Research On Mechanism And Development Of Early Crack Of Basement

Researching work in this paper focuses on the crack control of basement. Through the theory analysis and finite analysis of the basement—soleplate, side wall and floor and so on, some useful conclusions of crack control of basement are obtained.Firstly, the performance of essential physics and mechanics of concrete is discussed and necessary condition—restraint leading to cracks of basement is studied. We utilized the reference materials in the Technical Code for Building Pile Foundation to calculate with look-up table the restraint value when pile block is joint with soleplate or foundation. Some reference conclusions are obtained through analyzing self-restraint stress of reinforced concrete member.Secondly, on the basis of the restraint value, we use the side rigidity of cantilever pile equivalent to restraint effect of pile to foundation or soleplate and we use the spring element to simulate the restraint effect of ground to soleplate. We found the finite analytic model of soleplate with spring-equivalent pile to simulate the soleplate, which is restrained by pile and ground base. We show the method of analyzing the soleplate using this model through an example. While we keep the rebar's space invariable, then we reduce or increase the rebar's area and calculate the models using the finite program. Through comparing the results, we know that it is nearly ineffective to reduce the tensile stress of concrete by increasing the reinforcement of the soleplate in elastic stage.Thirdly, we apply the theory of increment method to analyze the stress field of basement in construction period under the action of temperature and shrinkage strain by finite program ANSYS. Taking a true basement as original mold, we analyze the distribution of wall and floor of basement under the action of six load cases and obtain series of conclusions.Lastly, through analyzing the real crack distribution and crack shape of basement and comparing the real state of basement with the conclusions mentioned above, analysis indicates that the conclusions mentioned above are reasonable. We believe that reason of causing cracks of wall is effect of temperature and shrinkage strain. Then we take some measures of material, construction and design to controlling the cracks of wall. Practice proves to be effective. We bring forward conception of conceptual crack control and present the principle and method of conceptual crack...