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The Performance Based Plastic design method uses pre-selected target drift and yield mechanism as performance criteria due to which total collapse of structure can be prevented. A fifteen storey Reinforced Cement Concrete frame was designed using the displacement based Performance Based Plastic Design (PBPD) method and currently used force based Limit State Design (LSD) method. The comparative seismic performance evaluation of the frames was then carried out by assessing the Response Reduction factor as well as the failure pattern. Results show that PBPD frame is found to have a higher response reduction factor as compared to the LSD frame. Also total collapse of the frame is prevented in the PBPD frame as hinges are formed in beams only. [ABSTRACT FROM AUTHOR]

Effect of increasing ductility factors on the performance of a steel moment resisting frame has been studied. The frame has been designed for ductility factors 2,3,4,5 and 6 using the performance based plastic design method which is based on the “strong column–weak beam” principle. Pre-selected target drift and yield mechanism are chosen as performance criteria. The design base shear for selected hazard level is determined by equating the work needed to push the structure monotonically up to the target drift to the corresponding energy demand of an equivalent SDOF oscillator. Plastic design as per Indian Code of practice is performed to detail the frame members and connections in order to achieve the intended yield mechanism and behavior. It was observed that as the ductility factor increases, the lateral loads decrease and hence section becomes lighter leading to optimum strength utilization. No unexpected failure is observed in most of the frames and their performance under seismic loads satisfies the “strong column–weak beam” principle. [ABSTRACT FROM AUTHOR]

The high strength materials have been more widely used in reinforced concrete structures because of the benefits of the mechanical and durable properties. Generally, it is known that the ductility decreases with an increase in the strength of the materials. In the design of a reinforced concrete beam, both the flexural strength and ductility need to be considered. Especially, when a reinforced concrete structure may be subjected an earthquake, the members need to have a sufficient ductility. So, each design code has specified to provide a consistent level of minimum flexural ductility in seismic design of concrete structures. Therefore, it is necessary to assess accurately the ductility of the beam sections with high strength materials in order to ensure the ductility requirement in design. In this study, the effects of concrete strength, yield strength of reinforcement steel and amount of reinforcement including compression reinforcement on the complete moment-curvature behavior and the curvature ductility factor of doubly reinforcement concrete beam sections have been evaluated and a newly prediction formula for curvature ductility factor of doubly RC beam sections has been developed considering the stress of compression reinforcement at ultimate state. Based on the numerical analysis results, the proposed predictions for the curvature ductility factor are verified by comparisons with other prediction formulas. The proposed formula offers fairly accurate and consistent predictions for curvature ductility factor of doubly reinforced concrete beam sections. [ABSTRACT FROM AUTHOR]

Abstract: Response modification factor is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake. Relying on this, many seismic design codes led to reduce loads. The present paper tries to evaluate the response modification factors of buckling restrained braced frames (BRBFs) utilized for rehabilitation of steel frames. Since, the response modification factor depends on ductility and overstrength, the static nonlinear analysis has been performed on building models including single and double bracing bays, multi-floors and different brace configurations (chevron V, invert V). The BRBFs values for factors such as ductility, overstrength, force reduction due to ductility and response modification have been assessed for all the buildings. The results showed that the response modification factors for BRBFs have high values. It was found that the number of bracing bays and height of buildings have had greater effect on the response modification factors. [Copyright &y& Elsevier]

Hysteretic energy spectra (simply called "VH spectra"), considering the coupling effect of maximum elasto-plastic deformation, are studied for aseismic structures. Based on self-compiled Matlab program and lots of nonlinear time history analysis for single DOF system, a set of VH spectra was presented and then according to the regression of the data an expression and coefficients about VH spectra of four types of site were obtained. The coupling effect of maximum elasto-plactic deformation and cumulative hysteretic energy could be considered in VH spectra, thus reasonably reflecting the actual elasto-plastic behavior of structure under the rare earthquake action. The results can be applied to energy-based seismic design or structure evaluation in the future. [ABSTRACT FROM AUTHOR]

The strength reduction factor spectra of constant ductility factor for bi-directional ground motions is developed based on original theories by considering the multi-component earthquake excitation and coupled characteristics of structural response. The statistic formula of strength reduction factor spectra is improved in this paper. The effects of ductility ratios and period ratios of two principal axes on nonlinear response of systems under bi-directional earthquake excitations are discussed based on statistic analysis of 178 recordings for hard site, medium site and soft site. By the sufficient statistic analysis, the simplified formula of strength reduction factor design spectra of constant ductility factors is established, which is the foundation for forming the inelastic design demand spectra for structures subjected to bi-directional ground motions. [ABSTRACT FROM AUTHOR]