Current Issue : January-March Volume : 2023 Issue Number : 1 Articles : 5 Articles
In order to solve the problem of 3D modeling in building assembly, an application of a 3D model based on the real scene in the building assembly structure is proposed. This method, based on the current BIM technology in nanomaterial design research, analyzes the problems existing in the traditional assembly structure design scheme and analyzes the feasibility of BIM technology in the forward design of assembly buildings from the perspective of theory and practical application. The experimental results show that the urban building model established by the 3D model has high precision and a good real-scene effect. The accuracy of the building model meets the requirements of 1 :1000 mapping, has measurable accuracy, and elevation accuracy is better than 30 cm. The 3D model promotes the development of informatization....
In order to solve the problem of steel bar desensitization in island concrete, which leads to steel bar corrosion and greatly reduces the service life of structures, this work studies the influence of electrochemical corrosion prevention technology on the structure and performance of concrete. Through linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS), the reinforcement in seawater sand concrete and ordinary concrete under two different chloride ion erosion modes was tested electrochemically, and then, its polarization curve and electrochemical impedance spectrum were obtained and analyzed. The experimental results show that the slope ratio of anode Tafel decreases significantly under the condition of steel bar passivation. The self-corrosion potential of reinforcement is −204 MV, which is much higher than −480MV obtained from early testing. The self-corrosion potential obtained from the L3 polarization test tends to be stable after 84 days. As the test continues, the capacitive reactance arc in L1 and L2 medium-frequency region will gradually disappear with the continuous development of corrosion. Conclusion. This study explains the electrochemical mechanism and rate of reinforcement corrosion in seawater and sea sand concrete....
An inerter system can amplify the deformation of its internal energy dissipation device, thereby improving the efficiency of energy dissipation and shock absorption. This is the so-called damping enhancement mechanism, one of the key mechanisms of the inerter system. Although the theoretical framework for damping enhancement of inerter systems has been established, the implementation of this principle for the design of an inerter system requires solving a complicated constrained optimization problem, which is not easy to be figured out using traditional approaches. To obtain valid design results through a lucid and robust method, it is proposed to optimize the damping parameters through a metaheuristic algorithm named harmony search algorithm in order to maximize the damping enhancement degree of the inerter system with the satisfaction of structural performance. First, the closed-form seismic response solutions of a single-degree-of-freedom (SDOF) structure with an inerter system are derived based on the theory of random vibration. Then, the mathematical expression of the constrained optimization problem is established. Due to the inefficiency of the original harmony search algorithm to solve the constrained optimization problem, the algorithm is modified by introducing a new harmony generating method and an adaptive strategy for parameter adjustment. The modified harmony search algorithm is compiled to solve the optimal design problem of the inerter system. The algorithm is verified by designing a structure with an inerter system. It is found that the number of iterations and time consumption until convergence required by the modified harmony search algorithm can be reduced by about 20%90% compared with the original algorithm, which confirms the effectiveness of the modified algorithm. The results of dynamic analyses show that the structure have achieved the preset performance demands under different cases and the damping enhancement characteristic of the inerter system is fully utilized....
The cable lifting construction method is the most widely used construction method for large-span arch bridges. The correct calculation and analysis of cable lifting construction is essential to ensure the safety and linearity in the construction of arch bridges. The existing research mainly focuses on the construction scheme and finite element analysis of cable lifting for large-span arch bridges. There is relatively little research on calculation theory, and there is no analytical method for cable lifting construction of arch bridges. To calculate and analyze cable lifting construction more quickly and accurately, based on the deformation coordination principle and suspension cable theory, a practical calculation method is proposed to calculate the load of the tower acting by a cable system in the cable lifting construction of arch bridges. A large-span arch bridge under construction was used as a case study, and the correctness of the calculation method was verified by measuring the displacements of the tower top. A brief description of the structure, verification method, and verification process is presented. The displacement results are calculated by the numerical calculation software SAP2000, the actual measured displacement data are discussed and comparatively analyzed, and the correctness and calculation accuracy of the proposed calculation method are also evaluated. The results show that the calculation method has sufficient accuracy. The tower load calculation is mainly undertaken to prepare for the analysis of the tower mechanical properties; therefore, the calculation method is applied to towers of the case engineering, and the stability, load carrying capacity, and deformation of the tower are analyzed to verify whether its mechanical properties meet the engineering requirements. The results show that steel pipe columns of the buckle tower are prone to twisting instability. The normal stress of the tower’s part of the pressurized rod or pressurized bending rod is larger. Wind cable load calculation models and tower design-related recommendations are presented in this tower analysis. The tower load calculation method and tower mechanics analysis method in this study can provide guidance for the calculation and analysis of the cable lifting construction of large-span arch bridges....
The design of shed-tunnel structure in the confined environment can help to avoid the safety of passing vehicles and pedestrians from being threatened by the impact of upper rockfall in highway, railway, and other rockfall disaster protection engineering. Due to the limitation of the space environment, it is necessary to optimize the shed-tunnel structure to provide enough space for passing vehicles and pedestrians. In this study, a case study was made on the passing shed tunnel of Badong Juebitianhe Revolutionary Education Base. First, the theoretical calculation of rockfall impact force was compared and optimized. Then, the optimization scheme of “column + anchor bolt + buffer layer” was proposed based on the commonly used shed-tunnel form and was verified by ABAQUS numerical simulation. The performance of the optimized shed-tunnel structure is greatly improved in terms of the space utilization rate of shed tunnel and the impact resistance of rockfall....
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