六杆四面体单元端板式节点受力性能研究

提出了一种可满足六杆四面体单元装配化施工要求的节点形式——端板式节点.即六杆四面体单元的弦杆与腹杆相贯焊接于端板,通过端板上的高强螺栓实现单元之间的连接.设计并制作了2个足尺节点模型,分别考察其在压弯和轴拉荷载作用下的受力性能,得到了端板节点的位移、应变发展特点及破坏形态.采用ABAQUS软件进行考虑接触非线性的有限元分析,得到了杆件、端板及高强螺栓的应力和变形.试验和有限元分析结果表明:在压弯荷载作用下,端板节点发生杆件屈曲和近节点域处鼓曲变形破坏,且杆件屈曲破坏先于节点域鼓曲破坏;节点域高应力区主要集中在三杆相贯焊接形成“谷底”处;高强螺栓在整个加载过程中最大应力约为其屈服应力的10%.轴拉荷载作用下,节点发生端板拉屈破坏;位于缺口两侧的高强螺栓发生拉弯变形,建议适当增设加劲肋和增加端板厚度,以提高端板刚度.通过数值计算得到的端板节点宏观变形、荷载-位移曲线及部分荷载-应变曲线均能与试验结果较好吻合,反映了数值分析模型的有效性与准确性.

Study on mechanical behavior of end-plate joint of six-bar tetrahedral units

An end-plate joint which could meet the needs of prefabricated construction for six-bar tetrahedral units is presented. Namely, the chord of the six-bar tetrahedral unit and the web are welded to the end plate, while high-strength bolts are used to connect the end plates between units.. Two full-scale specimens were designed and fabricated to investigate the mechanical behavior of end-plate joint under axial tension and combined compression and bending. The development characteristics of the displacement and strain of the end-plate joint as well as the corresponding damage modes were achieved. Finite element analysis (FEA) with modeling nonlinear contact interaction was carried out by using ABAQUS. The stress and deformation of bars, end-plates and high-strength bolts were presented. It is observed from test and FEA results that the buckling of bars followd with the local buckling near joint region under combiend compression and bending. The high-stress zone locates at the “valley bottom” formed by weld intersecting of three bars. The maximum stress in high-strength bolts is about 10% of its yield strength during the whole loading process. Under the axial tensile load, the buckling of end-plates and the bending deformation of high-strength bolts are observed . Stiffeners and end-plates with higher thickness are suggested to improve the stiffness of the end-plate. The overall deformation, load-displacement curves and partial load-strain curves of the end-plate joints obtained by numerical calculation are agree well with the test results, indicating the validity and accuracy of the established numerical model.