基于日照阴影识别的桁式拱肋三维温度场模拟方法

为精确高效地识别桁式拱肋的阴影分布范围并准确计算日照温度场，在传统三维温度场计算方法的基础上，引入三角形重心坐标及栅格加速结构，形成一套高效三维温度场模拟方法。首先，将光线追踪技术的阴影识别算法嵌入ABAQUS软件的自定义热源(DFLUX)子程序，实现了三维日照温度场的数值模拟，给出了详细的计算流程并验证了该方法的准确性；其次，选取高效的相交算法与合理的栅格划分方式解决了复杂结构桥梁阴影识别计算量庞大、计算效率低下的问题；最后，利用该方法计算了桁式拱肋的日照温度场并量化了温度效应。结果表明：提出的模拟方法可以实现阴影的精确识别与结构三维温度场的准确计算，通过引入基于栅格加速结构的三角形重心坐标法可以有效减少阴影识别的计算量，显著提升计算效率;日照阴影对桁式拱肋温度场及温度效应的影响不容忽视，考虑日照阴影后：下弦杆温度纵向波动十分显著，且波动幅度随着太阳辐射强度的增强逐渐增加，相邻的光照、阴影区域最大温差达13.0 ℃,拱肋竖向位移减小19%，上弦管上缘应力最大增加12.9 MPa，下弦管上缘由受压状态转变为受拉状态，应力差值达39.1 MPa;桁式拱肋的日照温度效应十分突出,日照温度作用下拱顶位移变化幅度达76 mm，较钢管混凝土拱肋拱圈施工允许误差大26 mm,最大温度应力达58.7 MPa，为恒载效应的3倍，叠加温度效应后钢管最大初应力为110 MPa，为空管稳定承载应力的32%;提出的模拟方法在桁式拱肋日照温度效应分析中得到了成功应用，亦可应用于大跨复杂结构的施工线形精细化控制、健康监测数据的温度响应分离及结构损伤识别中的温度模态频率剔除等多个场景。

Three-dimensional Temperature Field Simulation Method of Truss Arch Rib Based on Sunshine Shadow Recognition

In order to accurately and efficiently identify the shadow distribution range of truss arch ribs and accurately calculate the sunshine temperature field, based on the traditional three-dimensional tem-perature field simulation method, a set of efficient three-dimensional sunshine temperature field simula-tion method was formed by introducing the triangle barycenter coordinates and grid acceleration structure. Firstly, the shadow recognition algorithm of ray tracing technology was embedded into the DFLUX subroutine of ABAQUS software, and the numerical simulation of three-dimensional sunshine temperature field was realized. The detailed calculation flow was given and the accuracy of this method was verified. Secondly, the efficient intersection algorithm and reasonable grid division method were selected to solve the problems of huge computation and low computational efficiency in shadow recognition of complex bridges; Finally, the sunshine temperature field of truss arch rib was calculated by this method and the temperature effect was quantified. The results show that the simulation method proposed in this paper can realize the accurate recognition of shadows and the accurate calculation of three-dimensional temperature field of structures. By introducing the triangle center coordinate method based on grid acceleration structure, the calculation amount of shadow recognition can be effectively reduced and the calculation efficiency can be significantly improved. The influence of sunshine shadow on the temperature field and temperature effect of truss arch rib can't be ignored. After considering sunshine shadow, the longitudinal fluctuation of the temperature of the lower chord is very significant, and the fluctuation range gradually increases with the increase of solar radiation intensity, and the maximum temperature difference between adjacent illumination and shadow areas reaches 13.0 ℃; The vertical displacement of the arch rib decreases by 19%, the stress on the upper edge of the upper chord tube increases by 12.9 MPa, and the upper edge of the lower chord tube changes from compression to tension with a stress difference of 39.1 MPa. The sunshine temperature effect of truss arch rib is very prominent: the variation range of vault displacement under sunshine temperature is 76 mm, which is 26 mm larger than the allowable error of arch ring construction of concrete-filled steel tube arch rib, and the maximum temperature stress is 58.7 MPa, which is three times of dead load effect, after considering the temperature effect, the maximum initial stress of steel pipe is 110 MPa, which is 32% of the stable bearing stress of empty pipe. The simulation method proposed in this paper has been successfully applied to the analysis of sunshine temperature effect of truss arch ribs, and can be applied to many scenarios such as fine control of construction alignment of long-span complex structures, separation of temperature response of health monitoring data and elimination of temperature modal frequency in structural damage identification.