The Study Of Bending Property Of Trapezoidal Cross-sectional Flexural Member

Foundation design is an important part of building structure project,reasonable foundation design can not only provide security assurance for the upper structure,but also save the project cost and shorten the construction period.There are some ambiguities in the current code for foundation on reinforcement calculation of reinforced concrete independent foundation.This paper provokes thinking mainly from the reinforcement calculation of independent foundation,and then study bending properties of the trapezoidal cross section beam after the independent foundation simplified to trapezoidal cross-sectional beam.In the actual projects,it is needed to adopt the trapezoidal cross-sectional beam sometimes,but the calculation formula for bearing capacity of trapezoidal cross-sectional beam has not been given in the <code for concrete structure design >.The designers all calculate approximatively according to the basic theory and making some assumption.Some of these results are conservative,and some are unsafe.With the trapezoidal(rectangular)cross-sectional reinforced concrete beam of the same cross-sectional area and height but different side angles(corner)as the research object,this paper studies the flexural bearing capacity and the relationship between the bending bearing capacity and the change of cross-sectional shape,the main contents are as follows:(1)The load test is carried out through designing three groups of trapezoidal(rectangular)cross-sectional reinforced concrete beam of the same cross-sectional area and height but different side angles(corner),comparing and analyzing the test results,and the relationship between the bearing capacity of trapezoidal cross-sectional beam and cross-sectional angle is concluded.(2)Through analyzing the bearing capacity of each group of reinforced concrete beams and the strain of rebar and concrete in the different places in the loading process,the phenomenon is concluded which the strain of the trapezoidal cross-sectional beams is different from that of the rectangular cross-sectional beam,and there is strain hysteresis in some places.(3)Numerical simulation of the static load test is carried out through establishing finite element model of trapezoidal(rectangular)cross-sectional reinforced concrete beam,and the conclusion that the numerical simulation results are close to the experimental results is drawn.Under this premise,the bearing properties of trapezoidal cross-sectional beam with 30-degree cross-sectional angle are simulated and studied.(4)According to the experimental and theoretical analysis,the calculation formula of flexural capacity of the concrete flexural member is presented.(5)With the formula deduced in this paper,the engineering example of the independent foundation is calculated,and compared with the results calculated by the traditional method.