Damages Inspection and Finite Element Model Analysis of Static and Dynamic Factors of Steel Girder-Concrete Composite Span Due to Vehicles Live Load and Loads Combination

Abstract

This study's primary goals are to: Identify any damage that may have happened to the structural elements of steel I-girder-concrete composite spans; determine the static responses according to the influence of the vehicle and service loads (loads combination case) using numerical static analysis FEM using CSI-Bridge Ver. 25; measure the natural frequency of the bridge structure according to the influence of self-weight of the structure using modal analysis; determine the dynamic responses due to vehicle live load using numerical dynamic time history analysis by using Finite Element Method (FEM); assess the constructional effectiveness of bridge structures and identify methods for reinforcing and repairing damaged structural elements. Damage inspection results of steel I-girder span showed that the damage is not severe in the structural parts of span. Steel I-girders span shows no signs of rust or corrosion, but the main problem is in the expansion joints and they need to be repaired or replaced. Under the effect of vehicles live load and load combinations, maximum tensile stress appeared at the bottom of steel I-girder span, which was 13.56MPa and 86MPa respectively, lowering than the allowable value of tensile stresses from AASHTO LRFD BRIDGE, which is equal to 207MPa. The maximum deflection in the downward direction due to vehicles load and load combination was 10.9 mm and 91 mm, respectively. Meeting the allowable deflection values of 70 mm (live load) and 112 mm (loads combination). The Finite Element dynamic analysis described that the average value of vibration frequency is 6.42Hz. Compared with natural frequency, it is higher than 2.95Hz, indicating that the span of bridge will face vibration issues because this span has a long length. Therefore, this study recommended that to add more steel girders with more diaphragms (cross beams) to reduce the vibration of bridge span.