Structural performance evaluation of arch type long span highway bridge

This paper describes an arch type long span highway bridge, its finite element modeling, experimental measurements, finite element model updating using some uncertain parameters, and structural performance evaluation before and after model updating. For this purpose, Birecik Highway Bridge located on the 81st km of Sanhurfa-Gaziantep state highway over Firat River in Turkey is selected as a numerical example. The bridge consist of five arches, each of arch has a 55 m main span. The total bridge length is 300 m and width of bridge is 10 m. The initial finite element model of the arch type long span highway bridge is modelled using SAP2000 program to extract the analytical dynamic characteristics. Operational modal analysis method is used to. extract dynamic characteristics using enhanced frequency domain decomposition method. Obtained dynamic characteristics are compared with each other and finite element model of the bridge is updated to reduce the differences by changing of some uncertain parameters such as section properties, damages, boundary conditions and material properties. At the end of the study, structural performance of the highway bridge is determined under dead load, live load; and dynamic loads before and after model updating to specify the updating effect. Displacements, internal forces and stresses are used as comparison parameters. From the study, it is seen that the ambient vibration measurements are enough to identify the most significant modes of long span highway bridges. Maximum differences between the natural frequencies are reduced averagely from 49.1% to 0.6% by model updating. A good harmony is found between mode shapes after finite element model updating. It is demonstrated that finite element model updating has an important effect on the structural performance of the arch type long span highway bridge. Maximum displacements, axial forces, bending moments and compressive stresses are reduced 35.7%, 38.9%, 47.05%, and 29.6%, respectively.