轮辐式桁架弦支穹顶结构力学性能模型试验研究

Model test study on mechanical performance of spoke truss suspend-dome structure

轮辐式桁架弦支穹顶结构是近年来在传统弦支穹顶基础上发展而来的一种新型结构体系。它将上部网壳优化为空间辐射状管桁架结构,下部延续采用拉索结构,二者通过竖向撑杆连接形成自平衡体系,既保留了传统弦支穹顶结构跨越能力强、造型优美的优点,又解决了大跨结构整体刚度弱、稳定性差的问题。为研究轮辐式桁架弦支穹顶结构的静力性能及动力特性,制作了1∶10比例结构缩尺模型。开展了多工况分级静力加载试验、局部索力松弛试验及结构自振特性试验,分别得到了该结构在不同荷载作用下杆件的轴力及位移变化规律及自振频率的分布特征。结果表明:设计的加载方案满足试验精度要求;在均布荷载作用下,主桁架上弦杆及下弦杆始终为受压状态,中间杆件随着荷载增加由受压逐渐转为受拉,环杆最内侧杆件承受压力最大;各杆件内力随荷载值增加呈线性增长,节点位移及索力值变化均匀,结构在设计荷载范围内处于弹性阶段,整体协调变形能力较强。现场实测得到模型基频为7.965Hz,前10阶振型呈对称形态,且以整体振型为主,该结构与传统弦支穹顶结构相比刚度更大、稳定性更强。

The spoke truss suspend-dome structure is a new type of structural system developed from the traditional suspend-dome in recent years.It optimizes the upper reticulated shell into a spatial radial pipe truss structure,and the lower part continues to adopt a cable structure.The two are connected by vertical struts to form a self-balanced system,which not only retains the advantages of traditional suspend-dome structure,such as strong spanning ability and beautiful shape,but also solves the problem of weak overall stiffness and poor stability of large-span structure.In order to study the static performance and dynamic characteristics of the spoke truss suspend-dome structure,a 1∶10 scale model of the structure is made.The multi-condition static loading test,local cable force relaxation test and structural natural vibration characteristic test are carried out,and the axial force and displacement variation law of the structure under different loads and the distribution characteristics of natural vibration frequency are obtained respectively.The results show that the designed loading scheme meets the requirements of test accuracy.Under the action of uniform load,the upper chord and lower chord of the main truss are always in compression state,the middle member gradually changes from compression to tension with the increase of load,and the innermost member of the ring bar bears the maximum pressure.The internal force of each member increases linearly with the increase of load value,and the node displacement and cable force change evenly.The structure is in the elastic stage within the design load range,and the overall coordinated deformation ability is strong.The field measurement shows that the fundamental frequency of the model is 7.965Hz.The first 10 modes are symmetrical and dominated by the overall mode.Compared with the traditional suspend-dome structure,the structure has greater rigidity and stronger stability.