In this paper, overstrength, ductility and response modification factor of buckling restrained braced frames (BRBF) dual system were evaluated. To do so, building with various stories and different bracing configuration including diagonal, X, chevron (V and inverted V) bracing were considered. Static pushover analysis, nonlinear incremental dynamic analysis and linear dynamic analysis have been performed using SAP2000 software. The effects of some parameters influencing response modification factor, including the height of the building and the type of bracing system, were investigated. In this paper seismic response modification factor for each of BRBF dual systems has been determined separately and tentative value of 10.4 has been suggested for allowable stress design method.

The goal of this paper is to propose input energy spectra applicable to seismic design of structures based on Iranian earthquakes. In terms of input energy, these spectra represent the load effects of a strong earthquake that a structure may encounter during its lifetime. For this purpose, from among 1800 existing earthquake records in Iran, 110 records were selected. By using these records and through dynamic response analyses, the design input energy spectra for four ground types, defined by the Iranian earthquake code of practice, have been derived.

Nowadays public buildings, located in residential areas, are occasionally affected by unwanted and unexpected events. Structural robustness makes balance between local damages and comprehensive ones. This study suggests a new method to evaluate the risk-based robustness index in structures. Two critical events, namely earthquake and blast, are considered to evaluate the risk-based robustness index, both of which are regarded as compatible and interdependent so that an earthquake-related blast happens simultaneously or a little after the quake and as a result of gas leak or damage in mechanical and thermal facilities. Based on uncertainty parameters in both critical events, risk-based robustness index (as a result of earthquake and blast) also called "seismic-explosion risk-based robustness index'', is brought up by generating scenarios. Finally, in order to understand this method better, the article gives an example to evaluate this index on a reinforced concrete moment frame building. Eventually the results of this analysis are discussed.

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In this paper, interruption risk in construction activities of bridge projects is assessed in order to identify the main causes of its occurrence and also to determine the potential outcomes resulted from the risk occurrence. To do this, fault tree and event tree analysis (ETA) methods are applied. As the application of the traditional approach of these two methods is difficult in many cases due to limited access to information, fuzzy arithmetic can be considered as a useful tool. In this research, first, fault tree structure is created according to consequences resulted from the Delphi method. Then, the probability of risk occurrence is calculated by applying fault tree analysis (FTA) based on fuzzy logic. By establishing the structure of fault tree related to the failure risk of mitigation strategies, the main causes relating to failure of strategies are identified. The structure of the event tree is created using the obtained results; moreover, the expected monetary value (EMV) of risk event is computed. Finally, to validate the results obtained, a model is created by Monte Carlo simulation and then the results obtained by applying the two methods are compared. The EMV of the risk event evaluated in this paper is determined to be 9.93% of the project baseline cost.

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