Research On Mechanical Properties Of The Prestressed Masonry With Seams In The Constructional Columns

The post-tensioned method is adopted to construct the unbounded prestressing reinforcement arranged in the constructional columns of masonry structure,and the technical measures are adopted in the structural columns to set the horizontal seams.The cohesive force between the wall and the structure columns,the uniform compressive pre-stress applied in the wall by each floor ring beams,self-resetting performance of prestressed masonry,and the weakly frame behavior strengthened by ring beams and structure columns are used to improve the shear capacity and deformation capacity of the masonry,then its energy consumption and ductility are corresponding improved.Until now,there are few researches on the mechanical properties of prestressed masonry under various prestress sizes,and the distribution law and mechanism of prestress acts on the wall are not clear.This paper concentrates on the problem of shear performance of prestressed masonry,distribution of prestress in masonry,calculation of prestressing loss,calculation of shear capacity and some issues in the construction of prestressed masonry,The research method used in this paper is numerical simulation analysis by means of ABAQUS,the main research content is as follows:(1)This paper established a separated finite element model using ABAQUS which can reflect the viscosity and friction of the interfaces and describes the constitutive relation and functional principles between the interfaces.In order to ensure the rationality of the model,shear strength test of three combined bricks and a piece of wall are simulated.The results reflects the relationship of shear and compressive of the bricks and describes cracking pattern and failure characteristics successfully.(2)The test of the seismic performance of prestressed masonry and non-prestressed masonry was simulated by using the finite element model established above.Comparing the test results and the simulation results,distribution of the stress-strain,damage of the materials and stiffness degradation of specimens were analyzed and expounded the distinction of the bearing capacity,deformation mode,cracking failure process and seismic behavior between the prestressed and non-prestressed masonry and the mechanism of prestressed reinforcement improving the seismic behavior of masonry.(3)Two finite element models of prestressed masonry with aspect ratio of 0.5 and 2.0 were established and prestressing force of 0.1mf,0.2mf,0.3mf were applied to them.The seams were set in different positions of columns and its influence on the distribution of prestress of the wall were analyzed.The effects of different distributed prestress on the mechanical behavior of masonry were also analyzed from the aspects of the distribution law of strain,the damage evolution and the stiffness degradation.(4)The reasonable range of pre-stress was proposed.The calculation method of control stress for prestressing,prestressing loss and the area of prestressed reinforcements of centralized prestressed masonry were established.Some constructive measures and the calculation formula of shear capacity of prestressed masonry considering the influence of compressive pre-stress,constructional column and masonry were put forward.