横向分段施工预应力混凝土斜箱梁极限承载能力研究

Study on Ultimate Bearing Capacity of Transversely Segmental Constructed PC Skew Box Girder

为了分析横向分段施工预应力混凝土斜箱梁(简称分段合成斜箱梁)与整体浇注预应力混凝土斜箱梁(简称整体浇注斜箱梁)极限承载能力差异,建立分段合成斜箱梁和整体浇注斜箱梁的两个大比例试验模型;在两个模型的关键截面布设应变和挠度测点,采集两者在分级加载试验过程的挠度、应变数据,观测混凝土开裂情况。对采集的数据整理分析,比较两者在加载过程中结构的开裂情况、极限承载能力大小和受力性能的差异。根据结构受力特点,提出分段合成斜箱梁极限承载力的有限元分析方法;应用有限元程序ANSYS对两个试验模型的极限承载能力进行分析,分别与试验结果进行比较,验证了有限元模型的准确。通过试验和有限元比较分析,结果表明分段合成斜箱梁跨中截面湿接缝的混凝土先于整体浇注斜箱梁混凝土开裂,整体浇注斜箱梁梁肋底部混凝土先于湿接缝对应位置的混凝土开裂,且前者的开裂荷载低于后者,但两者的极限承载力相差甚微,基本相等;通过有限元分析斜交角和抗弯抗扭刚度比两个参数,表明整体浇注斜箱梁的极限承载能力随着斜交角的增加而增大,随着抗弯抗扭刚度比的减小而增大,但增大幅度较小。

In order to analyze the difference between the ultimate bearing capacity of transversely segmental constructed prestressed concrete skew box girder (TSCPCSBG)and that of integral constructed prestressed concrete skew box girder (ICPCSBG),large scale test models of the 2 skew box girders are built respectively.The measuring points are arranged on the key sections of both models.Hierarchical loading is adopted to collect the deflection and strain data of both models and observe the respective concrete cracking. The collected data are analyzed to find out the difference between both models in structure cracking,ultimate bearing capacity and mechanical performance.Based on the mechanical performance of the structure,the FE analysis method for the ultimate bearing capacity of TSCPCSBG is put forward.The ultimate bearing capacities of both models are analyzed with the FE program ANSYS,which are compared with the experimental results respectively,and the finite element models are verified to be accurate in this way.The results from the test and FE analysis show that the crack of the wet joint concrete in midspan cross-section of TSCPCSBG occurred earlier than that of ICPCSBG,the concrete crack at the bottom of the girder ribs of ICPCSBG occurred earlier than that of the corresponding position of wet joint,and the cracking load of TSCPCSBG is lower than that of ICPCSBG,but the ultimate bearing capacities of both models are of little difference.The skew angle and the flexural/torsional resistance stiffness ratio are also analysed with FEA model.It shows that the ultimate bearing capacity of ICPCSBG increased with the increase of skew angle and the decrease of flexural/torsional resistance stiffness ratio,but the increase is small.