جستجوی مقالات مرتبط با کلیدواژه « برآورد خسارت » در نشریات گروه « عمران »

Application of self-centering rocking walls is now widely accepted as a viable alternative to removal of some of the common seismic defects of conventional shear walls including residual drift and significant damage to the base of walls. Despite the different experimental studies on the seismic performance of rocking walls, few numerical models have been developed to predict the seismic response and damage extent of these walls under seismic loading. The main objective of this study was to present a practical method for numerical modeling and damage estimation for nonlinear behavior of post-tensioned (PT) concrete rocking walls when exposed to earthquake excitations. To this end, PERFORM 3D software was utilized to model self-centering rocking walls. The walls were subjected to a set of seven spectrum compatible ground motions at different intensity levels. To ensure the accuracy of the modeling, the numerical results of the nonlinear analysis were compared with the experimental results, and the results showed that the developed model could predict the behavior of the wall during all ground motions with acceptable accuracy. Moreover, in this study, a damage index was employed to estimate the extent of damage in the developed numerical model. Good agreement between the observed damage in the shake table tests and estimated damage in the developed model was observed. The results of this study indicated that the method for modeling the seismic behavior of the rocking wall could appropriately predict the response and damage extent of these walls under earthquake loading.

Blast loads may result Irretrievable damages in structures due to their high amount of applied energy to them during a short period of time. Strengthening and rehabilitation of the structures subject to these sort of loads would be a proper approach to mitigate these damages. Among the available approaches, use of composites so-called Fiber Reinforced Polymers (FRPs), because of their desire properties such as ease in installation and high strength to weight ratio, has been considered the most common solution in recent years. These composites, however, possesses some disadvantages such as low resistance against fire, low glass transition temperature, difficulties in application at low temperatures, impossibility of application on wet surfaces and lack of vapor permeability which have led to use innovative composite materials as alternative. These are normally made of cementitious matrix reinforced by continuous fibers (FRCM). These composites with cement based matrices have good mechanical performances, excellent resistance to high temperature and fire, and also good vapor permeability. Moreover, they can be applied on wet surfaces and in cases of low temperature. Therefore, FRCM materials may constitute an alternative to FRP materials for the strengthening of RC structures. In this paper, performance of RC columns which are subject to blast loading and strengthened with FRP and FRCM composites is investigated using Pressure-Impulse (P-I) diagrams. The results obtained in this study demonstrate that strengthening of structures by FRCM is more efficient in comparison to that of FRP in most cases of damages and therefore could be implemented to protect structures better against blast loads.

Earthquakes pose inevitable damage and loss of life in structures. Seismic isolation has proven to be an eective method to reduce the seismic vibration and mitigate seismic losses and damage costs. The isolator drastically reduces the main frequency of the structure and subsequently lowers the acceleration of the oors. While this exible layer protects the building from destruction, it undergoes a relatively large displacement demand. Isolated structures as well as xed structures could suer from inelastic deformation and serious damage under intense seismic ground motions. Performance-based seismic design (PBSD) is a concept that permits the design of buildings with reliable understanding of the risk of life, occupancy, and economic loss that may occur as a result of future earthquakes. Also, Seismic loss estimation method combines seismic hazard, structural response, damage fragility, and damage consequences of allowing quanti cation of seismic risk based on seismic performance of a building is expressed as the probable damage and resulting consequences of a building's response to earthquake shaking. Nonlinear 4-story archetypes of conventional special moment resisting frame and isolated intermediate moment resisting frame were compared with each other under Far-Field and Near-Field ground motions. Detailed three-dimensional (3D) numerical models of the structures were developed in OpenSees software and Performance Assessment Calculation Tool (PACT) was used for the loss estimation of archetypes. The decision variables in this study were de ned as expected annualized repair cost or nancial losses (EAL) and expected annualized fatalities (EAF). The analysis results showed that seismic isolation reduces collapse probability, EAL and EAF in superstructures signi cantly and can be cost eective in mitigating seismic risk. Seismic isolation reduces EAL by 72% and 67% under Far-Field and Near-Field ground motions, respectively. Furthermore the result of this study showing that the eectivity of isolation system decreases in Near- Field compared with Far-Field ground motions. The economic feasibility studies showed that if isolation system is used, pay-back period times are around 14 and 18 years under Far-Field and Near-Field ground motions, respectively. The bene t of loss estimation approach is an improved method to assess the eectiveness of isolation system in terms of loss estimation.