Sharif Digital Repository

Over the past few decades considerable experimental and numerical studies have been conducted on the Reinforced Concrete columns to Steel beams (RCS) connections. Most of those researches have focused on studying the joint failure modes and ultimate joint strength of specimens utilizing strong beams and columns with weak joints. In this paper, two interior RCS connections were designed based on the Strong Column-Weak Beam (SCWB) criterion. Both specimens were tested under quasi-static reversed cyclic loading. The tested specimens were modeled by a finite element method, which verified with experimental results. Several models with different joint details were investigated using the verified... 

Daily development in civil engineering arena and the importance of economical aspects in the design of structures have motivated the engineers to shift their approaches from designing upon strength to designing upon performance. This is of more importance regarding the forces induced by earthquakes which have unpredicted and random nature. However, it is not possible to design or assess exactly the structural performance against strong ground motion using analytical methods which are applied for static loads and therefore precise dynamic analysis methods are needed. Despite significant progress in the analytical methods and engineering software, using nonlinear time history analysis is very... 

The endurance time (ET) method is a time history-based dynamic pushover analysis procedure that utilizes special intensifying acceleration functions for estimating the seismic performance of structures at different excitation levels. One of the potential applications of the ET method is in the three-dimensional analysis of buildings considering multidirectional excitation. In this paper, a procedure for multi-component analysis by the ET method has been developed. Several steel moment frames with heights from 9.6 to 48 m were designed according to the Iranian National Building Code. By applying the proposed algorithm for three-dimensional analysis of structures by the ET method, these frames... 

One of the methods in limiting tensile stresses in arch dams and removing stress concentrations at the dam-foundation interface is setting the dam body on a concrete saddle called a Pulvino. In the present study, the effects of Pulvino and peripheral joints on the static behavior and seismic performance of arch dams are investigated. Dez Dam with a height of 203 m was selected as a case study and all contraction joints of the dam body were modeled using the discrete crack approach based on as-built drawings. Also, the surrounding rock was modeled as a mass-less medium tied to Pulvino. The dam-reservoirfoundation system was analyzed under static loads accounting for stage construction... 

A new concept to determine state of the damage in concrete gravity dams is introduced. The Pine Flat concrete gravity dam has been selected for the purpose of the analysis and its structural capacity, assuming no sliding plane and rigid foundation, has been estimated using the two well-known methods: nonlinear static pushover (SPO) and incremental dynamic analysis (IDA). With the use of these two methods, performance and various limit states of the dam have been determined, and three damage indexes have been proposed on the basis of the comparison of seismic demands and the dam's capacity. It is concluded that the SPO and IDA can be effectively used to develop indexes for seismic performance... 

As a matter of fact, it is necessary to have the values of Response Modification Factor R, Over-strength Factor Ω0, and Deflection Amplification Factor Cd in order to design seismic-force-resisting systems according to design and loading codes. This study is intended to evaluate these factors for a structural lateral bracing system called Chevron Knee Bracing (CKB). In this type of bracing, the knee elements assist the system to dissipate energy through the formation of plastic flexural and/or shear hinges within the presented bracing system. The approach utilized in this study is according to FEMA P695 based on low probability of structural collapse and involves nonlinear static and dynamic... 

In this paper, a practical method is developed for performance-based design of RC structures subjected to seismic excitations. More efficient design is obtained by redistributing material from strong to weak parts of a structure until a state of uniform deformation or damage prevails. By applying the design algorithm on 5, 10 and 15-storey RC frames, the efficiency of the proposed method is initially demonstrated for specific synthetic and real seismic excitations. The results indicate that, for similar structural weight, designed structures experience up to 30% less global damage compared with code-based design frames. The method is then developed to consider multiple performance objectives... 

Liquid storage tanks are essential structures that are often located in residential and industrial areas; thus an assessment of their seismic performance is an important engineering issue. In this paper, the seismic response of unanchored steel liquid storage tanks is investigated using the endurance time (ET) dynamic analysis procedure and compared to responses obtained for anchored tanks under actual ground motions and intensifying ET records. In most cases, the results from ground motions are properly obtained with negligible differences using ET records. It is observed that uplifting of the tank base, which is closely related to the tank aspect ratio, has the greatest significance in the... 

In order to estimate the seismic demands at the performance level, the inelastic behavior of concrete structures should be considered. Incremental dynamic analysis (IDA) based on a nonlinear response time history analysis (NL-RHA) is considered to be the most accurate method in seismic demand calculations. However, modal incremental dynamic analysis (MIDA), based on the equivalent single-degree-of-freedom (SDF) oscillator, is also often used in studying structural engineering performances. As the MIDA method has usually not been applied to reinforced concrete (RC) structures, in this study an attempt is made to investigate the performances of RC frames and to compare the results obtained... 

The endurance time method (ET) is a dynamic analysis procedure in which intensifying dynamic excitations are used as the loading function. Seismic performance is evaluated over the entire range of equivalent seismic intensities of interest in each response history analysis, considerably reducing computational demand. In this paper, a general methodology for performance-based retrof itting of typical steel frames by the ET method is discussed. A baseline steel momentresisting frame is considered, and its seismic performance is evaluated by the ET method, considering viscous dampers and shear wall panels as strengthening alternatives. Each retrof itting option includes several design... 

In this paper, the behavior and performance of a new type of bracing system called Hat Knee Bracing (HKB) is investigated in low-rise multistory steel structures. This novel form of resistant system, which provides reasonable stiffness in moderate earthquakes, consists of a V shaped knee member connected to mid span of the beam and the brace members. In this research work, the "FEMA P695 evaluation method" is utilized in order to explore the nonlinear behavior of the HKB frame, and quantification of three seismic performance factors: Response Modification Factor, Over-strength Factor, and Deflection Amplification Factor. The seismic response simulation of archetype frames is performed using... 

In this paper, application of the Endurance Time (ET) method in the performance-based design of steel moment frames is explained from a conceptual viewpoint. ET is a new dynamic pushover procedure that predicts the seismic performance of structures by subjecting them to a gradually intensifying dynamic action and monitoring their performance at various excitation levels. Structural responses at different excitation levels are obtained in a single time-history analysis, thus significantly reducing the computational demand. Results from three analyses are averaged to reduce the random scattering of the results at each time step. A target performance curve is presented based on the required...