节点刚度对空间管桁架拱动力性能影响的研究

Study on the influence of joint stiffness on the dynamic performance of space tube truss arch

为研究相贯节点刚度对空间管桁架拱动力性能的影响,在节点域板壳单元与弹簧单元的动力性能一致性得到验证的基础上,建立节点域精细化弹簧模型,采用材料与几何非线性有限元法分析结构模态与地震时程响应。以跨度为50m,矢跨比为0.29的倒三角形截面空间管桁架拱为算例,结果表明:节点域弹簧模型的基频比普通模型低8.81%。加速度峰值为0.4gal的各向地震作用下,节点未进入塑性状态,节点处引入弹簧单元能有效地考虑节点的半刚性,相对于理想刚接的情况,节点位移响应相差不大,而轴力响应较为明显,水平地震作用下结构的内力增大了25.53%,竖向地震作用下结构的内力增大了4.89%,三维地震作用下结构的内力增大了22.49%。对不同跨度、矢跨比的空间管桁架拱进行了时程响应分析与讨论,计算结果表明:在大跨度管桁架拱节点设计分析中,节点刚度对结构动力性能的影响有较强的敏感性;节点刚度对不同矢跨比管桁架拱动力响应的影响与地震波的输入方向有关,此类结构在强震作用下,不宜采用未考虑节点刚度的模型进行动力响应分析。

In order to study the effect of intersecting joint stiffness on dynamic performance of space tube truss arch, a refined spring model is established based on the consistency of dynamic performance of plate shell element and spring element in joint domain, and the structural modal and seismic time-history response are analyzed by material and geometric nonlinear finite element method. Taking an inverted triangular space tube truss arch with a span of 50 m and a span ratio of 0.29 as an example, the results show that the fundamental frequency of the spring model is 8.81% lower than that of the rigid model. When the peak acceleration is 0.4 Gal, the joints do not enter the plastic state, and the introduction of spring element at the joints can effectively consider the semi-rigid joints. Compared with the ideal rigid joints, the displacement response of the joints is not different, but the axial force response is more obvious, and the internal force of the structure increases by 25.53% under the horizontal earthquake. The internal force of the structure under vertical earthquake action increases by 4.89%, and under three-dimensional earthquake action increases by 22.49%. The time-history response of space tube truss arch with different span and span ratio is analyzed and discussed. The calculation results show that the stiffness of space tube truss arch has a strong sensitivity to the dynamic performance of structure in the design and analysis of large-span tube truss arch joints. The influence of joint stiffness on dynamic response of tube truss with different span ratio is related to the input direction of seismic wave. It is not suitable to use the model without considering joint stiffness to analyze dynamic response of such structure under strong earthquake.