Micro-model Of Masonry Structure And Test Method Of Shear Strength Of Masonry Along Horizontal Bed Joints

As the material are easily obtained and low cost, the fired clay brick has been the main material of wall.To save energy, save land,protect environment and achieve sustainable development, the reform of wall materials has been promoted by relevant state departments, so many new wall materials which are energy conservation and environment-friendly are produced. The higher demands against the old test criteria of masonry are requested by the new wall materials,then China Construction Ministry of Housing and Urban assigned a task about revised "Mechanical tests on masonry structures and standards" (GBJ129-1990). This study involved the revise of the test about the shear strength of masonry along horizontal bed joints.Try to use the micro-model verifide by experiment to analyse the impacts of different loading way, different block type and different block height on the shear strength of masonry along horizontal bed joints, and in order to proposed a more rational basis for test method.Through the basic mechanical test of autoclaved lime sand brick, shale brick and mortar, the flexural strength, compressive strength of bricks and the cube compressive strength, splitting tensile strength of motar are measured,and analyzed with the established results,then the formula for calculating the basic mechanical strength and the relationship between the strengthes are established.The experiments of prism strength of autoclaved lime sand brick, shale brick and mortar are conducted,failure modes and stress-strain are analyzed,then combined with the existing research results, the elastic modulus and Poisson's ratio formula of bricks and mortar are obtained. The interface between brick and mortar are regarded as a connection with zero thickness,to simulate the slip failure of the interface.Because of the brittle failure of double-shear specimen,elastic-brittle constitutive relation is adopted,the failure criterions of brick,mortar and interface are acquired,and the micro-model of masonry structure are established. The analytical results of the micro-model are compared with the experimental results which included 24 specimens of three blocks and 18 specimens of nine blocks,and the micro-model are proved with good accuracy.Finally, impacts of the load way,block type and block height on the shear strength of masonry along horizontal bed joints are analysed by using the micro-model considered slip, the results of analysis show that the joints of specimen are not in pure shear state , with the increase of motar's compression strength or of the block's elastic modulus, the shear strength of specimens are increased,and the growing are similar under GB or EN loading way. but the impact of block's height on shear strength can not neglect under GB loading way,and which can be neglect under EN loading way.Through analysis, the EN load method are recommend to determine the shear strength of masonry along horizontal bed joints.