Reinforced Concrete Framed Tube Structures Under Seismic Action, The Space Truss System Layer Model For Nonlinear Analysis

Doctor Candidate: Yan QiwuSupervisor: Prof. Slien PLlshengIiithis thesis, a systematic theory on spatial elastic-plastic time-history Analysis of reinforced concrete frame-tube structures tinder strong multiple earthquake excitations is established. covering problems about materal,rnember and structural system considering about the nonlinearity of material,geometry and boundary.I.A Mtil(iaxial elastic-plastic hardening-sofling constitutive model of concrete is proposed iii order to offer a nonlinear material model of concrete for space restoring force analysis of reinforced concrete members taking into account the softening behavior of concrete. The concrete material model is incorporated the elastic-plastic hardening fracturing constitutive model of concrete with the plastic-fracturing theory of concrete, modified without defining two loading functiomis,and based on five parameter power function failure criterion proposed by Guo Zheng-hai etc from Tsingliua (Jniversity,or three parameter unified strength theory proposed by Yu Mao-hong from X iAn iiaotong University.2.A sectional cross-sectional discrete yield-surface model is proposed to found a foundation of theory for the spatial nonlinear analysis of reinforced concrete members. The method is based on the mnultiaxial elastic-plastic hardening-softening constitutive model of concrete, adopted* the yield surface theory, and the substructure technique.3.A space bond slip relation of reinforcements in either end of a member is proposed, based on one-dimensional bond slip model of reinforcements proposed by Teng Zhiniirmg from Tsinghua University , the first-time loaded ascending stage抯 curve of which model is modified as the line which parameters are not changed so as to simply the computation. The bond, slip is regarded as the boundary nonlinearity of a member. Consideration of the additional axial, two angular deformations generated by the bond slipping in anchorage zones of joints,the assumption is made,that the plane section of either end of a member before bond slipping of reinforcements remains afler bond slipping of reinforcements. Additional deformations* Contribution to stif抐nesses of plastic sub-elements is formed from the boundary nonlinearity of plastic stabelements. The space bond slip relation can truly compute bond slip in anchorage zones, additional def抩rmatinns,and their contribution to the space nonlinearity of a niember,has used iii space nonlinear analysis of columns and spandrel beams in this dissertation.4.Because there are sub-elements in a member with the introduction of inner joints, when tile spatial stifmess matrix of main joints of a member is made,there are some cases of solving the double nonlinear equations,negative stifmesses,and singular stiffness matrices in process of iterating. An inner iterative incremental displcacement procedure on the basis of the harmonization of the deformation amid the displacement function,and an inner iterative incremental load procedure cmi the basis of tile dispacement function and the improved arc-length method are proposed. The computation of examples shows that there is good stability in algorithm for both themethods.S.Consideration of interaction on the nonlinearity about the material,the geometry,and the boundary of the columns subject to axial force.biaxial hending,and torsion,an analytical model of hysteretic curve of columns is presented,based on the sectional cross-sectional discrete yieldsurface inodel,the bond slip in anchorage zones regarded as the boundary nonlinearity of a memher.and the iterative procedure of displacement of inner nodes on the basis of the hamonization of displacement.6.The sectional cross-sectional discrete yield-sruface model is used to spandrel deep beams, the effect of the shear deformation to shear force on (he m~terial nonlinearity is considered, (he bond slip in anchorage zones is regarded as the houndaty nonlinearity of a member. Except the geometric nonhineaicty. consideration of double nonlinearities ab...