Reliability Analysis Of Falsework With Consideration Of Human Errors

With the continuous development and improvement of structural reliability theory, researchers have come to realize the importance of human errors and have found that human errors have become the main reason for the engineering accident. Regardless of human errors in the reliability calculation is imperfect method. In this paper, by the research of 16 project sites, the probability of occurrence in each main human error is statistically analyzed and arranged, and the width of second keel,wall-thickness of steel tube and bolt tightening torque are selected to conduct a field measurement and statistical analysis. By ANSYS FEM analysis, the influence of each main human error on the security of falsework is analyzed, also in the condition of human errors the influence of vertical bridging on the security of falsework is analyzed. Reliability indexβof pole stability with human errors is calculated. research results are as follows:(1) By the research of 16 project sites, high frequency of human errors are found out: Inadequate setting of bottom horizontal bar,Unsetting of vertical bridging,Unconnected between falsework and shaped structure. And the lowest frequency of human error is that Standard is set under formwork of beam, while horizontal bar which is vertically connected with the standard is not set.(2) In order to prove the high frequency of occurrence in human error at the construction site, the width of second keel and wall-thickness of steel tube in terms of materials and bolt tightening torque in terms of human operator are selected to conduct a field measurement and statistical analysis. The results show that both the width of second keel and wall-thickness of steel tube obey normal distribution, and their mean are 36.76mm and 3.08mm respectively. Bolt tightening torque obeys truncated normal distribution and its mean is 24.079 N·m.Compared with code requirement, they can not meet the specifications, which shows that human errors at the construction site are universal.(3)By ANSYS FEM analysis, the influence of each main human error on the security of falsework is analyzed, and influencing factors are calculated. Curve charts of Ultimate bearing capacity changing with main human errors are obtained. Also in the condition of human errors the influence of vertical bridging on the security of falsework is analyzed and the result show that vertical bridging has played a huge role in the erection of falsework with improving ultimate bearing capacity.(4) In accordance with the specifications, reliability indexβof pole stability with or without human errors are calculated by JC method. The result show that reliability indexβof pole stability can not meet regulatory requirements with human errors(β=2.82), but the result is in the opposite without human errors(β=3.99).