钢管混凝土桁式拱结构平面内受力性能试验研究

Experimental study on in-plane mechanical behavior of concrete-filled steel tubular truss arch

为分析钢管混凝土桁式拱结构的受力性能和破坏形态,进行了钢管混凝土桁式拱模型的试验研究。结果表明:钢管混凝土桁式拱结构节间直腹杆受到较大的竖向力,产生塑性变形,且随着竖向力的增大,直腹杆塑性变形节间增多,塑性变形区域沿拱轴向发展,内力重分布;在达到极限荷载前,桁式拱表现出了较好的整体性,没有出现节点破坏;达到极限荷载时,跨中至四分点附近截面处的节间直腹杆端部屈曲;继续加载后斜腹杆出现端部剪切破坏,最后弦管出现压弯失稳破坏;试验全过程中,桁式拱结构各弦管均未出现开裂现象,也未出现焊接节点或相贯区域破坏。同时,在试验研究的基础上,分析比较了钢管混凝土桁式拱结构、桁梁以及格构柱的受力特性和破坏形态,结果表明,钢管混凝土桁式拱结构的破坏模式与格构柱和桁梁存在较大的不同,桁式拱节间直腹杆受到较大的竖向力,因此,建议实际工程中应对钢管混凝土桁式拱腹杆的受力进行计算与校验。

In order to study the mechanical behavior and failure mode of concrete-filled steel tubular（ CFST） truss arch bridge,a test of CFST truss arch structures was conducted. The results indicate that the straight web members bear very huge loads that induce plastic deformation,and the truss arch has a preferable integrity before ultimate load,but more straight web members enter into plastic status with the increase of loads. The plastic area developes along arch axial direction,which induces redistribution of internal force. However,local buckling happens eventually at ends of straight web members from arch crown to quarter spans at ultimate load. As the loading further increases,the carrying capacity decreases and diagonal web members crack at ends, which leads to the instability failure.Nevertheless,the chords and welding joints of CFST arch rib do not crack during the loading process,and the areas of intersecting junction do not fail. At last,the comparison of mechanical behavior and failure mode of truss arch,truss girder and laced column were carried out based on the test. The results show that they are different and the web members for truss arch undergo very large vertical load,thus the design and checking of web members of CFST struss arch is necessary in practical engineering.