Effects Of Envelope Insulation On Temperature Action Of Masonry Buildings And Control Measures Of Wall Cracks

Volume deformation difference between top wall and roof in masonry structure lead to stress in the wall, which caused wall cracks when stress exceed the breaking strength of the wall, as the result, it reduce the normal use of the structure. Cracks are caused by the effect of temperature and drying shrinkage of masonry wall.Firstly, based on series of fourier, the indoor and outdoor air synthetic temperature simplified steady temperature field and the effect of non-steady harmonic heat temperature field which take consider of area, orientation, color, insulation form and other factors. The heat transfer differential equation was solved by variable separation to reach the analytical solution of quasi-steady temperature field.Secondly, The largest temperature load of the top wall can be got through using the harmonic method calculate the wall temperature load and the daily temperature load, then consider t masonry drying shrinkage equivalent temperature difference.Thirdly, solve the stress of top wall by use of bent analogy method and finite element method to get the distribution of shear stress in the wall.Bent analogy method calculation results, shear of the wall by the middle wall between windows to the outer end of the wall into an incremental rule.The calculation result of finite.element analysis show that the second largest wall shear and the wall under axial pressure in addition to the outer end of the outer wall limb Deduced simplified formula of temperature stress on the top wall of masonry buildings by use of mathematical regression for stress. Then, comparison of the two methods of calculating, the finite element method higher accuracy calculate the magnitude and distribution of stress.Finally, by use of simplified formula of temperature stress and Shear strength formula of masonry structure, which calculated the maximum expansion joint spacing and calculated the minimum reinforcement ratio at different conditions of the top wall, otherwise, set structural columns in the wall. Accordingly, proposed a "put" and "anti" crack control measures.