A comprehensive method for quantitatively appraising the safety rating of masonry structure is proposed which is able to reflect the difference in the same safety level. The analytic hierarchy process (AHP), fuzzy theory, and the grey clustering theory were applied based on the fuzzy-grey characteristics and the structural safety factors of the building system. A four-layer safety evaluation model of masonry structure considering its structural features was established by using AHP method and a three-level fuzzy comprehensive evaluation model was elaborated. Then, the weight coefficient vector of each layer was calculated according to the expert experience and existing research results. Based on the grey clustering method and the fuzzy evaluation model, the evaluation matrix of every layer was established. Finally, this method was applied to a practical masonry structure. Not only the result was in agreement with the appraisal result according to Chinese standard method, but also it quantitatively evaluates the safety grade of every factor in every layer.
In this paper, in order to investigate the shear mechanism and shear capacity of framework joints of steel-reinforced concrete-filled circular steel tube (SRCFCST), a numerical finite element model reflecting the mechanical behavior of framework joints of SRCFCST column-reinforced concrete beam is established through simulating concrete by the damage plastic constitutive model and simulating steel by the ideal elastic-plastic material, and its effectiveness is verified by experimental data. On account of uniform distribution of circular steel reinforced around the section and without definite flange and web, the shear mechanism of the framework joints of SRCFCST is analyzed on the basis of equivalent circular steel tube (CST) to the rectangular steel tube. The method for calculating the superposed shear bearing capacities of the joint core area is proposed, which is composed of four parts, i.e., concrete inside tube, concrete outside tube, hooping and steel-reinforced web; and the corresponding formulas for calculating shear bearing capacity are established. The comparative analysis of joints’ shear bearing capacity indicates that the results of numerical simulation and shear bearing capacity formulas coincide well with the experimental values, which can provide reference for the nonlinear analysis and engineering design of similar joints.
Based on the elastic analysis, the existing methods of the importance assessment of structural members can only reflect the structural elastic behavior. To understand the plasticity and stiffness degradation of the structure, the present study proposes a member importance assessment method which takes the structural elastic-plastic strain energy or the generalized elastic-plastic strain energy as the performance parameter. First, the existing methods of member importance assessment are explained. Second, by pushover analysis, structural elastic-plastic strain energy is calculated in accordance with the story force-displacement curve, and structural generalized elastic-plastic strain energy is calculated according to the base shear-top displacement curve. Third, the importance of structural members is measured with its effect on the elastic-plastic strain energy or generalized elastic-plastic strain energy of the structure. Given the difference between structural performance parameters, the coefficient of member importance is defined. Finally, the importance of the masonry structure wall is quantitatively assessed using the elastic-plastic strain energy method, the generalized elastic-plastic strain energy method, the generalized stiffness method, and the ultimate bearing capacity method. Besides, the effect of the seismic fortification intensity and the number of structural stories on the wall importance assessment results is analyzed. According to the results, the elastic-plastic strain energy method and the generalized elastic-plastic strain energy method can both reveal the mechanical performance of elastic-plastic state of the structure under severe earthquake. Furthermore, the greater the seismic fortification intensity is, the more important the wall will be on the bottom floor, the more the total number of structural stories will be, and the more important the opening wall and its adjacent wall will be.
Summary The life‐cycle cost‐oriented design philosophy is a promising tool for building resilient cities as it helps in gaining insights into the impact of hazard‐induced damage and repair of civil and infrastructure systems. In this study, a socioeconomic parameter‐independent practical formulation was introduced for life‐cycle cost analysis by combining the economic loss rate associated with different damage limit states and cloud analysis‐based probabilistic seismic demand model. A framework for life‐cycle cost analysis‐based seismic design optimization was proposed using an emerging nature‐inspired algorithm, namely, the multiobjective cuckoo search. By considering an eight‐story prototype composite frame, the framework was used to determine the trade‐off design alternatives between competing optimization objectives. Conventional and improved fiber models were developed to comparatively evaluate the influence of the slab spatial composite effect on Pareto optimal designs. The key drivers of change in three cost indicators were identified using generalized linear models. The result indicates that the overstrength factor is the critical design parameter affecting the initial construction, seismic damage, and life‐cycle costs, with statistical significance at the 0.001 level.
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