Assessment of the Bill Emerson Memorial Bridge - FTP Directory ...

4. Finite Element Modeling of Bill Emerson MemorialCable-stayed Bridge4.1. GeneralDue to rapid developments in computational mechanics, FE modeling has become one ofthe most powerful tools used in the analysis and design of large-scale bridges. A FE modelcan be the convenient and accurate idealization of a complicated structure in civilengineering. In order to successfully establish a bridge FE model, assumptions must bemade to simplify the process of modeling. Additionally, due to structures’ complexity,uncertainty may exist in material and geometric properties. Therefore, the calculatedresults from a FE model must be properly verified by various means, particularly with fieldmeasurements.In cable-stayed bridges, there exist two types of nonlinearity: geometrical and material.Geometrical nonlinearity is an important feature under operational loads (Guido, 1999; Huet al., 2006). Depending on design specifications and construction process, a cable-stayedbridge model may have to be analyzed to determine its deflected position under dead loads.Geometrical nonlinearity is associated with:♦ The sagging effect of inclined stay cables which governs the axial elongation;♦ The effect of relatively large deflections of the whole structure due to itsflexibility;♦ The action of compressive loads in the slab and in the towers.On the other hand, Ren and Makoto (1999) studied the elastic-plastic seismic behavior oflong span cable-stayed steel bridges and concluded that geometric nonlinearity had littleinfluences on the seismic response behavior of the example bridge. Nevertheless, thesagging effect of stay cables is herein taken into account in the FE model of the BillEmerson Memorial Cable-stayed Bridge.As one of the most powerful engineering design and analysis software, SAP2000 is chosento model and analyze the Bill Emerson Memorial Cable-stayed Bridge. This software hascapability of modeling pre-stressed cables for their sagging effect and of simulating pilefoundations. In this report, a 3-D numerical model of the Bill Emerson Memorial CablestayedBridge is established using the SAP2000 version 10 software.4.2. Bridge geometryThe geometry of the cable-stayed bridge was modeled according to the as-built drawings:Steel Cable-Stayed Main Span Unit (SCMS) or Approach Spans (AS) Cape GirardeauCounty, Missouri to Alexander County, Illinois, with necessary updated modifications inconsultation with the Missouri Department of Transportation. The key dimensions andgeometry of bridge members were extracted from the plans as detailed in Table 4.1.41