m. mashayekhi

It is well accepted that an urban region's seismic resilience is directly related to the seismic resilience of the local water systems. Pipelines having low earthquake resistance generally include old pipes and those susceptible to corrosion. The seismic vulnerability of the water transmission pipelines can be evaluated along with the geologic hazards such as landslides, liquefaction, fault movement, etc. In this study, GIS-based analyses are implemented for one of Tehran's main water transmission pipelines, which transfer Mamloo Dam water to Tehran's southern regions, by considering the four most probable earthquake scenarios to evaluate post-earthquake serviceability of the studied pipeline. Transient Ground Deformation (TGD) due to seismic wave propagation, and also Permanent Ground Deformation (PGD), which may result in liquefaction (lateral spreading, and ground settlement) and landslide, are regarded as destructive earthquake effects on the water transmission pipelines. A restoration curve is also developed for the worst scenario to investigate the adequate post-earthquake water supply throughout the service area and ensure rapid system recovery. Results show that the water serviceability index regarding the worst earthquake scenario (Rey fault activated) is 28%, which means that more than 72% of the study area's population will experience severe disruption of water availability in a potential earthquake.

Performance-based optimization of energy dissipation devices in structures necessitates massive and repetitive dynamic ‎analyses. In the endurance time method known as a rather fast dynamic analysis procedure, structures are subjected to ‎intensifying dynamic excitations and their response at multiple intensity levels is estimated by a minimal number of analyses. ‎So, this method significantly reduces computational endeavors. In this paper, the endurance time method is employed to determine the optimal placement of viscous dampers in a weak structure to achieve the desired performance at various hazard levels, simultaneously. The viscous damper is one of the energy dissipation systems which can dissipate a large amount of seismic input energy to the ‎structure. To this end, hysteretic energy compatible endurance time ‎ ‎excitation functions are used and the validity of the results is investigated by comparing them with the results obtained from a suite of ground motions. To optimize the placement of the dampers, the genetic algorithm is used. The damping coefficients of the dampers are considered as design variables in the optimization procedure and determined ‎in such a way that the sum of them has a minimum value. The behavior of the weak structure before and after rehabilitation is also investigated using endurance ‎time and nonlinear time history analysis procedures in different hazard levels.‎

This study aims at determining the critical seismic intensity at which cracks are expected to develop in a concrete arch dam. This intensity is referred to as crack initiation intensity. The crack initiation intensity measure implies that earthquakes with the intensity measure higher than this value are expected to induce cracks in the arch dam. This quantity is an indicator for seismic evaluation of arch dams. Determining this parameter using conventional time history analyses requires multiple trials and errors applying several up and down scaling of a suite of ground motions which can be very time consuming. As an alternative method, endurance time method is well suited for this kind of study. In the endurance time method, structures are subjected to predefined intensifying acceleration time histories and all intensity measures are continuously covered in a single time history analysis. The continuous coverage of intensity measures in the endurance time method provides a tool to conveniently determine the transition points such as crack initiation in a single time history analysis. In this regard, a framework is proposed and then applied to Morrow point dam, a doubly curved arch dam, as a case study. Results are obtained by using three different endurance time excitation series; ‘kn’, ‘kd’, and ‘lc’. The aim of using three endurance time series was to compare their differences in dynamic analysis of arch dams. Observations indicate the acceptable compatibility of different series of endurance time excitation. In order to investigate the accuracy of the results obtained by the endurance time method, the dynamic analysis of the arch dam subjected to ten ground motions scaled by the calculated crack initiation intensity measure is performed. It is shown that the proposed method can be conveniently applied for determining the crack initiation intensity.

This paper aims to investigate the effects of motion duration on the structural seismic demands, seeking potential correlations between motion durations and structural responses at several seismic intensity levels. Three seismic intensity levels with 100years, 475years, and 2475years earthquake return periods (RPs) are first considered for correlation computations. Spectrally matched ground motions are employed to isolate the contribution of duration from the effects of ground motion amplitudes and response spectral shape. Four single degree of freedom systems derived from four real reinforced concrete structures are studied, where both degrading and non-degrading equivalent SDOF systems are included for structural modeling. Results show a low positive correlation between motion duration and structural displacement demand, but this correlation increases with an increase in earthquake RP. It is also investigated whether or not this insignificant positive correlation has an impact on the incremental dynamic analysis curves. The spectrally matched ground motions are divided into two distinct groups in this case: short  and long duration ground motions. The comparison of incremental dynamic analysis of these two groups at the collapse limit reveals that long-duration ground motions can cause up to a 20 percent decrease in the spectral acceleration demand of considered structural systems.