Research On The Temperature Cracks Of Masonry Buildings

In this dissertation, the comparison between the measures against temperature cracks of foreign codes and the measures of the Code for Design of Masonry Structures in China are made. Then the limitation of the latter is presented. The cracks of buildings are classified in detail. On this basis, the principals of temperature crack control of the masonry buildings are analyzed. Based on a wide variety of methods used for computing the temperature stress, the nonlinear finite element method is adopted. Through analyzing different models of a masonry building, the following conclusions can be made: On the influence of temperature stress, the horizontal shear stress is maximal on the wall of end bay of the top story; The splay cracks are produced on the aperture of end bay of the top story; The interlayer displacement of end bay of the top story is maximal. The factors influencing temperature cracks are temperature difference, the ratio of aperture, the installation of tectonic columns, and the longitudinal length of the entire masonry building. Accompanying the rising of temperature difference, the expansion of longitudinal length of the entire masonry building, the augmentation of aperture ratio, and the horizontal shear stress on the end wall of the top story is increased, the cracks become broader, longer and their number is added. Installing the tectonic columns can decrease the horizontal displacement of walls and enhance their resistance to crack. The resistance of outer longitudinal walls to crack is enhanced when they are bearing walls, because the vertical compression stress acted on cross-sections of walls increases their resistance to shear. The rigid roofing can lead to larger temperature stress and more serious crack of walls than the flexible roofing.Through surveying the temperature cracks of a masonry building, the walls are enhanced by grouting method, repairing the insulating layer of roofing, and strengthening the walls with steel bars. At last, the effective tectonic measures are come up with to prevent the temperature cracks.