• Current Issue
  • INCREMENTAL DYNAMIC ANALYSIS OF COUPLED TALL REINFORCED CONCRETE WALLS SUBJECTED TO FAR-FIELD AND NEAR-FIELD EARTHQUAKES

    Near-field (NF) earthquakes, compared to far-field (FF) ones, may result in a variety of responses of the structure. In this research, the behavior of a tall building with coupled reinforced concrete (RC) core-wall, is investigated. Firstly, the structure is designed using the methods in the conventional codes and utilizing the response spectrum analysis procedure. Then, fiber elements and nonlinear shear hinge are used for preparing the nonlinear model of RC shear wall and for coupling beams, respectively. The structure is analyzed using the nonlinear time history analysis at maximum considered earthquake level, implemented for NF and FF record sets and the results are compared. Results show that the base moment demand are identical and the average base shear demand obtained from the NF record is 1.5 times the corresponding demand obtained from the FF record. Also, the inter-story drift ratio demand envelope, curvature, roof drift and stories acceleration are compared. In addition, some important earthquake intensity indices for sets of NF and FF ground motions are studied. Besides, incremental dynamic analysis is used to calculate fragility curves. This analysis demonstrates that the difference between fragility curves from NF and FF earthquakes is significant. Also, with the increase of selected performance limit state, the general difference between the two fragility curves becomes relatively smaller.

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  • Current Issue
  • A STUDY ON MITIGATION OF INTERSTORY DRIFT CONCENTRATIONS IN REINFORCED CONCRETE FRAMES UNDER EARTHQUAKE DEMANDS

    Site observations and analytical studies show that low-rise RC frames have larger interstory drift ratios at the lower stories under earthquake loading. It is obvious that due to the localization of drifts, these structures could reach their capacity limits earlier than a system with a well-distributed drift among its stories. This phenomenon is especially vital for frames with limited drift capacity and could cause them to fail below the specified design demands. The existing stock of seismically deficient RC frames in Turkey, and for that matter all over the world, are in this group. The presented study investigates the effects of a pre-organized stiffness distribution along the building height to mitigate the interstory drift concentrations. As a case study, the readily available infill walls were used for stiffness-modifying elements to obtain the organized stiffness distribution. Initially, the numerical model was calibrated and verified using the experimental results. Afterward, three planar frames were studied. These were a bare frame and two frames with infill walls. Nonlinear dynamic time-history and pushover analyses were performed to evaluate the seismic performance of the frames. The results indicate that the organized stiffness distribution could mitigate the interstory drift concentrations and provide a better distribution of interstory drift ratios along the height of the frames.

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  • Current Issue
  • INFLUENCE OF TRANSVSERSE BEAMS ON THE ULTIMATE BEHAVIOUR OF SEISMIC RESISTANT PARTIAL STRENGTH BEAM-TO-COLUMN JOINTS

    The most of existing numerical and experimental studies on seismic resistant steel beam-to-column joints were carried out on planar assemblies, thus disregarding the presence of transverse beams that typically resist gravity loads in multistorey buildings. In this article, the influence of the transverse beams and their shear connections on the ultimate response of partial strength beam-to-column joints is investigated under cyclic actions and column loss scenarios by means of finite element simulations. The results show that the presence of the transverse beams provides minor beneficial effects on the primary moment resisting joints under seismic actions. On the contrary, the presence of the transverse beams gives significant effects in the case of column loss scenario, where large plastic deformations develop following the activation of catenary effects in the connected members.

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  • Current Issue
  • 3D FINITE ELEMENT MODELLING OF NOVEL STRENGTHENING SOLUTIONS FOR RC WALL/SLAB CONNECTIONS

    The aim of this study is to create a nonlinear FE model able to predict the mechanical behavior of RC wall/slab connections strengthened by using Carbon Fiber Reinforced Polymers. The experimental mechanical behavior of 4 full scale RC wall/slab connections with a reference join and 3 strengthened by FRP are investigated from members of our researcher team. The 3D finite-element micromodel of the RC wall/slab connections is conducted utilizing the FE software ABAQUS, reproducing the actual geometry of the experiments, as well as the same boundary conditions and loading as in the experimental program. The analytical investigation is carried out through an extended comparative parametric study and is focused on the quantitative influence of certain simplified modelling assumptions and several critical modelling parameters on the response of the system. The accuracy of the 3D model was assessed against the experimental results..

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  • Current Issue
  • STUDY OF THE EARTHQUAKE DISASTER RISK ASSESSMENT OF THE REGIONAL WATER SUPPLY NETWORKS

    In order to assess the earthquake disaster risk of a regional water supply pipeline network, a basic database for seismic disaster risk analysis for the water supply pipeline network was established. Using the natural disaster risk model and the information entropy theory, a seismic disaster risk assessment model for the regional water supply pipeline network was proposed. Based on the basic data for the water supply pipeline network, an evaluation index system for a comprehensive earthquake resistance and vulnerability assessment was established. The classification criteria for the earthquake risk index of the regional water supply network were proposed. The vulnerability index and risk entropy index of the water supply network of each city were calculated and compared with the existing models. ArcGIS was used to calculate and draw a distribution map of the earthquake disaster risk entropy index of the water supply networks in mainland China. The regional differences were analyzed. Taking the earthquake damage caused by the Ms8.0 Wenchuan earthquake as an example, the reliability of the risk entropy model was verified.

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