Temperature Stress And Its Finite Element Analysis Of Large Area Concrete

With the development of economic and society, extremely long or wide buildings continue emerging. In view of the requirement of such buildings in structural integrity and functions, most of them have less expansion joints or even have no, thus forming large area concrete structures. The vital problem of large area concrete structure is crack, this is mainly because of the internal stress of concrete. Our specification requires a method of setting expansion joint to solve the problem of internal stress, but for the kind of large area concrete structure without expansion joints, research is still lacking. At present, this kind of concrete structure mainly depends on experience in designing and constructing, relevant theory is still lacking. Internal stress of concrete is biased in favor of qualitative analysis, quantitative survey and calculation is still lacking. Therefore, this topic is of great practical significance in engineering.This study was based on the underground garage project of Long-wan district in Taiyuan(transverse project: Study on Setting Method of Large Area basement; project number: 9002-030011259), through the method of consulting literature, laboratory test, field test, computer software analysis etc. to study the temperature stress and expansion joint setting spacing of large area concrete, a series of methods to prevent cracks in large area concrete were put forward. The main contents include the following aspects:1 Laboratory and field test researchThe mechanical properties of concrete were tested in laboratory test, including splitting tensile test, axial compressive test and modulus of elasticity test. Field test include temperature test and strain test. Concrete temperature stress was calculated by appropriate method, and the change rule of temperature stress was analyzed, at the same time, reasons for the change were explored. Results show that the splitting tensile strength, axial compressive strength and elastic modulus of concrete increase with the increase of concrete age.2 Finite element analysisBy the finite element software ABAQUS, the strain and temperature stress of concrete floor and roof were analyzed, and the stress and strain results were compared with the calculated ones to verify the feasibility of calculating temperature stress by finite element software. Results show that the change rule of strain and temperature stress of two different methods were approximate, but the strain were less than the measured value.3 Approximate calculation of expansion joint set spacingCalculated expansion joints set spacing of concrete through approximate calculation formula and the measured strain in filed test and the calculated temperature stress. Results show that the approximation algorithm of the expansion joints set spacing is conservative.4 Propose measures to prevent cracks in large area concreteComprehensive two different methods to obtain the temperature stress, a series of measures to prevent cracks in large area concrete were proposed. Include design control, material control, construction control, etc.