基于AP法的单层球面网壳结构地震倒塌破坏分析

在地震作用中，结构的薄弱部位构件可能会先发生初始失效，并导致结构在之后的地震中发生倒塌破坏。为研究在杆件初始失效下单层网壳结构的抗连续倒塌性能，通过增量动力分析方法（IDA 法）确定网壳结构薄弱区域分布规律及结构的动力响应，引入最大响应参数（应力、塑性应变、等效塑性应变等）杆件作为初始破坏杆件，采用备用荷载路径法（AP 法）分析剩余结构在之后的地震作用中产生的动力响应。结果表明：单层网壳结构地震薄弱区处于底部区域，且受地震影响较大。在地震作用下，处于薄弱区域的杆件初始失效会使结构节点最大竖向位移、 塑性杆件比例、总应变能等结构响应参数急剧增大，并且加速了结构的凹陷。由于杆件的初始失效，其两端节点发生较大塑性，周围杆件塑性发展明显，应重点关注处于地震薄弱区的杆件，该区域杆件若发生初始失效将对结构产生影响较大。

Seismic Collapse Analysis of Single‑Layer Reticulated Spherical Shell Structure Based on AP Method

Under seismic action, the weak components of a structure are highly likely to experience initial failures, leading to collapse in subsequent earthquakes. To study the progressive collapse resistance of single-layer reticulated spherical shell structures under initial member failure, the Incremental Dynamic Analysis (IDA) method was employed to analyze distribution of weak areas in the structures and their dynamic response. Maximum response parameters (stress, plastic strain, equivalent plastic strain, etc.) were introduced to identify initial failure members. The Alternate Path (AP) method was then used to analyze the dynamic response of the remaining structure under subsequent seismic actions. The results showed that the seismic weak areas of single-layer shell structures were primarily located at the base and were significantly affected by seismic forces. Under seismic loads, the initial failure of members in weak areas led to a sharp increase in structural response parameters such as maximum vertical displacement of nodes, plastic member ratio, and total strain energy, accelerating structural collapse. Due to the initial failure of members, significant plastic deformation occurred at both ends of the members, with evident plastic development in surrounding members. Attention should be paid to members in seismic weak areas, as initial failure in these areas will have a substantial impact on the overall structural integrity.