TranTech Engineering LLC 5/15/2019

Task 7 Concept Design Report (CDR) The CONSULTANT will prepare a Concept Design Report (CDR) providing description of the detailed structural analysis used in the determination of seismic vulnerabilities, and calculated section capacity/demand ratios for both as-built and post-retrofit conditions (on proposed parts/members to be retrofitted identified following as-built condition analyses.) Construction cost estimate and preliminary retrofit plans will be included in the Concept Design Report as appendices. A constructability review of the proposed retrofits will be conducted by the CONSULTANT to inform the selection of the proposed retrofits as well as the construction cost estimates of those retrofits. Seismic Analysis and CDR Preparation Assumptions: • Elastic analyses will be performed as part of this SCOPE during a design seismic event. This assessment will be partly based on experience and engineering judgment. • 2 Structural models (i.e., Spine and 3-D) will be developed based on the as-built drawings, with visual field verification of elements above ground and accessible without special equipment. For each model, two conditions of soft for displacement demand (i.e., liquefied) and rigid for force demand will be studied. • Structural models will utilize a single spine representing the bridge superstructure, with additional frame elements included to represent crossbeams, columns, and spread footings. Spread footing foundation springs will be established in accordance with procedure outlined in the FHWA Seismic Retrofitting Manual and BDM. Abutments and walls may be modeled with frame or shell elements, at the CONSULTANT's discretion. • Per AASHTO Guide Specs, seismic analyses are performed for the design 1,000-yr event based on the as-built conditions. • Foundation analysis will be based on The AASHTO Guide Specifications for LRFD Seismic Bridge Design. • Live load concurrent with seismic demands will not be considered in the analysis. • In determining seismic responses, effective member stiffness will be determined based on the FHWA Retrofitting Manual guidelines. • Expected material properties will be used for all elements in the analysis. Nominal material properties will be used in design or retrofit items only. • Pushover analysis will be conducted as described in Method D2 of the FHWA Retrofitting Manual: for the 1,000-yr analysis, concrete strain at plastic hinging will be limited to 0.005. Maple Heights Bridge Seismic Retrofit 19