فهرست مطالب سهیل مجید زمانی

It is clear that steel structures are severely vulnerable to fire since the yield strength and the elastic modulus of the steel decease when the temperature increases, causing a reduction in the load-bearing capacity of the steel member. There are different methods for a steel element to reach required fire resistance rating. One of the most current methods in the world is the use of spray-applied mineral fire protective coatings. It is obvious that after a severe earthquake, the probability of the occurrence of the fire is high, e.g., because of the rupture of gas pipes. Unfortunately, there are not enough research pieces and reports on the performance of these coatings during an earthquake. However, we know that during a severe earthquake, the structure of the building will sustain significant deformations and it can cause the damage and delamination of the installed fire protective coating. Therefore, in this research, the post-earthquake fire performance of a mineral based spray-applied fire protection coating was studied. The type of this fire protection coating was cement based. Different application details of this mineral based spray-applied coating including coating thicknesses and reinforcing steel mesh details were investigated. First, four fire protected steel columns were subjected to cyclic lateral load tests. The type of the connection of these columns was a stiffened extended end-plate moment connection. This connection type was used for special steel moment frames. The thickness of the fire protection coating for steel specimens was determined for fire resistance rating of three hours. Then, these columns together with two reference columns were subjected to fire resistance tests to make a comparison between results. By using the qualitative and quantitative results of these tests, the type and amount of seismic damage of fire protection coating were determined in earthquakes with two different intensities. Also, it became clear that reinforcing the fire protective coating with a steel mesh in the region of formation of seismic plastic hinge in a steel element could reduce the seismic damage of the coating sufficiently.

This paper presents an experimental study of steel plate shear wall in the concrete moment frame. This study was based on the idea of using steel plate shear walls in precast concrete structures. The steel plate shear wall was bolted to the embedded plates in concrete boundary elements. These plates were embedded at specified intervals, and friction connection was used for the bolted connections. Semi-static cyclic loading was applied to three different specimens according to ACI T1.1-01 code. Lateral load was applied to the top of specimens. The formation of tension field and buckling waves expressed the required behavior of steel shear walls and, also, good performance of connection scheme. In order to illustrate the effects of adding steel shear plate wall to a concrete frame, one of the specimens was considered to be a bare frame. The results showed the placing of steel shear plate wall in the concrete frame, multiplied loading capacity, initial stiffness, dissipated energy, and equivalent damping of the bare frame by three, eight, twelve, and four, respectively. Horizontal and vertical stiffeners decreased the effects of openings. As diagonal opening with horizontal and vertical stiffeners kept initial stiffness the same and increased dissipated energy and equivalent damping by about 15\%; however, the lateral capacity decreased by 7\%. The results of the strain gauge showed that yielding initiated at a 0.4\% drift level. For the simple steel plate shear wall, the yielding started from corners; for the specimen with openings and stiffeners, it started from the bottom solid panel connected to beam and, also, edges of openings. The stress intensity of the bottom solid panel was more than the rest. Moreover, the steel plate initiated tearing at a drift level of 1.75\%. According to the strain gauge results, embedded corners plates were critical; however, all of them remained elastic. Moreover, it could be said that dissipated energy was obtained from steel plate shear wall. Small bending and shear cracks occurred at the beam-column connection. All of the specimens failed given hinge supports of columns.

In this paper effects of the placement of various stiffeners and opening on the interaction behavior of steel plate shear walls and precast concrete frame, has been investigated. Steel plate shear walls has been bolted to concrete frame, by use of embedded plate in boundary concrete elements. Push over and dynamic analysis under seven earthquake acceleration in ABAQUS software, was done.
The results showed that the proposed connection, by keeping up its stability and strength, showed appropriate function in the route of load bearing of shear wall. Also it was observed that adding steel plate shear wall to concrete frame increased initial stiffness, base shear and dissipated energy 4, 4.3 and 340 times, respectively. The sample with opening in diagonal line and horizontal and vertical stiffeners, had maximum dissipated energy (22% increased). This sample showed the maximum relative displacement (increased 2 times) and minimum base shear force (decreased by 10%). Adding horizontal and vertical stiffeners to simple sample, increased dissipated energy by 16% while, the sample with diagonal stiffeners decreased dissipated energy by 25%. This model showed the minimum relative displacement (decreased by 15%) and maximum base shear force (increased by 7%). Placing the opening at the middle of sides in this model, increased dissipated energy by 35%.

The extent of masonry structures and their weaknesses against earthquakes will increase the need for research on new ways of seismic rehabilitation of these structures. Recently, in addition to conventional techniques such as Mesh, Shotcrete, and FRP, new materials such as ECC materials have been considered by the researchers to retrofit the masonry walls. The composite materials of cement base, which is one of the types of cement base materials, due to the presence of fibers in the matrix, has a significantly different tensile strain capacity than that of conventional concrete, so that the range of this parameter for a typical mortar is 0.015%, and for composite materials of ECC is from 0.5 up to 6%. In the present study, the effect of these materials on the performance of the bearing masonry walls with in-plane failure modes including the diagonal tension mode (brittle mode) and the bed-joint sliding mode (the ductile mode) were investigated. The results of the research are based on the numerical method. ABAQUS software was used for numerical modeling. Due to validate the model, the available laboratory information of as-built masonry walls has been used. The as-built masonry walls are half scale. The wall dimensions for diagonal tension mode and bed-joint sliding mode were 1900x1400x110 and 2700x1400x160 mm, respectively. The gravity load of the wall was 0.1 MP. The walls strengthened with 20 mm ECC layers on one and both sides. In one case, ECC layers were joint to the foundation and in other case were not. A change in failure mode of strengthened walls (brittle to ductile) and hardening behavior were the main achievement of this research. If the connection between ECC layers and the foundation is absent, the failure mode of strengthened walls will be toe-crushing and rocking mode. If the connection between ECC layers and the foundation is present, the failure mode of strengthened walls will be toe-crushing and bed-joint sliding mode. Other obtained results showed an effective increase in strength and dissipated energy. The extent of this increase depends on how ECC layer is connected to the foundation. If there is no connection between ECC layers and the foundation, the strength and dissipated energy of walls with diagonal tension failure mode for one-side and both-sides ECC layers will be 2.3 and 3 times, respectively, in comparison with those of as-built masonry walls. Whereas for the bed-joint sliding mode, the extent of wall strength and dissipated energy is 1.4 and 1.8. according to the obtained results and comparing the properties of the wall strengthened by one-side and both- sides ECC layers, a significant difference was not observed, especially in bed-joint sliding mode. Appositively, if there is a connection between ECC layers and the foundation, the strength of walls for one-side and both-sides ECC layers will be 3.5 and 6 times, respectively, in comparison with those of as-built masonry walls. Whereas the dissipated energy of walls will be 3 and 4.5 times. Based on these results, if the ECC layers and the wall foundation are connected, the capacity of strengthened walls will be optimized.

In order to develop the underground structures such as subways, metro tunnels and other buried facilities in big cities, the dynamic interaction of these structures and their environment should be considered. In this study, all metro lines in Tehran are investigated and the 7th line with 28 km long and its environmental conditions in all length have been used as a case study. This line is selected because it passes through all kinds of geotechnical alluvium and also the plan and profile of this line are suitable for interaction with the buildings. A numerical method in this study was analyzed with finite difference code, FLAC, in dynamic cases. The models are performed for 8, 10,12,13,15 and 20 meter overburden and three different alluviums are used.
In dynamic interactions, previous studies showed high amplification of displacement in the vicinity of the tunnel in the surface. The parameter of acceleration is also investigated in some physical model tests. Both acceleration and attenuation of acceleration are reported in different locations and under the different seismic motions. For choosing the critical sections in selected line, the buildings with overburden less than 20 m and the maximum surface distance up to 5D are selected. In this study, two conditions of problem such as free-field, and tunnel field are analyzed. In tunnel-filed models, results show that the presence of tunnel can increase the surface acceleration up to 33% in initial part of line with 8 m overburden. This result is accrued under Chi Chi earthquake with the dominant frequency of 1.68. This increment of acceleration in critical cases can change the design acceleration of the building to 0.46 g instead of 0.35 g that is proposed by Iranian Code. By considering the results of all cases, it can be seen that the most effective case happened when the dominant frequency of motion is so close to the natural frequency of medium. The frequency content of medium is predicted by 1D propagation of wave with equivalent linear method in frequency content. The region between 0.5D to 1.5D from the center of the tunnel on the surface is most affected by the interaction. The effect of overburden of tunnel is also studied that shows that the deeper tunnel has less effect on surface but the influence zone on surface is greater. Both amplification and attenuation happened in the models for acceleration of the surface. The output data show that the variation of acceleration in surface depends strongly on the frequency content of input motion, the surface distance from axis of the tunnel and overburden of the tunnel. The most important factor that can describe the behavior of the surface is the variation of wave propagation around the tunnel. The presence of the tunnel under SH wave based on the mode of deformation can amplify the motions around the tunnel and not top of it in the surface. The tunnel in the medium can also prevent the propagation of waves to top of it and this may cause attenuation of motion. The color contour of the acceleration distribution around the tunnel and near of the surface during the dynamic analysis of model can better describe these phenomena.