Sharif Digital Repository

One of the most common failure modes of structures in earthquakes is soft story failure which causes by discontinuity of lateral force resisting elements like braces. so the ground floor acts as a soft floor. In this case columns are imposed to large deformation and plastic hinges are formed at top and bottom of the columns. This case is named as story mechanism (severe drift of the story). In most of this case building collapsed or going to collapse. To resolve this problem, different solutions are presented. One of the strategies under section (2-10) 2800 code is increase of designed load in columns of the soft floor. This measure cause to Significant increases in the sections of the... 

Controlling the structures under seismic excitations is a great challenge in the earthquake engineering. In this regard, bracing systems have been presented and applied to provide additional rigidity for the structures. However, conventional bracing systems are buckled under compressive forces. In this research ribbed bracing system (RBS) is proposed to deal with the buckling problem of conventional bracings. Full capacity of RBS is used under cyclic loading. Ribbed bracing system is constructed by adding a supplement part with a ribbed mechanism to the conventional bracing systems. As the supplement part is locked when the bracing is under tensile forces, the bracing system can absorb... 

In this research, an innovative system, called ribbed bracing system (RBS), proposed to deal with poor performance and deficiency of brace buckling under compression loads. RBS is an additional component added to common brace system which prevents the buckling problem of conventional bracing systems. By applying tensile load, the ribs lock together and the system starts enduring tension. Since the compressive force begins, ribs slide on each other and the system endures only a trivial force. Two kinds of RBS mechanism are introduced: completely-closed RBS (CC-RBS) and self-centering RBS (SC-RBS). In the former mechanism, the length of the brace is reduced by applying compression loads; while... 

As a result of numerous earthquakes happened in recent decades, widespread failures were observed in conventional braced frames, which were mostly created due to buckling of the braces under compression. To find a solution to overcome this problem, Ribbed Bracing System (RBS) was developed by Golafshani et al. in 2004. In this study, continuing the experimental investigation and considering the previous outcomes, the RBS bracing was redesigned based on some modifications. Then, two half-scale RBS braces with pinned frames were constructed and tested under cyclic loading. RBS systems were utilized in two options, CC-RBS and SC-RBS, in X configuration, the first of which was constantly... 

Placement of control and bracing systems in a structure is one of the most important factors affecting the effectiveness of the system in reducing responses to earthquakes. In other words, a control system with a proven effectiveness in earthquake does not reduce the structure responses unless used with proper placement. The performance of Ribbed Bracing System (RBS) in enhancing seismic response of structures, especially in preventing the buckling of bracing under compression and removing residual displacements, is approved by analytical and experimental studies, but optimal placement of such systems in structures has not been studied yet. Hence, in this research the optimal placement... 

Among various impacts on environment, the noise problem arising from the expansion of technology has been an important factor, especially in recent years. The noise level in the automotive industry is also considered as a desirability coefficient. One of the most important factors which are causing noise in the vehicle is an automotive gearbox system. The gearbox is major component of automotive powertrain. In the gearbox system, gears pairs generates mechanical noises in the gearbox that transfer to other parts of the car by gearbox housing. Therefore, reduction and isolation this vibration in gearbox housing have crucial role in reducing the noise level of the vehicle. The aim of this... 

In order to improve the performance of structures against earthquake loads, engineers believe that both minimizing the rigidity and maximizing the ductility; can lead to minimization of the energy input of the structure. However, the minimized energy shall be depreciated as much as possible in different stories so that the damage to the main and Irreplaceable structural members remains as low as possible.
Steel with high strength and ductility is relatively an ideal material for this purpose; however, the ductility level of this material is much higher than that is normally in use. In order to have a better utilization of the steel ductility, RBS (Ribbed Bracing System) was invented in... 

Offshore platforms are one of the most important structures in oil-rich countries, so that their economic benefit makes it very expensive to stop their usage. Therefore, it is essential that their performance is not disrupted by earthquake or the tidal waves made by severe storms. The new high performance semi-active bracing system, developed by Golafshani et al, is capable of removing the permanent drift of stories at the end of excitation and concentrating structural damage in braces. In the conventional bracing systems it is assumed that the braces buckle under little compressive forces; but in this new presented completely tensile-ribbed bracing system (RBS), buckling of compressive... 

Ribbed Bracing System (RBS) is an innovative structural system designed to eliminate the buckling of braces and enhance the behavior of structures under seismic loads. In this study, a collaborative performance of two RBS devices bracing a frame was assessed numerically and experimentally. In the numerical phase, the collaboration of ribbed braces at various stages of reversal loading was elaborated mathematically and was used for representing the system using finite element modeling. In the next phase, the numerically observed behavior was validated experimentally by conducting cyclic quasi-static tests of the proposed configurations. Two alternative RBS configurations—called Completely...