English abstract
Observations from real fires have demonstrated the beneficial effects of connection on the survival time of structural members in fire. Although experimental tests provide the best means to study the joint behavior in fire, they are limited in number partly on the virtue of their high costs and limitations on the size of the furnaces used. Also joint tests conducted are primarily focused on establishing the moment-rotation relationships of isolated joints and the comprehensive understanding of the joint behavior in fire cannot be achieved based on the outcomes from experimental fire tests alone. The Finite Element Method (FEM) provides an excellent alternative in analyzing the joint behavior in fire to an acceptable degree of accuracy. This thesis presents a 3D Finite Element model developed to model the behavior of flexible endplate beam-column composite connections in fire using the general purpose Finite Element commercial code ABAQUS 6.10. Two types of flexible end-plate composite joints were modeled. The connection components for bare steel was modeled using a four noded tetrahedral element coupled with temperature and displacement using the ABAQUS standard analysis procedure. Modeling of concrete was carried out using the damaged plasticity parameters. Anti crack mesh was modeled using a truss element. Degradation of the steel properties with increasing temperature was in accordance with EC3 recommendations. Comparison between the Finite Element analysis and two isolated flexible end-plate composite connections under group 4 and group 5 fire tests were compared with respect to temperature-rotation results and failure mode of the connections. The developed model produced good results that compare well with the experimental results.
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