| As a new type of wall, multi-ribbed composite wall is widely used in construction structure in recent years. The occurrence of fire, however, obviously reduces the service life of the wall, poses a threat to safety of human and property. As mechanical material of this wall, this paper studies mechanical properties of lightweight aerated concrete block after high temperature, with the research background of multi-ribbed composite wall. Based on this research, a further work will be done to study mechanical properties of the multi-ribbed composite wall cell after high temperature.In this paper, a series of axial compression tests are conducted to test the mechanical properties of lightweight aerated concrete after high temperature, and then the mechanical model is used to simulate the temperature field and residual bearing capacity of the multi-ribbed composite wall cell after high temperature. The main contents are as follows:(1) Through axial compression test of lightweight aerated concrete after high temperature, the relationships between the mechanical properties with temperature are obtained, including compressive strength, elastic modulus and peak strain. Analyzing the stress-strain curve under different temperatures, a constitutive model of lightweight aerated concrete after high temperature is proposed.(2) According to the thermodynamic performance of each material, the numerical analysis is established to the multi-ribbed composite wall cell. The temperature field contours are obtained in different fire loads. The temperature of each node can be studied through different heating time. The temperature curve of node is related to the distance from node to the surface in fire. The heating curves of nodes are similar with ISO international heating curves when nodes near the surface in fire. Otherwise, the heating curves have deviations.(3) Through numerical analysis about residual bearing capacity of the multi-ribbed composite wall cell after high temperature, the relationships are proposed between residual bearing capacity and different heating time under different conditions of fire. The side by the fire is earlier to achieve ultimate load under the vertical displacement load. Because of the damage by the fire, the multi-ribbed composite wall cell is more likely to occur out-plant displacement when it is under the vertical displacement load. Therefore, in the actual project we should pay more attention to one side of multi-ribbed composite wall by the fire. |
