Study On Cracking Mechanism Of Brick-concrete Structure Wall Based On Air Conditioning Effect

For decades,there are a large number of domestic and foreign experts and scholars for the masonry structure cracks have a very detailed scientific research.It is generally believed that the reason for the development of masonry structure crack is seasonal temperature difference,settlement and stress crack.In the past,most of the temperature cracks were used to study the direct influence of building envelope on natural temperature change and solar radiation.According to the cracking of masonry structure,the cracking reason of interior wall is different from the previous research.Therefore,this paper takes the indoor wall cracking of a commercial residential building project in shaoshan city as the research background,focuses on the analysis and research of the mechanism of the wall cracking,and obtains the following research results:(1)The paper combining with an actual brickconcrete building top wall cracking of field test results,the temperature stress of masonry structure analysis and finite element simulation analysis software,the result shows that the reasons for the formation of the cracks is different from the seasonal temperature difference and settlement and stress of masonry structure crack,puts forward the high temperature in summer season of the air conditioning effect caused by indoor and outdoor temperature difference is the main cause of the brick walling.(2)Based on the shear stress method and stiffness analysis results,it is shown that the indoor and outdoor temperature difference caused by the air conditioning effect in summer can lead to the cracking of the brick masonry.However,due to the difference of internal and external wall stiffness,the internal partition wall cracks first due to its small stiffness.(3)According to the simulation results of SAP2000 software,the temperature stress cloud diagram is consistent with the indoor wall crack distribution diagram of a commercial and residential building project in shaoshan city.The results prove that the finite element analysis can better reflect the actual situation,and the cracks in the actual project can be well simulated.If the thickness of the inner partition is changed(180mm and 240mm),the cracking strain of the partition is obviously decreased,and the cracking of the partition can be avoided.(4)According to the finite element analysis,in the same floor,the influence degree of air conditioning effect is from the southwest > to the southeast > to the northwest > to the northeast of the central >.It is suggested that the occupants near the west and south should consider the influence of air conditioning effect during the construction of indoor partition wall and increase the thickness of indoor partition wall appropriately.Finally,the cracking mechanism of the wall is obtained: the temperature difference between inside and outside the room caused by the air conditioning effect causes a large tensile stress on the external wall,and the internal partition connected with the wall(the stiffness is small and the strength is low)is cracked due to the large stiffness and high strength of the external wall,which is still caused by the temperature difference between inside and outside the room caused by the air conditioning effect.Therefore,the effect of air conditioning can not be ignored for the cracking of brick wall structure.