نشریه آنالیز سازه - زلزله
سال شانزدهم شماره 2 (تابستان 1398)

In this study, 2 reinforced concrete 3D building frames for a 28-storey building are going to be considered and analyzesThese frames are in both X andYdirections with tube in tube structural system and a flat plate roof with rigid internal core in the shape of H, in a relatively high risk zone (A=0.3 g) on two kinds of soil, with and without soil-structure interaction.The goal of this study is to determine the maximum drift and displacement of the storeys under gravity loads(dead  live) and lateral load of earthquake. A discrete model based on a buried footing Cone Model in homogeneous half space of volf and meek is used to model the soil under the foundation and also to determine dynamic stiffness coefficient and Soil damping cofficient and a substructure method with the footing rigidity assumption is used to analyze the frames with the soil-structure intraction  effect. A dynamic analysis of the nonlinear timeline history of seven accelerograms is used to analyze earthquake load and geometric modeling of all  frames with internal core has been done in sap2000-V17software.The results show that the maximum drift and displacement of the storeys with soil-structure interaction in X and Ydirection was not different with the one without interaction and that they are equal. By changing the type of soil with and without soil-structure interaction, the maximum drift of storeys in X direction had a descending increment process of 22 percent and in Y direction, had 25 percent is increment.

Structures are often subjected to lateral loads due to earthquakes, winds, and waves of water. It is very necessary to predict and measure the "load-deflection" behavior of the pile group, as well as its strain behavior, in order to create a safe and economical design. The behavior of piles embedded in soil, placed under the lateral load, is typically modeled and analyzed using the Winkler nonlinear springs method. In this method, the soil-pile interaction is modeled by nonlinear curves of P-Y in a way that P-Y curve modifies and adjust the single pile using a p-multiplier  for each row of piles in the group. The factor depends upon the configuration of pile group and the pile spacing. The value of this factor for the leading rows are considered higher and for the trailing rows lower. The present study was conducted to investigate the effects of various parameters, such as the pile spacing in the group and different layouts on the  factor. The  factor obtained from this study has good compatibility with the results of the full-scale test on pile group. The results show that the value of the  factor for pile groups with different layouts of 2.5-diameter pile spacing was in the range of 0.42 to 0.54, which is very close to the value of  obtained by previous study.Structures are often subjected to lateral loads due to earthquakes, winds, and waves of water. It is very necessary to predict and measure the "load-deflection" behavior of the pile group, as well as its strain behavior, in order to create a safe and economical design. The behavior of piles embedded in soil, placed under the lateral load, is typically modeled and analyzed using the Winkler nonlinear springs method. In this method, the soil-pile interaction is modeled by nonlinear curves of P-Y in a way that P-Y curve modifies and adjust the single pile using a p-multiplier for each row of piles in the group. The  factor depends upon the configuration of pile group and the pile spacing. The value of this factor for the leading rows are considered higher and for the trailing rows lower. The present study was conducted to investigate the effects of various parameters, such as the pile spacing in the group and different layouts on the  factor. The  factor obtained from this study has good compatibility with the results of the full-scale test on pile group. The results show that the value of the  factor for pile groups with different layouts of 2.5-diameter pile spacing was in the range of 0.42 to 0.54, which is very close to the value of  obtained by previous study.

Concrete Filled Tube (CFT) steel columns have become increasingly popular in recent years due to their many advantages in industrial and high-rise buildings, bridges, piers and piles. These columns often run in circular shapes. The main reason for this is that circular sections create more confinement than other sections in core concrete. This caused the circular sections to be used more frequently in the CFT columns than other sections. But sometimes it will be impossible to use circular sections and will have to use special forms, such as square and mesial sections, and L and T-shaped sections in some parts of the building. Due to the importance of this issue in this paper, we tried to introduce and investigate the mechanical behavior of CFT columns with T-shaped geometrical cross section and to investigate the parametric effect of steel wall thickness, and concrete compressive stress, on the mechanical capacity and behavior of these columns. Finally, after conducting the research, it was found that in CFT columns with T-geometrical cross section, between the effect of steel wall thickness and the type of concrete, the steel wall thickness parameter is the most influential parameter on the bearing capacity of the CFT columns, and also between the steel wall thickness parameter and the cross section height, Influence of elevation changes on ductility, hardness, and bearing capacity of the cross section It is greater than the thickness of the steel wall.

Main idea of present research is evaluation of statically behavior of soil-steel structures under military vehicles loading. For this purpose, a soil-steel structure with horseshoe shape profile with maximum span equal to 9.88 meters considered. According to Code No.139 Tank weight affected on numerical model. Plates dimensions based on CHBDC code were selected. In present study, analyses in three position were performed. These positions are based on variations of earth fill, types of soil-steel structure plates and location of loading. Numerical analysis was carried out by Plaxis program in 2D condition and according to finite element method. Results of this study showed that, in soil with suitable geotechnical properties (i.e. increasing elastic modulus and internal friction angle), stability of soil-steel structure go up and settlement values decreases. Also, types of plate in soil-steel structure can be effective in behavior. So that, plates with high thickness and more flexibility is useful for application in soil-steel structure.

Infills increase the stiffness of their surrounding frame. As a result, infilled frames attract more lateral loads compared to similar frames without infill. Subsequently, infilled frames differ from frames without infills in terms of internal forces and other properties, in addition to stiffness, strength, and period. And after the first cycles of lateral loading and after brittle fracture of infills, these forces are transferred to the frame and cause fracture and crushing of the frame. Furthermore, the asymmetric distribution of infills in the plan increases the distance between the center of stiffness and the center of mass and induces torsion in the structure. In this study, buildings with the same floor plan and different heights (three, five and eight stories) and three different soil types (based on 2800 code) are modeled. For every case, the structure was modeled as a frame without infill, masonry infilled frame and 3D panel infilled frame. Besides, static and spectral dynamic analyses were carried out using ETABS software and the effect of infill on reducing the length of the shear wall and construction cost was examined. Results revealed that the smaller floors, the greater shear wall length reduction trend and this is more in the three-story building. It also reduces the dimensions of the beam and column elements and the amount of rebar by using a 3D panel.

In this paper, the effect of using a (TLD) damper on the seismic behavior of the Concrete Moment Frame Structures is investigated. Modeling ANSYS software is done. Modeling with structural elements including beams and columns in a concrete framing frame of Beam 189 and a nonlinear dynamic analysis was used. The seismic behavior of the structures was investigated under the earthquakes of Kobe, Chichi and Tabas. The TLD Damper in the 5, 10 and 15 buildings were compared and compared. The effect of different damper positions on different structures of the structures was investigated. The effect of different damper positions on different structures of the structures was investigated. Using of a damper can cause plastic joint failure in the joints. It was also found that depression position is an effective parameter on the seismic behavior of the studied structures. For the 15th floor structure, the use of a damper on the fifth floor of the structure reduces the roof structure displacement by 10.5, in the fifth floor, 17 percent, and 53 percent in the fifth floor. In the structure of the ten floors of the dam, it reduces the displacement of the roof structure by 50%. In the 10-story structure, the dampers in the 5-day delay reduce the roof's displacement by 33%. In the five-story structure, the use of a barrier on the 5th floor decreases the roof by 64%, and the position of the damper on the third floor leads to a 26% decrease in the structure's roof.