Sharif Digital Repository

In recent decades, most of the codes have placed a high value on Performance Based Design of structures; however, these methods are computationally complex and time-consuming, and caused researchers to seek new and efficient methods to investigate performance of structures under different intensities of seismic loading. This issue is much more obvious when optimum design of structures, which requires repetitive analysis, is investigated. In the present research, using Endurance Time analysis, we are trying to provide better insights into the dynamic behavior of structures in continuous performance levels. Then, as a first step, we will use the verified method to find the optimum outline of... 

Nowadays using traditional hollow clay brick in buildings to make walls and partitionsisvery common. Non-load-bearing walls in buildings are used as architectural elements for design purposes and protecting the people that are inside the building from cold , heat and sound pollution .Due to the new technologies and developing building codes interms of structure , non-load-bearing walls behaviour that is always neglected seems necessary to be considered. In this research we have investigated the static and dynamic behaviour of a patented non-load-bearing wall made up of a claybrick system with specially-designed-precision grooved faces that eliminates conventional cement mortar and results... 

The existing statistical studies implies that in Iran like most of developing countries, the great percent of houses are traditional. Statistics of the most disastrous current quakes also show damages caused by masonry structures in developing countries. The main problem of brick and masonry structures especially the unreinforced one is their weak performance against quake. Different methods are use to analyse the seismic performance of this structures. The modern endurance time method is a kind of time history analysis using standard increasing accelerograms which examines different parameters of structure behavior during excitation actions. In this project we analyse these structures using... 

In the earthquake conditions, the collapse of cooling towers can stop power station activities and heavy financial losses that can be led increasing disaster dimentions finally. In this thesis for analysis of concrete hyperbolic cooling towers and generally for analysis of shell structures, the endurance time (ET) method benefits are used. Also with comparision between ET and standard time history method (THA), accuracy and probable errors of ET method are discussed. It should be noted that ET method is a new time history based method of seismic analysis expect that in this method, structure is imposed under specific intensifying acceleration functions. ET method is capabable for nonlinear... 

In recent years, by development of computer and analytical software, engineers intended to do complicated and delicate dynamic analysis instead of static ones. This cause reduction in uncertainty in structures analysis and designing, that improves environmental, economical, and safety performance. Currently there are two common methods which are accepted in major building codes, they are spectral and time history dynamic analysis which the former analyzes structures by using design code spectra based on determination of structures’ dynamic haracteristics, and the latest do it by imposing ground motions on the structure. The spectral dynamic analysis method has some errors and causes... 

With improvement of design and analysis techniques, use of irregular bridges has been expanded. These improve the aesthetics of urban spaces as well as providing shorter highways in impassables. Horizontally curved bridges are among the type of structures, which needs to be designed based on three-dimensional analysis. In this thesis, three-dimensional nonlinear analysis was performed by Endurance Time Method (ET) on horizontally curved bridges. Nonlinear models have been analyzed under ET acceleration functions. Comparing ET results in DBE level with earthquake responses, the difference between these two methods were determined. ET estimated earthquake responses with good accuracy;... 

In high seismically active regions, such as Iran, shear walls are one of the preferred seismic force resisting system.The efficiency of reinforced concrete bearing walls for resisting lateral forces and controlling lateral drift in high-rise buildings has long been recognized. But in recent decades shear wall dominant buildings or so called tunnel form buildings have been increasingly constructed as the multi-story reinforced concrete buildings. The purpose of this thesis is to assess the seismic performance of concrete shear walls that provide gravity as well as sesmic resistance for this kind of buildings. The studied walls were assumed to be part of 5- 10- 20- and 40- story residential... 

Bridge is one of the most important structure that are used in urban transportation system. In recent decade, international standards and codes have introduced “Performance Based Design” for structure design criteria. Large and complex dynamic and time history analyzes are obstacles against this method; especially in finding optimum design that requires repeated analyzes. In this research, application of Endurance Time (ET) method in seismic design of urban concrete bridges has been evaluated and value based design of them has been presented. In ET method, seismic performance of structures under artificial intensifying accelerograms is investigated. Performance of structure in... 

This study proposes a novel type of metallic yielding damper called block slit damper or BSD. This damper is a slit damper with very low height to thickness ratios. This device is buckle resistant, possesses high shear capacities, and is more economical than SSD devices with high height to thickness ratios. Based on theoretical analysis the formulation for the BSD device’s main parameters is derived. Then to investigate the hysteretic behavior of the proposed devices, 5 specimens with different aspect ratios (height-width ratios) were manufactured and tested in a quasi-static manner. The tests revealed that by reducing the aspect ratios, the shear and energy dissipation capacity increases... 

Modified Fish-Bone (MFB) Model and Consistent Generic (CG) Model are simplified Multi-Degrees-of-Freedom (MDOF) models, proven to be valuable tools in estimating seismic demands of moment-resisting frames, aimed to reduce the computational costs by decreasing the number of degrees of freedom. The preliminary expansion of these simplified models for steel moment resisting frames (SMRFs) were proposed by considering elastoplastic behavior and is not able to take into account stiffness and strength deteriorations in nonlinear dynamic behavior of structures. However, behavior deterioration affects seismic demands of SMRFs under intense earthquakes. For this reason, the present study is done to... 

Endurance Time Method (ET) is a dynamic analysis in which structures are subjected to intensifying accelerograms and performance of them are assessed based on their response at different excitation levels. Duration consistency of current ET accelerograms has not been directly considered. Strong motion duration can strongly influence the response of structures and foundations especially when they encounter degrading characteristics in their materials. In this study, duration related properties of ET accelerograms and ground motions are compared. These properties consist of strong motion duration, cycles number of motion and number of nonlinear cycles which a structure should sustain when it... 

Endurance Time (ET) is a fairly comprehensive analytical method based on time history analysis applied for evaluating structural systems excited by dynamic loading of earthquake. In such evaluation assessment measure is based on endurance time of structure versus applied accelerogram function and parameters such as stiffness, lateral resistance, period of vibration and dynamic characteristics are not used directly. In this research nonlinear dynamic analysis of elevated steel tanks with laterally braced framed tower under the loading of earthquake records and ET accelerograms was studied and effectivity of ET method in analyzing such elevated tanks was verified. Due to complication of... 

The aim of this research is to evaluate and compare the performance of common concrete and steel structural systems in the construction industry under various parameters, including initial construction cost, lifetime seismic losses, end-of-life costs of the structure, and simultaneous consideration of these parameters. In this regard, a residential building with real architectural plans and details was designed for five different structural systems, both concrete and steel, and their initial construction costs were calculated using executive drawings. Then, using Endurance Time dynamic analysis, the structural responses under probable seismic hazard levels was determined, and based on... 

The objective of this study is to design a real structure based on value using the endurance time method, which is designed according to common design codes. In the value-based design of this structure, a variation of the lateral load coefficient has been used for the design of the investigated structural specimens. The term "value" in this research refers to the total costs incurred over the lifespan of the structure. The initial construction costs of the structure and the life cycle costs are optimized in the value-based design process. The initial construction cost in this research consists of two parts: the first part is variable costs that arise from the consumed materials in the... 

The sustainability of urban infrastructure is assessed in three integral economic, social, and environmental dimensions. This study focuses on advancing a design approach based on value through the optimization of the life-cycle cost of steel moment frames, considering sustainability indicators by utilizing endurance time method analysis.In this path, the dimensional specifications of steel frame sections are selected optimally using an automated process with the objective of minimizing the cost of the structure's life cycle as the objective function and code specifications as optimization constraints. The cost of the life cycle, includes material extraction and production, transportation,... 

This study proposes an efficient risk-targeted framework for integrated optimal seismic design and quantifying target safety of steel Special Moment-Resisting Frames (steel SMRFs) with and without various passive damping devices such as Buckling-Restrained Braces (BRBs), Friction Dampers (FDs), and Fluid Viscous Dampers (FVDs). This framework provides an automated design procedure formulated as a constrained single-objective optimization problem to achieve the minimum Life Cycle Cost (LCC) within the Particle Swarm Optimization (PSO) algorithm and can be the basis of current seismic codes for target safety calibration. LCC includes initial construction cost and lifetime seismic losses such... 

In recent decades, most of the codes have placed a high value on Performance Based Design of structures; however, these methods are computationally complex and time-consuming, and caused researchers to seek new and efficient methods to investigate performance of structures under different intensities of seismic loading. The Usage of Endurance Time method (ET) and thus reducing the size of analysis can be a useful tool for excuting Performance Based Design of structures. Endurance Time analysis is based on time history analysis, but in this method structure subjected to an intensifying acceleration function and different damage indices of the structure are evaluated through analysis time. The...