Abstract:To study the force characteristics of the connection components of the large cantilever continuous box girder widening bridge,taking the Nügukou Bridge reconstruction project as the research background,fine numerical simulations of the entire bridge and local sections are conducted with finite element software Midas Civil and Abaqus.The stress conditions of the overall model of the widening bridge under three working conditions:partial load,constant load combination,and operational state are analyzed,along with the changes in bending moments before and after widening the bridge.The stress on the local component model is analyzed under operational conditions.Strain monitoring is performed on the box girder and transverse ribs,and a comparative analysis of the measured stresses and the stresses obtained from the finite element model is conducted.The operational state is the most unfavorable condition,under which the stress extremes of the left and right box girders are located in the middle regions of the 2nd and 15th spans.A local refined model is established for the 15th span,which exhibits the maximum stress and vertical displacement.After loading,the stresses on the transverse ribs,mortises,and stirrups are analyzed under the operational state.The compressive stresses of the transverse ribs in the longitudinal and transverse directions exhibit a symmetric distribution,with longitudinal stresses decreasing from the ends toward the middle region.The maximum compressive stress at the ends is-5.40 MPa,and the maximum tensile stress is 0.42 MPa.The transverse compressive stresses decrease from the middle to the ends,with the maximum compressive stress in the middle being-5.50 MPa and the maximum tensile stress being 0.39 MPa.Under the operational state,the extreme values of stress for the reinforcement in the mortise connections appear in the middle region near the side walls of the transverse ribs,with the 5#mortise bearing the maximum stress of 21.56 MPa.The stirrup stresses exhibit a symmetric distribution,with extreme stresses occurring in the middle regions of the vertical reinforcements on both sides.The 4#stirrup bears the maximum stress of 71.43 MPa,while the 10#stirrup bears the minimum stress of 35.65 MPa.The overall stiffness of the bridge structure increases after widening,with changes in the load transfer path.The bending moment distribution of the original main beam under operational conditions is significantly altered,with the maximum bending moment in the positive moment region generally decreasing,while the absolute value of the maximum bending moment in the negative moment region slightly increases.The measured longitudinal stresses of the top and bottom plates of the left box girder in the 15th span are close to those of the finite element model,while the measured stresses on the bottom surface of the transverse ribs differ significantly from the finite element model stresses at L/4,L/2,and 3L/4.

Abstract:In order to make a quantitative study of the operation flow of warehousing system , the method of combining the traditional ECRS principle with the “5W1H” question is improved as the one of combining the ECRS principle with the dynamic programming algorithm .By taking the storage system of a logistics enterprise as the research object , the model of warehousing flow is established by using the Flexsim software , and then the blocking process and resource utilization in the operation flow are optimized .The results show that the optimization method of warehousing flow based on the ECRS principle and dynamic programming is easily used to design the flow optimization , which can help the administrator determine the improved process quickly and accurately .Compared with the warehousing flow before the optimization ,the average utilization rate of equipment after the optimization increases by 18.64%,the average blocking rate decreases by 72.28%,and the operation flow and resource distribution are simplified .The research results can provide a theoretical basis for optimizing the production flow of enterprises .