矩形钢管混凝土组合桁梁连续刚构桥实桥试验

为了研究矩形钢管混凝土组合桁梁桥这种主梁由矩形钢管混凝土桁架和混凝土桥面板组成的新桥型的力学性能，以中国首座矩形钢管混凝土组合桁梁桥为对象开展了实桥试验。试验桥孔跨布置为24 m+40 m+24 m，结构体系为连续刚构。试验采用400 kN加载卡车3辆，共进行了3个荷载工况12个加载步的加载，对试验桥的整体力学性能、矩形钢管混凝土杆件力学性能以及桥面板有效宽度进行了研究。试验结果表明：在荷载效率为1.90~3.05的超载工况下各控制杆件的轴力-应变及荷载-位移实测数据线性关系显著，试验桥在加载过程中始终处于良好的弹性工作状态；实测受压钢管混凝土下弦杆钢管与管内混凝土荷载的分配符合二者的轴向抗压刚度比例关系；由于矩形钢管混凝土管壁内设置了纵向PBL加劲肋（开孔钢板加劲肋），其在开孔区域形成混凝土榫，大幅提高了矩形钢管混凝土杆件的抗拉刚度，使其可达受压杆件刚度的80%；两主桁之间桥面板实测有效宽度与既有文献研究结果符合良好，且剪力滞效应在节点处比节间处表现得更为明显。

Field Test of Rectangular Concrete Filled Steel Tubular Composite Truss Bridge with Continuous Rigid System

The main girder of the rectangular concrete-filled steel tubular (CFST) composite truss bridge consists of a rectangular CFST truss and concrete deck. To investigate the mechanical behavior of this new bridge type, field tests were performed on the first rectangular CFST composite truss bridge in China. The span arrangement of the testing bridge was (24+40+24) m, and the structural type of bridge was a continuous rigid system. 3 trucks of weight 400 kN were used as the loading vehicles, and 3 test conditions with 12 loading steps were deployed. The whole mechanical behavior of the bridge, the rectangular CFST members, and the effective width of concrete deck were investigated. The test results show that the tested data of the axial force strain for the controlled members and the load displacement had significant linear relationships under overloading conditions with the load efficiency ratio ranging from 1.90-3.05; the testing bridge remained well within the elastic stage during the entire loading process. The measured load distribution between the in-filled concrete and steel tube for the compressing CFST member in the lower chord is similar to the relationship of the axial compression stiffness ratio. The longitudinal perfobond leister stiffeners (PBL stiffeners) were arranged in the steel tube of the CFST members, subsequently the concrete tenon was formed at the perfobond area and this could greatly increase the axial tensile stiffness of the rectangular CFST member to 80% of the compression member's stiffness. The tested effective width of the concrete deck between the chords coincides well with the value presented in the existing literatures. The shear lag in the concrete slab is more obvious on the truss joint compared to that at the midsection of the segment.