نشریه آنالیز سازه - زلزله
سال دوازدهم شماره 3 (پاییز 1394)

Concrete- Filled Double Skin Steel Tubular (CFDST) columns are members of the Concrete- Filled Steel Tubular columns (CFST) family. In CFDST the steel skin and the existing concrete affect each other behavior so that the concrete prevents buckling of the inner and outer steel skins and the both steel skins under load result in the development of the confinement force and subsequently increase the ductility of the concrete and prevent the concrete from brittle damage. To ensure the accuracy of the finite element modeling, the experimental results were compared with the finite element and the accuracy of the modeling was verified. In this research, the section geometry, under monotonic and cyclic loading was investigated. The out-come results show that the CFDST columns have a good ductility, higher energy absorption capacity during an earthquake event and improved behavior under cyclic loading in comparison with CFST columns

Light weight construction is one of modern topics in civil engineering, the topic of reducing weight of structure is achiev by use of new technique and optimization of construction procedure. Consideration to wide use of concrete and enviromental pollution to the reason of using cement, investigators are trying to replace a part of cement by natural and artifitial pozzolan and nano particle materials.
In this study the use of natural pozzolan zeolite with different percents 0, 5, 10, 15, 20 investigated and longterm and short term effects on the compression and tensile strenght on semi light weight concrete at the age 3, 56, 90 days were studied and compared with control specimen. Result shows that 5% and 10% replacement of zeolite improve compression strength at the age of 3, 90 days, and for age of 56 days most improvement is related to 15% replacement by zeolite

perviousconcrete is a special kind of concrete which has a high degree of porosity and one of its major applications is in the roadway pavements. Todays, due to transportation importance, using of new materials in land, sea, airand railway transportation infrastructures is among hot research topic. Pervious concrete is one kindof the rigid pavement which has great advantages include; high permeability, proper hydraulic conduction, surface water filtration and to the underground water sourcesinjection. Despite having many advantages, its low compressive strength is one of its disadvantageswhich indicate demands for deeperstudies to increase the compressive strength of this type of concrete. In this research, a series of experimentaltestsis done on typical aggregate samples with different material and graduation, in first step their physical and specious properties was examined and then after preparation of different mix designs for making perviousconcrete sample, properties of obtained concrete samples like: permeability, porosity, and compressive strength were investigated, after that, conducting the tests on various specimens, the results were analyzed. Finally, based on the results and analyses of the conducted tests, the optimum mix designs were introduced based on their application.

This paper aims to analyze the sustainability and vulnerability of Davazdah Emam Dome that is located in the historical context of Yazd city against to Earthquake. This dome dated back to Al-Muzaffar era (429 A.H.) and it is the oldest monument with inscription in Yazd. Baked bricks and traditional materials are used to build this dome. In this paper a 3D modeling of dome was made in AutoCAD and carried out its structural analysis in Ansys software. After its structural analysis under own weight and modal analysis and earthquake analysis (Naghan area), we surveys the results and identify the vulnerable and sensitive areas of dome with lowest cost and in a short time. Also the structural characteristics of dome are specified.

Situ concrete piles, are the most widely used type of deep foundation. In Iran experience shows, that technical problems and economic performance by avoiding the use of ordinary concrete with a slump an extremely high in these types of candles. Poor and low compress resistance, durability and high water permeability in the subsurface environment, the effects of this type of concrete planning. The excellent strength, permeability to ensure proper compaction, concrete ease and speed up the planning run, the significant advantages of self-compacting concrete. These benefits are especially situ concrete pile planning, most appear to be. In This paper compares core strength situ by taking samples from two typical arrangement of pile ordinary and self-compacting concrete and important results have been obtained. The core samples, to a depth of 14 m in which different levels of ground benchmark are tested show that the use of self-compacting concrete has technical and economical advantages, and notable administrative lead to greater uniformity in resistance acquisition, located in the upper part of the pile is. This section, the maximum stresses due to vertical and lateral loads. Therefore, the use of self-compacting concrete in deep foundations, can widely replace traditional methods.

In this paper the algebraic Riccati matrix equation is used for eigen-decomposition of per-symmetric matrices. This is achieved by similarity transformation and using the algebraic Riccati matrix equation. The process is the decomposition of matrices into small and specially structured sub-matrices with low dimensions for easy finding of eigenpairs. Example show the efficiency of the proposed method.

There are many concrete building without enough resistant against earthquick that need to seismic retrofitte. Using steel bracing is an usual way to seismic retrofitting in current years. For the suitable performance in this method , the connection between steel bracing system and concrete frames is very important. In recent years some experimental researches is done in this field and several method is recommended for connection. For determinating the suitable connection , in this research 4 RC frames retrofitted by using steel bracing system with 4 details in connection and 1 RC frame without bracing is modeled by using the finite elements method in Abaqus software. the strength of connection 's elements , stiffness of system and cracking in RC frames are investigated and compared in every model.
Results show that the connection between brace and RC frame by bolt to beam and column , also by steel jacket which fixed to column have suitable performance and other types of connection haven't required performance

In this paper, with the introduction of a new Knee Brace Frame the seismic behavior of steel frames braced with knee brace compared with X and Chevron brace frame are discussed. For this purpose, the braced steel structures, with the number of floors three, five and eight-story frame with four meters three-span by using pushover analysis are analysed. Considering that lateral displacement structures parameter is an effective parameter on failure of structural and non-structural members, The amount of lateral displacement of steel frames braced with different types of braces, and also given the importance of ductility coefficient such behavior braced steel frames are compared with each other. Studies have shown that, the Knee Brace Frame, ductility and stiffness conjoined provides.