Finite Element Analysis And Experimental Study On A New Type Of Prefabricated Composite Shear Wall With Concealed Bracing

Prefabricated composite shear wall structure belongs to the German technology, it consists of two layers of prefabricated side wall, the tie lattice rebars and the composition of cast-in-situ concrete, and it is a collection of standardized design of the components, factory production and prefabricated construction of new building structure system. Prefabricated composite shear wall technology was introduced into our country in recent years, and has been or is being widely used in some areas. Prefabricated composite shear wall structure has natural junction surface defects, therefore how to ensure reliable connection of the horizontal seam between the up and down prefabricated walls and the vertical seam between adjacent walls is the key problem required to be solved before the application of this technology in earthquake zones.In addition, when prefabricated composite shear wall is applied in the high-rise building, the thicker plain concrete filling in the cavity will lead to bad stress distribution and too much weight, thus the development is inevitably limited.Based on the existing researches of predecessors, and combining with the author’s research results applying high damping concrete and concealed bracing in shear wall for many years, in order to improve the bearing capacity, reduce the thickness, and further improve the ductility of the prefabricated composite shear wall under the action of earthquake, a new prefabricated composite shear wall with concealed bracing is proposed in this paper, namely: setting left and right gap at the bottom of the wall limb, and built-in X steel concealed bracing with shear resisting reinforcing rods, then pouring self-compacting concrete into the cavity and adding local high damping materials at the bottom plastic hinge area.By using model experiment, theoretical analysis and finite element calculation, the systematic study on the new prefabricated composite shear wall with concealed bracing was carried out in this paper.The main research contents of this thesis are as follows:(1) Experimental study on one piece of local high damping concrete prefabricated composite shear wall specimen and one piece of local high damping concrete prefabricated composite shear wall specimen with concealed bracing was conducted under repeated low cycle horizontal load. Bearing capacity, hysteresis property, skeleton curves, displacement ductility, rigidity degeneration and energy dissipation capacity, were obtained and compared with each other, and compared with related prefabricated composite shear wall tests.Experimental results indicate that local high damping concrete prefabricated composite shear wall has similar failure pattern and crack distribution with local high damping concrete prefabricated composite shear wall with concealed bracing, while the latter has a more fully crack development, showing higher bearing capacity and better ductility, and interrupt of the steel concealed bracing for the tie lattice rebars can still guarantee the integrity of the composite layer and the introduction of high damping materials can improve the seismic performance of the connected interface, at the same time, the concealed bracing can guide and constrain the development of the concrete inclined cracks.(2) The ABAQUS software and the nonlinear spring element were used in this paper to simulate the mechanical behavior of old and new concrete interface at the horizontal seam, and finite element model was set up to analyze the experimental models’ nonlinear performance under monotonic horizontal load. The calculated results are in good agreement with the test results which shows that the finite element model and the selected parameters are reasonable and accurate. After the accuracy of the finite element model was verified, the effect of axial compression ratio, reinforcement ratio of the embedded column, steel ratio of the concealed bracing, and the dip angle of the concealed bracing were further analyzed in this paper.The calculated results show that the increase of the axial compression ratio can increase the bearing capacity and the stiffness, but excessive axial compression ratio is unfacourable under earthquake; the increase of the reinforcement ratio of the embedded column can obviously improve the bearing capacity;and the increase of the steel ratio of the concealed bracing can improve the peak capacity in a larger degree, but has almost no effect on the initial stiffness; reasonable dip angle of the concealed bracing can fully yield to consume more energy and improve the seismic performance.(3) Practical calculation method was proposed for the new type of prefabricated composite shear wall at last. The calculated results were compared with the test results and some finite element analysis results, which verifies the reliability of the practical calculation method. This practical calculation method can provide some reference for structural design of the new type of prefabricated composite shear wall.