Research On The Basic Mechanical Properties Of Block Stone Masonry

Block stone buildings are still wildly used in South-east of China. These buildings may suffer great. According to the characteristics of the region’s block stone buildings, this paper presents the test of compressive and shears bearing capacity. Combing with mechanical analysis and finite element analysis, they together provide guides for the buildings by comparing their results.In this paper, seven groups (totally 21) specimens were tested to investigate the failure progress under compression, the effects of mortar strength and mortar joints thickness on the compressive behavior of block stone masonry. It turned out that their failure could be divided into three phases:elastic stage, cracking stage and destruction stage. It is brittle failure; meanwhile rough block stone masonry’s is more obvious than smooth block stone masonry’s. It has pretty high bearing capacity. Mortar strength is effective to it and mortar joints thickness is less effective to it. And smooth block stone masonry’s discrete nature is smaller than rough block stone masonry’s. Mechanical analysis turned out that:block stone is in tension while masonry is in compression in the horizontal in axial pressure because of the difference of their prosperity. Their horizontal forces are mainly affected by mortar strength, the ratio of block stone’s thickness and mortar joints’. And on the basis, a new formula for both rough and smooth block stone masonry’s compressive strength is proposed. The formula take mortar’s strength, block stone’s strength and the ratio into apart, reflect the relationship between compressive strength and masonry’s horizontal force. It can be consulted when amending the codes. Finite element analysis gets their stress clouds, which show that stress concentrations are obvious near the nodes of vertical joint and up/down stone, where cracks appear firstly. The sizes, direction, factors of block stones and mortar’s horizontal forces are almost same with the results of mechanical analysis.Six groups (totally 18) specimens were tested in this paper. Cohesion and friction are gained directly by hydraulic servo-system (MTS). The tests turned out that:when the specimens are shear friction damaged, their failure could be divided into three phases, namely elastic stage, adhesion disappearing stage and friction energy consuming stage; mortar strength is effective to cohesion while normal stress is effective to friction. Standard value and design value of shear capacity are proposed by taking the difference of cohesion and friction’s discrete nature. Combining the results of test, mechanical analysis and finite element analysis, we can get a conclusion:with the increase of axial compression ratio, the damage occurs at the level of the unit-mortar interface, mortar, block stone, which represent the shear friction, shear compression and baroclinic damage. Mechanical analysis gets the three principle stress and their direction of specimen under shear-compression and their change. On the basis a new theory about shear-compression correlation curve, namely vary-cohesion, is proposed, which make the curve smooth at the joint of shear friction and shear compression damage. Mathematic demonstrates it in this paper. The stress clouds of mortar and block stones are gained through finite element analysis, when axial compression ratio is increasing, are gained. It demonstrated by comparing with the results of mechanical analysis.