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Edgewater Creek Bridge Replacement November 2023 137 6-02.3(19).INST1.DOCX 1 Section 6-02.3(19) is supplemented with the following: 2 3 6-02.3(19).OPT1.DOCX 4 (******) 5 Seismic Isolation Bearings 6 7 Description 8 The work shall consist of configuring, manufacturing and testing seismic 9 isolation bearings (isolators) in accordance with the contract plans and 10 specifications and the current edition of the AASHTO Guide Specifications for 11 Seismic Isolation Design, with interims. The isolators shall consist of the 12 isolators with top and bottom mounting plates. Additional items such as sole 13 plates, masonry plates and anchor rods shall be considered part of the isolation 14 bearing assembly, and may or may not be supplied by the isolation bearing 15 supplier, at their discretion. Contractor shall note that the isolators may require 16 significant lead-time to obtain. 17 18 The isolation bearing system is a key structural component of the bridge, and 19 must function successfully during an earthquake at any time throughout the life 20 of the bridge, while also performing reliably under service loads with no 21 maintenance. To ensure these criteria are met, stringent requirements are 22 imposed in this specification. 23 24 The isolator dimensions shown on the plans are based on one possible isolator 25 configuration, for the purpose of determining beam seat elevations and 26 connection details. Final isolator configurations may vary from that shown and 27 the Contractor is responsible for making any necessary adjustments in adjacent 28 elements to accommodate final isolator dimensions. The isolators shall meet 29 the limiting dimensions, if any, shown on the plans. 30 31 The structure has been analyzed and designed in accordance with the AASHTO 32 Guide Specifications for Seismic Isolation Design using a lead core elastomeric 33 isolation system. Approved suppliers of the lead core elastomeric isolation 34 system are not required to perform additional analyses. 35 36 Approved Suppliers 37 Suppliers of the isolation bearings shall have a minimum of 5 years of 38 experience in the design, fabrication and testing of lead-rubber seismic 39 isolation bearings. A list of completed projects shall be submitted 40 demonstrating past experience. 41 42 43 Alternate Systems or Suppliers 44 Alternate systems are not permitted. 45 46 Codes and Standards 47 The design and testing of the isolators shall conform to the applicable 48 provisions of the current edition of the following standards. 49 50 A. AASHTO Guide Specifications for Seismic Isolation Design (2014) 51