Analytical Prediction of Thermal Displacement Capacity of Integral Bridges Built on Sand

Abstract

In this research, analytical equations are developed to calculate the lateral displacement capacity and maximum length limits of integral bridges built on sand based on the low-cycle fatigue performance of the piles under cyclic thermal variations and the ultimate strength of the abutment under positive thermal variations. To formulate the displacement capacity and maximum length limits of integral bridges based on the low cycle fatigue performance of steel H-piles under cyclic thermal variations, first, H-piles that can accommodate large plastic deformations are determined based on their local buckling instability. Then, a low cycle fatigue damage model is used as a tool to formulate the maximum cyclic curvatures and corresponding bending moments that such piles can sustain. Next, this information is employed in static pushover analyses of two integral bridges to study the effect of various geometric, structural and geotechnical parameters on their displacement capacity as determined by the low-cycle fatigue performance of steel H-piles under cyclic thermal variations. The findings from these static pushover analyses are then used to formulate the displacement capacity and maximum length limits of integral bridges as determined by the low-cycle fatigue performance of steel H-piles under cyclic thermal variations. The results from the same static pushover analyses are also used to formulate the displacement capacity and maximum length limits of integral bridges as determined by the ultimate strength of the abutments under positive thermal variations. It is observed that the stiffness of the deck, height of the abutment, properties and orientation of the piles as well as the density of the sand affect the displacement capacity of integral bridges. It is also found that the maximum length limit of integral bridges ranges between 65 and 310 m based on the properties of the bridge and climatic conditions.