Abstract:In some cases, tall buildings are located in geotechnically unsuitable places, due to their high ratio of height to width; there is risk of uplift and other effects such as overturning and reduction structure serviceability during earthquake. This research is aimed to evaluate the effect of SoilStructure Interaction (SSI) on seismic behavior of two adjacent 32 story buildings such as time period, base shear and displacements. The interaction effects are investigated for variable distance between the two buildings. Three types of soil such as soft clay, sandy gravel and compacted sandy gravel are considered for this study. The result obtained that the interaction effect increases time period of both buildings base shear and lateral displacement of the structures increases.

Milad tower is located in Tehran, Iran, and is a 436‐m telecommunication tower ranked as the fourth tallest structure in the world. Because of its specific use and also because of highly sensitive communication devices installed on the tower, nonlinear deformations under future severe winds and earthquakes should be studied. In this paper, a comprehensive study is carried out to investigate the effect of wind on this tower. The techniques of computational fluid dynamics, such as large eddy simulation (LES), Reynolds Averaged Navier–Stokes Equations (RANS) model and so on, were adopted in this study to predict wind loads on and wind flows around the building. The calculated results are compared with those of wind tunnel test. It was found through the comparison that the LES with a dynamic subgrid‐scale model can give satisfactory predictions for mean and dynamic wind loads on the specific structure of Milad tower, while the RANS model with modifications can yield encouraging results in most cases and has the advantage of providing rapid solutions. Furthermore, it was observed that typical features of the flow fields around such a surface‐mounted bluff body standing in atmospheric boundary layers can be captured numerically. Copyright © 2009 John Wiley & Sons, Ltd.

Recent structural collapses caused by fire have focused attention on research concerning fire safety in building design. Steel connections are an important component of any structural steel building as they provide links between the principal structural members. Considering the importance of this matter this paper describes a spring-stiffness model developed to predict the behavior of bolted angle connections bare-steel joints at elevated temperature. The joint components are considered as springs with predefined mechanical properties i.e. stiffness and strength. The elevated temperature joint's response can be predicted by assembling the stiffness of the components which are assumed to degrade with increasing temperature based on the recommendations presented in the design parameters code. Comparison of the results from the model with existing experimental data showed good agreement. The proposed model can be easily modified to describe the elevated temperature behavior of other types of joint as well as joints under large rotations.

SUMMARY The behavior of bolted angle connections under the combination of shear and tensile forces is studied in this paper to simulate the force applied on a connection in a real fire. First, ansys is used to develop a 3D model of these connections. These models are analyzed in a similar condition to experimental tests, ignoring the tensile force, and the results are compared with those of the experimental tests. Having assured of the accuracy, we studied the connection models in several conditions under the combination of shear and tensile forces. The results show that the strength of connection is rapidly decreased when the temperature is increased, and the decrease pattern of connection strength is similar to decrease pattern of bolts used in the connection. Moreover, investigation of strength reduction value of these connections by the increase of temperature under shear and tensile forces obviously shows that it is possible that the failure of steel frames at elevated temperatures occurs at the connections, and thus utilization of catenary action to enhance the fire resistance of structural steel beams requires investigation of the capacity of steel connections to resist the tying forces generated at the ends of the beams. Copyright © 2012 John Wiley & Sons, Ltd.