Research And Application Of Equivalent Truss Model On Nonlinear Finite Element

Equivalent truss element, the combination of a group of discrete hinge link, is anew finite element model between the traditional limited continuous uint and thefinite discrete element. The birth of equivalent truss element has pioneered a newfinite element analysis method for reinforced concrete assessment. Using equivalenttruss element in the finite element analysis of reinforced concrete means more concisedefinition of material constitution and more simple for processing material crackingdamage. Meantime, Computational efficiency and convergence has been greatlyimproved.Plane equivalent truss element is combined of six hinge link elements. In roder tofully reflect the complex non-linear mechanical properties of concrete materials, it isnecessary to systematically discuss and analyze cross-sectional area of each link, theconstitutive relation of materials and also failure criteria in the plane equivalent trusselement. Based on previous studies, according to the requirements of engineering, thisthesis has proposed three planar truss nonlinear computational model.First, cross-sectional area of each link and the constitutive relation of materialsin the plane equivalent truss element were derived from principles of stiffness andstrength equivalence.Then the destructive conditions of each rod in the planeequivalent truss element and treatment method were difined by equivalence principleof failure criteria.Later, the accuracy and application of the calculation model in the three planarequivalent truss were discussed through mechanical properties analysis of the plane ofthe equivalent truss element.Finally, in order to imitate the occurrence and development of crack morerealistically, the randomness in failure criteria of materials was considered in theplane of the equivalent truss element.Based on the theoretical model above, this thesis has written related programwith secondary development of ANSYS technology. In this program, we have takenthe combination of the plane equivalent truss element with the square planar unit orreinforced unit into account. At last, under different shear span ratios, we havecompleted mechanical performance analysis of a group of simply supported beamswithout web reinforcement. With more reliable calculation results, we have drawed the corresponding diagram of crack development.