西北大温差地区钢-混组合梁温度效应及其适用公式OA北大核心

To examine the temperature distribution and effects on steel-concrete composite girder bridges in the northwest region's significant temperature variations,and to establish a local applicable formula for temperature gradient effects,this study presented a 1∶5 scale model of a steel-concrete composite girder.The model was inspired by the main bridge of the Sang Yuan Zi Yellow River Bridge in the Lanzhou area and undergoes an experimental temperature field analysis.The research concentrated on the distribution patterns of the temperature field and the temporal characteristics of steel-concrete composite beams under two distinct temperature effects:solar radiation and abrupt cooling,both within a large temperature fluctuation context.Analyzing the temperature field tests on these beams,the study delineated how the temperature of steel-concrete composite beams varied over time under these conditions and identifies the most adverse calculation formula for the temperature gradient load.Findings indicate that solar radiation has a more pronounced impact on the temperature of steel-concrete combined beams than sudden cooling.The temperature variation over time in steel-concrete beams,under solar radiation,deviates from a sinusoidal pattern due to the'shading effect',leading to a noticeable inflection in the temperature curve of the steel beam's web.A temperature differential,up to 4.5℃,is observed at the interface where the concrete deck meets the steel girder in the composite bridge.Additionally,the concrete deck's temperature field changes lag behind ambient temperature shifts.The study introduces a quadratic parabolic model to accurately calculate the most unfavorable vertical temperature gradients,both positive and negative,which is well-suited for the northwest region's substantial temperature differences.This model enhances the continuity between the concrete deck and steel girder,ensuring high precision and reliability.The insights gained from this research are instrumental for the calculation of temperature gradient loads and the structural design of similar steel-concrete composite beam projects in China's northwestern regions,where significant temperature variations occur.