基于双向渐进结构优化算法的预制拼装箱梁剪力键设计研究

Design of Shear Keys for Precast Segmental Box Girders Based on Bidirectional Evolutionary Structural Optimization Algorithm

为研究单项和多项荷载组合作用下节段预制拼装箱梁接缝处剪力键受力状况,以郑州南四环全预制装配高架桥为背景,采用Abaqus软件和双向渐进结构优化(BESO)算法,建立典型箱梁节段分析模型,研究剪力键在单位轴力、剪力、扭矩、弯矩和不同荷载组合作用下的布置规律。结果表明:轴力作用时剪力键应布置于顶板;剪力作用时剪力键应布置于腹板和底板;扭矩作用时剪力键应布置在顶板、腹板交接处和腹板外侧;横桥向弯矩作用时剪力键应布置于顶板、腹板下侧和底板;竖向弯矩作用时,剪力键应布置于顶板翼缘。轴剪组合作用下,当剪力占比小于50%时,轴力对剪力键布置起控制作用;当剪力占比达95.24%时,剪力对剪力键布置起控制作用。弯剪组合作用下,当剪力占比超过4.76%时,剪力对剪力键布置起控制作用;当剪力占比小于0.50%时,横桥向弯矩对剪力键布置起控制作用。扭剪组合作用下,当剪力占比超过0.10%时,剪力对剪力键布置起控制作用。预制拼装箱梁剪力键布置受荷载类型及荷载组合影响显著,应考虑不同位置剪力键的实际受力状况进行设计。

This study investigates the load bearing behavior of shear keys in the cast-in-place(CIP)stitches of the precast segmental box girders responding to single load and load combinations.The viaduct carrying a section of the South Fourth Ring Road in Zhengzhou city is used as a case.Considering the load bearing behaviors and functions of the shear keys,finite element models of the typical box girder segments were developed in Abaqus,together with the bidirectional evolutionary structural optimization(BESO)algorithm,to figure out the arrangements of shear keys under different loading conditions,including unit axial forces,shear forces,torsional moments,bending moments and different load combinations.As per the analysis,the shear keys should be arranged in different places of the box girders under different forces,specifically arranged in top slabs under axial forces,in webs and bottom slabs under shear forces,in junction of top slabs and webs as well as exterior of webs under torsional moments,in top slabs,lower parts of webs and bottom slabs under lateral bending moments,and in the flanges of the top slabs under vertical moments.Under the combined action of axial and shear forces,especially when the proportion of the shear forces is less than 50%,the axial forces govern the arrangement of shear keys.When the proportion of shear forces reaches 95.24%,the shear forces dominate the arrangement of shear keys.Under the combined action of bending moments and shear forces,with the proportion of shear forces exceeding 4.76%,the shear forces control the arrangements of the shear keys,while the lateral bending moments play a dominant role when the proportion of shear forces is less than 0.50%.Under the combined action of torsional moments and shear forces,when the proportion of shear forces surpasses 0.10%,shear forces dictate the arrangement of shear keys.The types of loads and load combinations are critical to the arrangement of shear keys.The arrangement of shear keys in the CIP stitches of precast segmental box girders should be designed considering the actual loading conditions of the shear keys in different locations.