete shall meet the requirements of AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments and be limited to the following allowable stresses: Temporary stresses during construction and before losses: f'ci = 3500 psi minimum at time of prestressing operations fci = 0.60 f'ci compression for pretensioned and post-tensioned members Tensile stress limits shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Table Stresses at service load after losses: Compressive stress limits shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments Table Tensile stress limits shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments Table Transversely Prestressed Bridge Deck Design - Tensile stress limits shall be A. Top of deck- No tension B. Bottom of deck- ' 3 f c psi Member section force effects that include seismic loading shall use the expected concrete compressive strength as defined in Section of this Design Criteria. Modulus of Elasticity E c for concrete elements shall be determined in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section , unless more precise data is available. When performing analysis that includes seismic loading, the modulus of elasticity shall be based on the expected concrete strength as defined in Section of this Design Criteria. See also section of this Design Criteria for concrete material properties for ductile reinforced concrete plastic hinge elements Mild Steel Reinforcement All mild steel reinforcement shall be ASTM A706 (Grade 60). The following properties shall be used in the design: Specified minimum yield stress: Specified maximum yield stress: Fy = 60 ksi Fy max = 78 ksi Exhibit 2-13-A - Design Criteria Page 6

10 Specified maximum tensile stress: Modulus of elasticity: Fu max = 107 ksi Es = 29,000 ksi Prestressing Steel Strand Prestressing Steel shall meet the following requirements: 0.6" or ½" diameter ASTM A416 low relaxation strand f's = 270,000 psi ultimate strength Stress limits shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Table Es = 28,500,000 psi modulus of elasticity All prestressing steel shall be bonded. Bar Prestressing Steel ASTM A722 (Type II) shall meet the following requirements: High strength threaded bars f's =150,000 psi ultimate strength Stress limits shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Table Es = 30,000,000 psi modulus of elasticity Prestressing Losses shall meet the following requirements: Friction losses based on AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Anchor set for strand = ⅜" Anchor set for bar = ⅛" Elastic Shortening losses based on AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Long-term losses - It is the responsibility of the Design-Builder to select an appropriate creep and shrinkage code model, which is subject to review and Approval by the Port. 3.2 Design Stress Limits in Prestressed Concrete Members Stress limits for concrete in prestressed and post-tensioned concrete members shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section Stress limitations for prestressing tendons shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Table Principle tensile stress for web shear in girders during service conditions shall not exceed the following limits: Normal weight concrete: Lightweight concrete: * f c (ksi) * f c (ksi) Where: f c = 28-day compressive strength in ksi. Exhibit 2-13-A - Design Criteria Page 7

11 3.2.2 Concrete Cast-in-Place Superstructure and Substructure Design of cast-in-place concrete shall conform to AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, and these Design Criteria. For shear design of concrete members that may experience plastic hinging, see Section of this Design Criteria Corrosion Protection Steel Casing Thickness Reduction for CISS Piles: in/face/year plus 1/16 in. Thickness reduced at outer face of the CISS piles only. Concrete Cover for Reinforcement: Concrete Cover: Minimum cover per AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Table for marine environment. Concrete cover for the top mat of deck reinforcement in the Main Span bridge and Approach Bridges shall be 2.5 inches measured from the bottom of the polyester concrete wearing surface or top of structural deck. Of the 2.5 inches, the top 0.5 inches is sacrificial and shall not be relied upon for structural capacity. Concrete Cover within CISS Casings: Minimum cover shall be 2 in. Concrete Cover within CIDH Concrete Piles: Minimum cover shall be 6 in. Cathodic Protection: Not allowed Stirrups Design in Segmental Box Girders Stirrups in girder webs shall be designed for the longitudinal shear and torsion (A v ) and the out of plane bending from the transverse box girder analysis (A f ). The minimum area of steel should not be less than the larger of the following combinations of the two effects: a) A v + 0.5A f or b) 0.5A v + A f or c) 0.7(A v + A f ) (Construction and Design of Prestressed Concrete Segmental Bridges, Podolny & Muller, page 203) Exhibit 2-13-A - Design Criteria Page 8

12 4. STEEL DESIGN 4.1 Materials Structural Steel ASTM A709, Grade 36, HPS50W, or HPS70W as applicable. The equivalent specification, ASTM A36, shall be used with the ANSI/AWS Bridge Welding Code. ASTM A36-08/ASTM A790 Grade (for Energy Dissipating Shear Links only if Energy Dissipating Shear Links are used) Yield Strength, minimum = 38 ksi Yield Strength, maximum = 42 ksi All steel shall be painted. Interior of closed steel box sections shall be painted with two coats of primer. Orthotropic Deck: The orthotropic deck design details shall be in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, (Sections 2, , 6 and 9) except that the loading shall be 3xHS 15. Deck plate thickness shall be a minimum of 5/8 inch Rib plate thickness shall be not less than 5/16 inch The weld between the deck plate and ribs shall be 80% penetration into the rib wall thickness and shall be made using SAW process. The weld between the ribs and floor beam web at the cutout shall be a full penetration groove weld, with runoff tab, for a minimum of 4 inch from the cutout. The run-off tab shall be ground flush to a radius. An internal rib bulkhead plate is to be provided at floorbeam locations. Overlay shall be a two-layer system with liquid water proofing membrane overlaid by a total thickness of 1½ inch asphalt comprised of ½ inch high density asphalt and 1 inch latex modified asphalt. Live Load Deflection limitations: Deflection of deck plate = span length/300 Deflection of ribs = span length/1000 Relative live load deflection between adjacent ribs = 0.1 inch Miscellaneous Steel Steel Casing for CISS piles ASTM A252, Grade 3 High Strength Bolts ASTM A325, A490 Anchor bolts ASTM A307, F1554, A354 or A449 as deter- mined by design. ASTM A722 thread- bars may also be used for anchor bolts in specific applications Stay Cables See Exhibit 2-13-D. Exhibit 2-13-A - Design Criteria Page 9

13 4.2 Design Stay Cables Stay cables shall be designed in accordance with PTI Recommendations for Stay Cable Design, Testing and Installation. The LRFD Group combinations as specified in AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section for the Strength, Service, Extreme Event, and Fatigue limit states, and these Design Criteria, shall be used to supplement the PTI Recommendations for Stay Cable Design, Testing and Installation. A minimum tension force of 10% of the dead load a stay cable experiences shall be provided in the staycables during all extreme events. Provision shall be made for the replacement of any individual cable as required by the PTI Recommendations for Stay Cable Design, Testing and Installation. Details shall be provided for the replacement of any individual stay cable by detensioning at the live end anchors. After final adjustment, the polyethylene pipe sheathing shall not be filled with grout. Provision shall be made for the adjustment of any individual cable during and after completion of construction Miscellaneous Expansion joints and bearings shall be designed to provide the movement range required to allow free movement under the temperature changes given in Section 2.7 of this document, as well as for seismic movements under the Functional Evaluation Earthquake (Section 5.1). Expansion joints and bearings shall also be designed to prevent collapse of the joint or bearing when subjected to the maximum anticipated movement under the Safety Evaluation Earthquake (see Section 5.1) Maintenance facilities or accesses, including hatches, stairways, walkways, platforms and ladders shall be designed in accordance with CALOSHA standards. Exhibit 2-13-A - Design Criteria Page 10

14 5. SEISMIC DESIGN Seismic design of the Project shall be performed in accordance with Caltrans Seismic Design Criteria and Caltrans Guide Specifications for Seismic Design of Steel Bridges, augmented with pertinent provisions of ATC- 32, NCHRP 12-49, AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, AASHTO Guide Specifications for Seismic Isolation Design, PTI Recommendations for Cable Stay Design, Testing, and Installation, and Project specific criteria as detailed in this document. 5.1 General Performance Requirements Seismic design of the Project shall consider both the Safety Evaluation Earthquake (SEE) and the lower level Functional Evaluation Earthquake (FEE). Seismic performance levels, expressed in terms of damage levels, are defined as follows: No Damage : Defined for structural members as the nominal capacity as described in AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments. Nominal, not expected material properties shall be used and increased member strength due to the effects of confinement steel shall be ignored. No damage is defined as full serviceability without repair or replacement. Minimal damage : Although minor inelastic response may occur, post-earthquake damage is limited to narrow cracking in concrete, and inconsequential yielding of secondary steel members. Damage to nonstructural components of the cable system would be allowed. Moderate damage : Inelastic response may occur, resulting in concrete cracking, reinforcement yield, minor spalling of cover concrete and minor yielding of structural steel. The extent of damage shall be sufficiently limited such that the structure can be restored essentially to its pre-earthquake condition without replacement of reinforcement or replacement of structural members. Significant damage : Damage consisting of concrete cracking, reinforcement yielding, major spalling of concrete and deformations in minor bridge components which may require closure of the bridge to repair. Partial or complete replacement of secondary elements may be required in some cases. Secondary elements are those that are not a part of the gravity load resisting system. Meeting the stress and strain limits specified in these criteria form the basis for satisfying the seismic performance level goals of the Project Safety Evaluation Structural Components The SEE for structural evaluation corresponds to a mean return period of 1,000 years, representing approximately a 10% probability of occurrence in 100 years. In this earthquake, the bridge can be subject to primarily minimal damage with some moderate damage and some significant damage in secondary components as described in this section. The Design-Builder shall design the bridge components to the following behavior levels under the SEE: Piles/Drilled Shafts: Minimal damage. Pile Caps: Minimal damage Approach Bridge columns and abutments (above pile caps): Moderate damage. Main Span Bridge Towers and End Bents (above pile caps): Minimal damage. Energy Dissipating Shear Links, if used (at Main Span Bridge Towers and End Bents): Significant damage. Approach Bridge abutment backwalls: Significant damage. Superstructure: Minimal damage. Exhibit 2-13-A - Design Criteria Page 11

15 Bearings, Hinge Beams and Shear Keys: Moderate damage. Expansion Joints: Significant damage, without collapse of the joint Cable Systems (structural elements): No damage. Cable Systems (non-structural elements): Minimal damage. Permanent offsets at Main Span Bridge towers and end bents at the deck level relative to pile caps must be avoided, except at the SEE level permanent offsets not exceeding 6 in any direction are permitted. Such offsets are exclusive of affects from adjoining Approach Bridges. Seismic affects from supported Approach Bridge spans shall be considered and shall not contribute to the end bents exceeding the 6" residual displacement. Approach Bridge span residual displacements at the end bents need not comply with the 6" residual displacement limit. Permanent offsets of the foundations are also permissible if the strain limits specified in Section 5.4 of this document are not exceeded and the permanent offsets do not prevent use of the bridge subsequent to the SEE event after repairs are completed Safety Evaluation Geotechnical Considerations Soil Liquefaction: The SEE event shall be used to assess liquefaction potential and corresponding downdrag forces, if applicable. If liquefiable soils are determined to be present, and it has been determined that they may in fact liquefy under the design earthquake for the site, the structure shall be designed to withstand the forces and moments resulting from the lateral and vertical movements caused by the liquefaction. Soil stabilization may be used to mitigate liquefaction conditions. Additionally, the design of the foundations shall be evaluated with the soil in a liquefied state. Slope Stability: For the SEE event, deformations of the supporting ground mass and displacements of the slopes shall be considered in the design of the bridge components. If necessary, the soil shall be stabilized to protect the bridge from damage due to lateral spreading, soil deformation and associated applied forces Functional Evaluation The FEE is defined as an earthquake that has a return period of 100 years, representing approximately a 60% probability of occurrence in 100 years. In this earthquake, Approach Bridges can be subject to damage only if it can be classified as minimal. The Main Span Bridge, including Main Span Bridge tower, end bents, supporting piles, superstructure, and stay cable system shall meet the requirements of the No Damage performance level. Main Span Bridge and Approach Bridge bearings shall meet the requirements of the No Damage performance level. The expansion joint between the Main Span Bridge and Approaches Bridges shall meet the requirements of the Minimal Damage performance level. For reinforced concrete elements, minimal damage for the FEE event shall be based on the member strengths determined using the strain limitations given in Section Performance Assessment The seismic performance of all structures shall be assessed by verifying estimated structural demands on components are less than or equal to estimated structural capacities of those components. Methods for determining demands and capacities are defined in the following sections. When significant yielding of components is allowed, demand and capacity are defined by strain or rotational limits. When components are required to remain elastic or experience minor yielding, demand and capacity are defined by force Demand/Capacity (D/C) ratios. All capacity-protected components, as defined by Caltrans Seismic Design Criteria or these criteria, shall have a force D/C ratio of 1.0 or less when subjected to over-strength forces. When checking seismic conditions, use the corrosion allowance for pile casings at 50 percent of the 100-year design life. The horizontal diaphragms and tension elements that transfer for from one stay to the next between shafts or elements that make up a tower or end bent column, if used, shall be capacity protected. Exhibit 2-13-A - Design Criteria Page 12

16 5.1.5 Seismic Loading during Construction For all bridges, the seismic loading during all phases of construction shall be designed to resist forces as described in Caltrans Bridge Memo to Designers Definition of Ground Motions Ground motions for use in dynamic seismic analysis of the bridge structures shall be taken from the Project Seismic Ground Motion Report information provided in Book 2, Section 8, Exhibit 2-8-F which documents the project-specific ARS design curves and spectrum-compatible ground motion time histories for the SEE and FEE. The Project consists of three soil zones: West Approach, Main Span, and East Approach. For each soil zone, ARS design curves and earthquake time histories that were spectrally matched to the ARS design curves were developed using the Probabilistic Seismic Hazard Analyses (PSHA) and considering the site response characteristics of the subsoils. Revision to the project-specific ARS design curves and earthquake time histories provided in in Book 2, Section 8, Exhibit 2-8-F will not be allowed. Non-linear time history and response spectrum analyses shall be used in the evaluation of the bridges, as described in Section For the purpose of non-linear time history analyses, the ground motions shall consist of three, 3-component time histories consistent with the SEE and one, 3-component time history consistent with the FEE. Each time history shall consist of 2-horizontal orthogonal components and one vertical component. For the SEE, the envelope of the three time-history ground motion analyses results shall be used to design the bridge. The Project Site is located in the seismically active southern California area. The principal faults affecting the seismic hazard of the bridge are the Newport-Inglewood (Cherry Hill Segment) Fault northeast of the bridge and the Palos Verdes Fault southwest of the bridge. Since the location of the bridge places it in close proximity to the two active faults, near-fault directivity effects, including velocity pulses, shall be included in the time history analyses. 5.3 Analyses for Determination of Demands Demands on structural components of a bridge shall be determined by analysis of global three dimensional computer models of the bridge that represent its dominant linear and nonlinear behavior and the effects of soilfoundation-structure interaction. Demands shall be evaluated as load-type quantities (forces and moments) or as displacement-type quantities (displacements, relative displacements, and rotations) as required by the evaluation rules for various components Service Load Demands and Combination with Seismic Demands For combination with seismic demands, component demands due to dead load, traffic load, temperature changes, and wind shall be determined by static analyses of global models Seismic Demands Seismic demands shall be determined by nonlinear dynamic time history analysis for the Main Span Bridge and at least one Approach Bridge frame, but not less than 700 feet of Approach Bridge, adjacent to each end of the Main Span Bridge. The analysis shall be completed for uniform support excitations for all pier locations within the same soil zone developed for the project. Appropriate analysis methods as specified in Caltrans Seismic Design Criteria shall be used for all other Approach Bridge structures. Non-linear dynamic time-history analysis shall incorporate the following: Both dead load and seismic load analyses shall be geometrically non-linear to account for the geometric stiffness of the cable elements. Boundary condition non-linearities shall be accounted for in the form of gap elements at expansion joints and foundation impedances. The structural model shall explicitly consider the geometric nonlinearity, inelastic structural components Exhibit 2-13-A - Design Criteria Page 13

17 and other inelastic elements (e.g. dampers). Any reinforced concrete members with a force Demand/Capacity (D/C) ratio larger than 0.5 shall be modeled with adjusted material and section properties to represent the cracked section. Structural steel members with a force D/C ratio less than 1.5 shall be modeled with elastic elements. Any members with a force D/C ratio larger than 1.5 shall be modeled with nonlinear elements. Rayleigh damping is to be used for non-linear dynamic time-history analysis. Modal damping may be used for other analytical tools. The range of Rayleigh damping values represents the target maximum and minimum damping values that apply over the dominant periods of the various element groups. The maximum upper range of Rayleigh damping for non-linear dynamic time-history analysis shall not exceed the following: Reinforced Concrete Columns: 4% - 6% Reinforced Concrete Towers: 4% - 6% Steel Towers: 2% - 5% Steel Superstructure: 2% - 5% Concrete Superstructure: 3% - 5% Foundations: 8% Rayleigh damping shall be incorporated into the model with values for each element group representing the expected extent of inelastic energy dissipation in that group. The range of dominant periods for the various bridge components used to select Rayleigh damping shall capture at least 90% of the mass of the bridge components under consideration. If higher Rayleigh damping is used at a foundation, the higher damping shall be limited to piling and pile caps that are entirely below grade and shall be established from bridge foundation only component models. Anchor points used for establishing Rayleigh damping at foundations shall be selected for the range of dominate periods of the foundation elements that capture at a minimum 90% of the mass of the foundation elements. When the pile cap dominates the foundations response, it is acceptable to exclude the mass of piles from the bridge foundation only component model. When soil springs or other foundation elements are represented by hysteretic elements in global models, total foundation damping shall not exceed an equivalent viscous damping of 8% with respect to the foundation stiffness and mass in defining the Rayleigh damping parameters. Modal Damping for Other Analytical Tools: Reinforced Concrete Columns: 5% Reinforced Concrete Towers: 5% Steel Towers: 3% Steel Superstructure: 3% Concrete Superstructure: 5% Main Span Bridge tower shafts and end bent column shaft seismic energy dissipation elements, if used, shall be explicitly modeled to represent the energy dissipation characteristics of each seismic energy dissipation element. The global seismic analysis model for the Main Span Bridge shall use explicit foundation modeling for the Main Span Bridge and at least one Approach Bridge frame, but not less than 700 feet of Approach Bridge, adjacent to each end of the Main Span Bridge. Explicit foundation modeling in the global model shall use the same spectrum-compatible motions applied uniformly at all depth at the ground nodes along the full length of the pile. The explicit foundation modeling shall include a representation of each individual pile, with distributed soil supports over the entire length of the pile. The uniform ground motions documented in Book 2, Section 8, Exhibit 2-8-F shall be used to excite the soil-pile structure system. For all other structures, foundation substructure models may be used to capture significant soil-pile interaction effects. The foundation substructure should consist of a linear stiffness and mass matrices representing the entire soil-pile system. The linearized foundation stiffness and mass matrices must be approximated with the anticipated strain levels during the design earthquake. The project ground motions developed in each soil zone shall be used to excite the foundation substructure. The same input earthquake ground motions shall be used for all supports within the same soil zone. Exhibit 2-13-A - Design Criteria Page 14

18 When modeling of foundations for seismic demand evaluations, softening effects of local soils shall be considered including seismic induced large deformations and liquefaction. The ground motions documented in Book 2, Section 8, Exhibit 2-8-F shall be used for all cases of foundation modeling, with and without softening effects. When checking AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Extreme Event I, a permanent load factor, p, of 1.0 shall be used for Load Type DC. Damping curves shall be submitted with the seismic analysis and design Nonlinear Local Analysis for Evaluating Seismic Demands At a minimum, nonlinear local analyses shall be performed on the following bridge elements or conditions to supplement the global three dimensional nonlinear multi-support dynamic time- history analysis: Regions of significant Stress Concentrations (such as seismic energy dissipation elements, tower diaphragms, tower tension ties, mid-span pipe hinges, etc) Locations of discontinuous load path Fracture critical elements Energy dissipating regions and devices These analyses shall provide independent assessment of controlling seismic demands based on the assumption of maximum plastic moments and forces developed by potential plastic hinges or other inelastic behavior. These analyses shall be used to confirm adequate structural performance in the event that the SEE demands obtained from the global time-history analysis are exceeded. 5.4 Analyses for Determination of Capacities Capacities of structural components of a bridge shall be determined by analysis of local elastic and inelastic computer models of the components. Capacities shall be evaluated as load-type quantities (forces and moments) or as displacement-type quantities (displacements, relative displacements, rotations, and curvatures) as required by the evaluation rules for various components Structural Steel Component Capacities Cable Stays: The load capacity of cable stays shall in accordance with PTI Recommendations for Cable Stay Design, Testing, and Installation Tower Shafts and Strain Limits The towers shall be designed in accordance with ATC-32 Improved Seismic Design Criteria for California Bridges: Provisional Recommendations augmented by the following requirements: l/ l req > 2.0 b/t 2l P max /Area 0.6F y Where: l = the relative stiffness of the longitudinal stiffener to the tower skin wall b/t = the width to thickness ratio of the skin wall P max /Area = the maximum axial stress Exhibit 2-13-A - Design Criteria Page 15

19 Main Span Bridge steel tower allowable strain limit value at the SEE Event shall meet the following requirements: Tower without seismic energy dissipation elements: 4* y where y is the yield strain of the steel Tower with seismic energy dissipation elements: The tower shall be designed to remain essentially elastic. Main Span Bridge steel tower allowable strain limit value at the FEE Event shall not exceed y Tower Connections Tower splices shall be designed for the expected yield strength capacity of the component in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments. Tower anchorage to the foundation shall be designed based on global push-over of the tower. The capacity of the tower anchorage shall be larger than the over strength demands associated with plastic hinging of the tower shaft. The capacity shall be evaluated in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments Reinforced Concrete Component Capacities The expected nominal moment capacity M ne of ductile reinforced concrete members and capacity protected members as defined in Caltrans Seismic Design Criteria Section 3.4 shall be based on expected material strengths: f ce = 1.3 * f'c (expected concrete compressive strength) f ye =68 ksi (ASTM A706, Grade 60) (expected reinforcement yield) Maximum concrete strains at the nominal moment capacity M ne shall not exceed 0.003, and the reinforcing steel strains shall be limited to the allowable reinforcement strain values defined in Section of this document. Capacity protected members shall be designed for forces derived from design overstrength moments (M o ) of the members framing into the capacity protected member. The design overstrength moment M o shall be based on expected material strengths. Plastic moments shall be determined from moment-curvature analysis that considers the effects of concrete confinement and strain hardening of the reinforcement. The overstrength moment shall be taken as 1.20 times the calculated plastic moment at the design deformation of the element. The horizontal diaphragms between shafts or elements that make up a tower or end bent column, if used, shall be capacity protected. Exhibit 2-13-A - Design Criteria Page 16

20 5.4.5 Allowable Concrete Strain Values The allowable concrete strain values for each earthquake level and components shall be according to the table below. The stress-strain relationships developed by Mander for confined concrete shall be used to calculate the values as a percentage of cu. When the no damage performance level is required, concrete strain limit of pursuant to AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section shall be taken at the extreme face of the concrete component and not the confined core. ALLOWABLE CONCRETE STRAIN VALUES Location Main Span Bridge Towers Main Span Bridge End Bents Main Span Bridge CISS/CIDH Piles Approach Bridge Columns Approach Bridge CISS/CIDH Piles All other Elements Minimal Minimal Minimal Minimal cu definition shall be per Caltrans Seismic Design Criteria Allowable Reinforcement Strain Values SEE Strain cu cu cu cu cu cu No No No Minimal Minimal Minimal FEE Strain To achieve the performance goals for the SEE and FEE event, the strains in reinforced concrete members, shall be limited to the values in the table below. The design level of peak steel strain values given in this table are to be used for evaluating the moment-curvature relationship for all potential plastic hinge areas. Damage Damage Moderate Moderate ALLOWABLE REINFORCEMENT STRAIN VALUES SEE FEE Location Damage Damage Strain Strain Main Span Bridge Towers Minimal No - Main Span Bridge End Bents Minimal No Main Span Bridge Tower + End Bents Lateral Reinforcement (Bars #8 and Smaller) Minimal 0.05 No Main Span Bridge CISS/CIDH Piles Minimal No Approach Bridge Columns (Bars #11, #14 & #18) Moderate 0.05 Minimal Approach Bridge Columns (Bars #10 and Smaller) Moderate 0.06 Minimal Approach Bridge CISS/CIDH Piles Minimal 0.02 Minimal All other Elements Moderate 0.06 Minimal u, R su, sh f u, f ue, y, ye, definitions shall be per Caltrans Seismic Design Criteria. Exhibit 2-13-A - Design Criteria Page 17

21 5.4.7 Main Span Bridge Tower and End Bent Shaft Energy Dissipating Shear Link (If Energy Dissipating Shear Link Are Used) Except for base fixity resistance from the dual columns, frame lateral resistance shall only be from the interaction of the twin columns and Energy Dissipating Shear Links or Seismic Energy Fuses. All loading combinations not including seismic loads shall not exceed the nominal yield strength of the Energy Dissipating Shear Links or Seismic Energy Fuses. All components of Energy Dissipating Shear Link or Seismic Energy Fuse connections to Main Span Bridge tower shafts and end bent column shafts shall be designed as capacity-protected elements and shall be detailed to permit their removal and replacement after a seismic event. The rotation demand on Energy Dissipating Shear Links or Seismic Energy Fuses shall be limited to a maximum value of 0.01 radians at the SEE level and radians at the FEE level Energy Dissipating Shear Link Testing (If Energy Dissipating Shear Links Are Used) Full scale proto-type laboratory cyclic load testing of the Energy Dissipating Shear Links shall be performed to verify the required ductility and strength of the link is achieved; to confirm the adequacy of the connection to towers; and to demonstrate that the Energy Dissipating Shear Links can be readily removed and replaced after it has reached the required maximum ductility demand as shown by analysis. The over-strength factor to be used when designing Energy Dissipating Shear Link capacity protected components shall be established by the full-scale testing. The quasi-static loading protocol for testing the Energy Dissipating Shear Links shall consist of three distinctive phases as summarized in Tables 1 to 3 and illustrated in Figure 1. The first and the second phase of the loading history reflect the actual cumulative link rotation demands under design earthquake loadings. Each of them representing a complete deformation history resulted from design SEE event in terms of the maximum link rotation and the total number of inelastic cycles. In Phase I the deformation sequence closely follows the response time history which contains large velocity pulses; whereas in Phase II the deformation sequence is arranged in the order of increasing rotation amplitude. Table 1: Energy Dissipating Shear Link Test Loading Sequence Phase I Load Step Link Rotation Amplitude (Radians) Number of Cycles Table 2: Energy Dissipating Shear Link Test Loading Sequence Phase Load Step Link Rotation Amplitude II (Radians) Number of Cycles Exhibit 2-13-A - Design Criteria Page 18