In this project attempt has been made to use straightening machine for extruded brass bars as a repairing machine to be evaluated as a conceptual design. At first, reasons for the existence of such machine have been stated and then its specifications, ease of making, ma More
In this project attempt has been made to use straightening machine for extruded brass bars as a repairing machine to be evaluated as a conceptual design. At first, reasons for the existence of such machine have been stated and then its specifications, ease of making, maintanance, operation and its high accuracy are discussed. In the initial stages of design, total dimentions of related parts with regard to design expectation and working condition are selected which gave the total size and dimension of the machine. Later, the machine was designed into two parts, that is stimulant machine and supports. Also, the material for parts with regard to its application for the machine was chosen.
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Today, the need to design and implement structures with less vulnerability and damage, and easier repair after an earthquake is essential. Traditional seismically resistant lateral systems can cause serious damage to the structural system and the relative displacements More
Today, the need to design and implement structures with less vulnerability and damage, and easier repair after an earthquake is essential. Traditional seismically resistant lateral systems can cause serious damage to the structural system and the relative displacements remaining in the structure make it very difficult and uneconomical to repair the structure after an earthquake. The utilize of rocking motion in the structure causes the destruction of destructive seismic effects including energy dissipation and improves the seismic behaviour. In this research, in order to investigate the effects of the rocking motion system on the seismic response of short and tall regular steel buildings, a five- and ten-story steel frames with special moment frame lateral bearing system according to the fourth edition of Standard 2800 and the latest editions of the sixth and tenth national building regulations are designed by Perform3D software. Seven earthquake records were selected and then these records were based on ASCE regulations scaled according to the spectrum of the 2800. By using nonlinear time history analysis, the seismic response of the studied building has been investigated in conditions with and without using a rocking motion system. The results of studies such as base shear, Relative displacement of floors, energy dissipation and lateral and vertical accelerations of the roof indicate that the use of rocking motion system in short and tall steel buildings can significantly improve the seismic response of the structure.
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Zipper bracing system is one of these types of braces. The zipper bracing members transfer the unbalanced tensile forces created in a floor to its upper floor, and this process continues until there is an increase in lateral load and causes the braces of the higher floo More
Zipper bracing system is one of these types of braces. The zipper bracing members transfer the unbalanced tensile forces created in a floor to its upper floor, and this process continues until there is an increase in lateral load and causes the braces of the higher floors to buckle. In this article, the dynamic behavior of the braced structure with zipper under the influence of earthquake records with rocking component and without rocking movement has been studied. SAP2000 software was used for modeling. Seven accelerometer pairs have been utilized for nonlinear dynamic analysis. The studied frames are 6-, 9- and 12- floors with a floor height of 3 meters. In all the studied models, the joint in the bracing part has been damaged. In this part, most of the damages have been at the level of continuous usability, and in the 9- and 12-story structures, the damage is a little wider and at the level of life safety performance. In the structures where rocking movement has been applied in the foundation part, it has caused the movement and shearing of the foundation of the structure to be reduced by 20 to 35 percent because it absorbs some of the earthquake force. Examining the results related to the displacement of the roof of the structure, it has been observed that the displacement of the roof in the structure with CBF bracing was about 10 to 25% less than the structure with zipper bracing.
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In this paper, a 15-story steel building was designed based on Iranian code No.2800 in order to study the effects of rocking systems on the seismic response of high-rise steel buildings. The selected accelerograms were related to the Chi Chi, Landers, Loma Prieta, North More
In this paper, a 15-story steel building was designed based on Iranian code No.2800 in order to study the effects of rocking systems on the seismic response of high-rise steel buildings. The selected accelerograms were related to the Chi Chi, Landers, Loma Prieta, Northridge, Parkfield, San Fernando and Tabas earthquakes which were selected and scaled according to Iranian Standard No. 2800. These accelerograms were related to the stations which were registered at the distance of 20 to 60 kilometers from the fault and did not have the near-fault earthquakes characteristics such as forward directivity and fling step and etc. Furthermore, the magnitude of all the selected earthquakes was between 6.5 and 7.5 Richter. Then, nonlinear time history analysis was used to investigate and compare the seismic response of the studied building in cases with and without using the rocking system. The results of studies (including base shear, drift, displacement of roof, acceleration of roof and etc.) indicated that using rocking system in the high-rise steel buildings could cause significantly reduce the seismic response of high-rise steel buildings.
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