| Steel-concrete composite beam is a kind of beams which connect the steel beams and concrete slabs by shear connectors to co force and deformation compatibility. The composite beam can make full use both the superior tensile properties of the steel and the superior compression resistance capability of the concrete, and improve the stiffness and stability of the beam significantly. However, there will be disadvantages for concrete stress and steel compression in the negative moment area of the continuous composite beam. Resulting in section stiffness decreasing of the beams in negative moment area and cracking easily of the concrete slabs, influencing normal using function. The current crack formulas are calculated under the hypothesis that the composite beams combined completely. By studying on the influence factors of crack, the thesis analyzed the crack width in negative moment area after considering the shear slip influence on the connecting face of the composite beam.Calculated the steel stress that before and after the composite beam cracking by analyzing the strain difference on the connecting face, got the crack width of the concrete slabs. Verified the validity of steel stress by test data of three test beams.Finally, simulated the changing situation of the steel stress and the crack in negative moment area of the composite beam and analyzed the area systematically by the software ANSYS, verified the correctness by test. |
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