火灾作用下钢筋混凝土托梁转换结构模型变形有限元分析

Deformation analysis of reinforced concrete structure with transfer girder under fire

采用ABAQUS有限元分析软件,对一榀4层底部大空间钢筋混凝土梁托柱转换结构模型施加标准升温及竖向荷载的共同作用,进行了8种受火工况下转换结构模型的变形计算,分析了模型中托梁和相邻边柱的位移与标准升温时间的关系曲线。计算结果表明,在不同受火工况下,随着标准升温时间的增加,转换结构模型均产生了常温竖向荷载变形基础上的附加变形。转换结构模型底部托梁的挠度值在升温前期的60 min内增长较快,之后逐渐减缓。沿托梁跨度方向的挠度曲线形状受受火房间布置位置的影响,在非对称受火房间布置工况下,模型对称轴受火房间一侧的托梁挠度偏大。火灾作用下转换结构模型两侧边柱在受火楼层横梁位置处向外凸出的变形明显大于其他楼层。对于仅在模型对称轴的一侧布置受火房间的工况,两侧边柱的侧移从上到下发生着剧烈的变化,表现出在不对称受火房间布置情形下,转换结构中会产生剧烈的相互作用。

The nonlinear FEA software ABAQUS is used to analyze the deformation of a model which is exposed to fire and subjected to vertical loads. This model is a four-story reinforced concrete structure with large space at bottom.Based on the simulation results of eight fire cases,the displacements of the transfer girder and heating time curves were analyzed. The numerical results show that,under different fire cases,with the increase of the heating time,the transfer girder structure models produce complicated additional deformations based on the deformations under vertical loads at room temperature. The deflections of the transfer girder grow fast in 60 minutes of fire duration,and then slow down gradually. The shape of the deflection curves along transfer girder span is influenced by the layout of fire rooms.Under the asymmetric fire cases,the deflections of the transfer girder are larger on the side on fire. The lateral displacements outward of side columns in burning floors are significantly larger than other floors. Under the asymmetric fire cases,lateral displacements of side columns change drastically. It shows that,under the asymmetric fire cases,the transfer structure models will produce a significant interaction.