Study On Nonlinear Punching Shear Damage Process Imitation Of Thick Raft Foundation

The thick raft foundation is used in practical project because of its good globality, setting uneven settlement of groundwork, producing biggish space for basement.But in the design with the research in order to considering the combined action of raft foundation and the foundation soil body, make its stress case and punching shear mechanism very complexity, currently still have no precise analytic solution, mainly regard half experience and half theories as principle.And because the raft foundation size more big, it is difficult to do the field experiment, so this text make use of ADINA finite element program to carry on punching shear imitate and nonlinear analyzing to the raft foundation, and making a comparison with experiment result.On the base of numerous scholars to study on punching shear broken of slab column system connection, make use of ADINA finite element software to carry on nonlinear punching shear broken imitate to platform raft foundation for considering vertical load and vertical load with unbalance flexural moment respectively.Get the raft foundation's destruction and fracture feature, deformation, strain as well as distribution of foundamental reaction force under the different two kinds of application of load. Considering that different application of load has different impact on destructive conformation of raft foundation.For the punching shear calculation, making use of yield line theory and analogic beam method to carry on computation for raft foundation under vertical load with unbalance flexural moment respectively,making use of code formula to calculate punching shear bearing capacity predicted value, and making a comparison of the three kinds of value, and the code predicted value is partial to in conservative.For the beam and slab raft foundation, just considering the imitation of list across type raft foundation. And getting the fracture, the deformation, the stress as well as the distribution of foundation reaction force.Under the small load, the distribution of foundation reaction force is homogeneous, but with the increase of the load , the foundation reaction force presents as nonlinear and concentrates on rib beam and its surroundings 2.5% plate thick scope. The board and rib beam both represent the phenomenon of inverse bending. In the punching shear calculation, considering board destructive mode and node destructive mode.At last, make use of SAP2000 and ADINA finite element software to analyse the influence of punching shear behaviour of slab because of the variety of foundation stiffness as well as distributed case and evolutive state of crack of slab.