铝合金板式节点网壳杆件壳体平面内计算长度分析

Study on effective length of members of aluminum alloy shells with gusset joints in shell plane

为获得铝合金板式节点网壳杆件的平面内计算长度,对5根网壳杆件进行轴心受压稳定承载性能试验。采用ABAQUS中的实体单元建立试件的有限元模型,通过反弯点法得出了杆件的计算长度。研究结果表明,铝合金板式节点的半刚性构造使得网壳杆件的平面内计算长度与其净长度有关。基于ANSYS软件平台,采用非线性弹簧单元COMBIN39建立了考虑铝合金板式节点半刚性的网壳模型。通过对不同荷载模式下网壳一阶屈曲荷载及杆件临界荷载的对比,发现压杆周围杆件受压时的刚度退化对其约束的削弱作用可使其计算长度系数放大约33%,因此杆件的受压刚度退化在稳定分析中不可忽略。通过对杆端约束刚度的推导和弹性稳定微分方程的求解,得到了考虑铝合金板式节点半刚性和周围杆件约束的网壳杆件平面内计算长度系数,并制成了供设计使用的计算用表,可为铝合金板式节点网壳杆件的设计提供依据。

To obtain the in-plane effective length of members of shells with aluminum alloy gusset （AAG） joints, an experimental program including five shell members under axial loading was carried out to investigate their stability. Finite element （FE） models were established in ABAQUS using solid elements to simulate the test specimens, and their effective lengths were derived using the inflection points. The research results reveal that the in-plane effective length of the members is related to their net length due to the semi-rigidity of AAG joints. Non-linear spring element COMBIN39 was adopted to establish a shell model considering the semi-rigidity of AAG joints in ANSYS. Based on the comparison on the first-order buckling load of the shells and the critical load of the members, it is found that the weakening of constraint due to the stiffness degradation of the compressive members can lead to an increase of effective length by up to about 33% , which cannot be ignored. Through the derivation of the constraint stiffness and the solving of the elastic stability equilibrium differential equation, an in-plane effective length factor table was derived considering the semi-rigidity of the joint and the constraint of the ambient members, which can provide foundation for the design of AAG shell members.