Research On Shearing Capacity Of Concrete Beam Reinforced With Rectangular Spiral Stirrup

Configuring rectangular spiral stirrup in the concrete beams can not only save a lot of man-hours and stirrups, can also improve the integrity and bearing capacity of concrete structures, rectangular spiral stirrup has a good contribution to stiffness of reinforcement skeleton. Now the mechanism and effect of rectangular spiral stirrup in concrete beams are not fully understood, research for shear bearing capacity of concrete beams configuring rectangular spiral stirrup is less at home and abroad. The lack of research limits the application of concrete beams configuring the rectangular spiral stirrups in engineering. It is necessary to study the rectangular spiral stirrups concrete beams.The paper studies the effect of shear strength of the rectangular spiral stirrups concrete beams under monotonic concentrated load. Factors affecting the inclined section bearing capacity of concrete beams are many, this paper mainly studies the strength grade of concrete, the stirrup ratio, shear span ratio, stirrups’ winding form. Stirrups arranged along the length of beam are distributed into the symmetric arrangement and anti-symmetric arrangement. Each factor for each arrangement uses three levels, according to the orthogonal experiment L9(34) determines the number of specimens, this paper studies and makes 20 test beams, which contains 2 beams reinforced with common form of rectangular stirrups, 9 beams along the length of beam configured in the form of symmetric rectangular spiral stirrup, and 9 beams along the length of beam configured in the form of anti-symmetric rectangular spiral stirrup.The experiment measures the steel bar’s strain, concrete strain, crack width, support displacement and cross-displacement. It describes in detail emergence and development of diagonal cracks of test beams, the process of destruction of each test beam under loads, analyzes shear-- deflection curves and shear-- stirrup strain curves of test beams, analyzes longitudinal reinforcement strain, concrete strain and shear bearing capacity of symmetric and anti-symmetric rectangular spiral stirrup concrete beams. The results show that, the concrete beams configuring rectangular spiral stirrups are conducive to the shear bearing capacity of inclined section, Trilateral and quadrilateral winding form of rectangular spiral stirrups also improve shear bearing capacity of the beam. In addition, this paper also analyzes the extent of influence of strength grade of concrete, the stirrup ratio, shear span ratio, stirrups’ winding form, the shear span ratio affects the most significant.This paper is on the basis of the analysis of test data, according to the form of calculation formula of shear bearing capacity of inclined section in Chinese code、the United States code and Europe code, based on the truss model, uses MATLAB software fitting out the calculation formula of shearing bearing capacity of configuring rectangular spiral stirrup in the concrete beams. Compared calculated value with measured value of shear bearing capacity, matching degree is very well, it can be used as a reference to further research and engineering practice.