Research On Bending Stiffness And Crack Of Simply-Supported Beam Of Iron Tailing Concrete

In this paper, in order to study the stiffness formula and the crack formula of ordinary concrete beam is applied to tailings concrete beams-15 tailng sand concrete beams and three ordinary concrete beams were tested under bending loads, the test phenomena and test data are analyzed theoretically.The main conlutions and achievements of this thesis are as followings;(1) Longitudinal tensile reinforcement strain characteristics of tailng sand concrete beams are the same as that of ordinary concrete beam tailings concrete beams. They all can meet the plane assumption. When the concrete strength grade and longitudinal steel reinforcement ratio offeree are the same, under the same load of normal use, tailings concrete beam longii-tudinal reinforcement strain is slightly larger than that of ordinary concrete beams.(2) Tailng sand concrete beam deflection curve also divided into three stages: approximate pre-cracking, cracks occuring to steel yielding and steel yielding to failure. When concrete strength grade is the same as that reinforcement ratio of longitudinal reinforcement, under the same load of normal use, the midspan deflection of tailings sand concrete beams is slightly larger than that of ordinary concrete beam.(3) To tailings sand concrete beams,the section resistance moment coefficient,inner arm coefficient, cracks uneven coefficient are carried out based on linear regression. Then the short-term stiffness formula of tailings sand concrete beams was obtained under normal load conditions. Comparing it with the normal concrete,it is showing that the stiffness of tailings sand concrete beams is slightly lower with 1.1% than that of normal concrete, which reduces the amount of about 1.1%. As the reduction amount of stiffness is small and can be ignored, the short-term stiffness formula of normal concrete beams can apply to the short-term stiffness formula of tailings sand concrete beams.(4) Based on linear regression formula of tested data of the maximum width formula of tailings sand concrete beams. The calculate crack width is 16% larger of than colulating maximum width ccording to the formula of concrete specification. The results is showing that, the proposed width calculation formula is better, and more suitable to calculating the maximum crack width of tailings concrete beam maximum crack width.