Research On Mechanism Of Temperature Cracks And Conceptualized Anti-crack Design Method Of Masonry Structure

Masonry structure is one of the most important forms of residential buildings in China. The common and urgent to be solved problem for this kind of structures is temperature cracks. The objective of this paper is to do the observation and simulation of the temperature field and to study, the calculation method of the temperature stress of masonry structure. Furthemore, the conceptualized anti-crack design method of masonry structure based on temperature effect is discussed.A lot of studies have been done on cracks of masonry structure both in and outside China. There is no systematic research in this field up to date. Different opinions have been proposed focusing on qualitative analysis of temperature cracks. The present situation in this area can be summarized as follows: (l)There are not enough observation data on temperature field.(2)Temperature stress calculation theories are premature.(3)Furthermore, methods of controlling the temperature cracks in masonry structure are incomprehensive, including those proposals in' Masonry Structure Design Criterion '(GB50001-2001).The main work presented in this paper includes:(l)The mechanism and types of temperature cracks in masonry structure have been studied .(2) The temperature field of the wall and roof of a masonry structure has been observed.(3)The temperature field of a masonry structure has been simulated with a computer program and the results are compared with the observation data.(4)The FEM of temperature stress has been studied.(5)The distribution rule and the characteristics of temperature stress in a masonry structure have been discussed based on a real project.(6)Temperature stress in masonry structure is influenced by many factors, such as temperature, restriction degree of the structure, structural patterns and dimension, and etc.(7)The conceptualized anti-crack design method of masonry structure has been put forward based on material, constructional measures and construction techniques.On the basis of the researches mentioned above, the following important results are obtained:(l)The rule of variation of temperature field with time in wall and roof of a masonry structure have been obtained, and the result of the temperature field simulation is consistent with test data.(2)The difference of temperature along thickness in concrete roof with heat preservation layers changes less than that without heat preservation layers. (3)The places of the temperature cracks can be forecasted on the basis of the stress charts. The draught stress is bigger at the roof circumambience, the walls of the end two rooms of the top two floors, the east and west walls, and the hole corners of the doors or windows. The shear stress is larger at the interfaces of the top walls and the end interior walls. The above conclusion is consistent with the fact and the temperature cracks may emerge there (4) The temperature cracks can be effectively controlled based on the conceptualized anti-crack design method of masonry structure. The conclusions about masonry structure drawn in this paper can provide reference for design and analysis of masonry structure.