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List of Articles
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Open Access Article
1 - A Study of the (Behavior of the) Isolated Bridges Using Elastomeric Isolaters Located Near the Faults
Rasol Bageri majid bargiyanABSTRACT The present paper is a study of the (Behavior of the) elastomeric bearing isolated bridges located near the faults. The earthquakes near the faults have high frequency and narrow bandwidth. Such characteristics cause the st MoreABSTRACT The present paper is a study of the (Behavior of the) elastomeric bearing isolated bridges located near the faults. The earthquakes near the faults have high frequency and narrow bandwidth. Such characteristics cause the strikingly high energy released due to production acceleration happening at the initial stage of the earthquakes to be imposed on the system. The present research undertakes to study the effects of the forces resulted by such type of earthquakes on the bridges. For this purpose, a three span highway bridge being of 60 meters length, for which were applied three types of lead rubber isolators in pursuant to the regulation envisaged in ASHTO standard, was designed. Using SAP2000, a 10.1 version was designed and the same was modeled in base-isolated and non-isolated modes. Considering the effect of three seismic recorders near the fault along longitudinal and latitudinal directions as well as in (YZ and XZ) directions, a nonlinear time history analysis was performed. The study of the behavior and load shift curves of the lead rubber isolators showed that initial strains and yield strength of such isolators cause significant reduction of base shear and bending moment in the bridge under study. Furthermore, simultaneous considering of the vertical and horizontal component of the earthquake in X and Y directions in the analysis showed increase compress or tension forces in column. These results show the shortcomings of the provisions recommended by, as instance, NEHRP and IBC about the isolated bridges in not considering the vertical effect of the earthquake. Such an effect should be taken into consideration as is the case with the non-isolated bridges. Manuscript profile -
Open Access Article
2 - Punching Shear in Fat Slabs and Suitable Methods to Prevent Shear Failure in Slabs
javad ezati arasto ArmaganiABSTRACT In the design of flat plate structures, special attention must be paid to the connection between the slab and the supporting columns. Despite extensive studies and improvement of codes in this subject, also there are problems about eva MoreABSTRACT In the design of flat plate structures, special attention must be paid to the connection between the slab and the supporting columns. Despite extensive studies and improvement of codes in this subject, also there are problems about evaluation of flat slab systems. In this paper punching shear in flat RC slabs is evaluated. Therefore the connections are retrofitted against punching shear, such as studs and column head. It is noted that parametric study is provided by ANSYS software. Finally results of Finite Element Method are evaluated. Manuscript profile -
Open Access Article
3 - Investigation of the Bond - Slip Effect on Cracking of RC Panel Using Lattice Model
Hamide shojaefar Masoud farzamABSTRACT The present paper studiesthree bond-slip models (CEB-FIP, Harajli and Farra) based on thefindings of previous experimental studies in order to investigate the influence of bond-slip on crack spacing and crack propagation in RC MoreABSTRACT The present paper studiesthree bond-slip models (CEB-FIP, Harajli and Farra) based on thefindings of previous experimental studies in order to investigate the influence of bond-slip on crack spacing and crack propagation in RC panel. For this purpose, the RC panel is modeled using a lattice type numerical model in ABAQUS software, in which the cracking process is represented by the damage of the concrete bar elements. The lattice models are proposed based on an improved cracking criterion, which is derived from fracture mechanics principles. Concrete and steel are combined based on a model of the interaction (bond-link) through bond-slip in order to describe the behavior of the composite reinforced concrete material. The results of this analysis showed that the effects of diverse bond-slip models on crack spacing, crack propagation and damage localization are significant. Manuscript profile -
Open Access Article
4 - Numerical and Experimental Investigation of Multi-Perforated Steel Shear Wall Under Cyclic Loading
Ali sahebjam Hossein shokatiABSTRACT Steel Shear Walls are a lateral resistance system in frames that has attracted many researchers’ attention owing to advantages such as appropriate ductility, high stiffness, significant shear strength and energy absorption. Since MoreABSTRACT Steel Shear Walls are a lateral resistance system in frames that has attracted many researchers’ attention owing to advantages such as appropriate ductility, high stiffness, significant shear strength and energy absorption. Since the early 1980s, when key researches on unstiffened Steel Shear Wall (SPSW) were under considerations, researchers were continously trying to improve the performance and efficiency of this system. One of these efforts was the creation of the opening in infill plate. Studies on perforated-SPSW began in the early 1990s by the experiments of Sabouri and Roberts. Recently a perforated-SPSW which having some circular openings was presented and examined by the researchers of Buffalo University. In addition to a system for passing the utility through the infill plate, this kind of opening is useful when a required thinner plate is not available, so it can be possible to substitute a proper multi-perforated Steel Shear Wall with a solid plate. This paper presents results of a research on the effect of multi openings on the performance of SPSW. Beside the experimental investigation a numerical study was conducted using the well-known ABAQUS finite element program was conduvted. Eventually the results of numerical and experimental studies were compared with the Plastic analysis’ conclusion. Results show a good agreement between experimental and numerical hysteresis and envelop curves. Furthermore, the Plastic analysis reduction factors seem to be conservative. Manuscript profile -
Open Access Article
5 - Numerical Evaluation of Columns’ Uplift in Bracing Structures
Abozar saleh seyadmehdi zahrayiABSTRACT One of the forces occurring during an earthquake is the tensile force that arise in the columns. This phenomenon is called ‘uplift’. It causes damage in column, base plate and anchor bolts. In the absence of app MoreABSTRACT One of the forces occurring during an earthquake is the tensile force that arise in the columns. This phenomenon is called ‘uplift’. It causes damage in column, base plate and anchor bolts. In the absence of appropriate control it may cause the building to collaps. Knowing the reasons which lead to such phonomenon will clarify the point that such phonmenon needs to be controlled. The present study has tried to offer solutions by which the uplift in columns can bereduced. This study has tried to by offering solutions the uplift in columns is reduced. To do so, the numerical models for two buildings were applied in which the location of the braced were changed and the number of brace columns were increased hoping to reduce the uplift strength. For each building, a separate model was built. In the models the proposed ways to reduce uplift were applied. Both EBF and CBF types of the braces were assessed. The numerical results obtained from the study indicate that using the single brace at the corners of the building, aiming to neutralize the uplift does not seem to be appropriate and that even the existence of an additional intermediate frame braced for further support might be needed. The present study showed that the increase in the number of span bracing in different places (situations) are effective in reducing the uplift more than 50%. Also, CBF in lateral columns and EBF for intermediate columns are better ways to reduce uplift, and that different numerical results according to the location of the column in plane. Manuscript profile -
Open Access Article
6 - Numerical Study of the Position and Dimensions of the Openings on the Seismic Ductility of the Reinforced Concrete Slab - Column Connections Having Flexural Reinforcing and Shear Bolts
Nasibe motazaker mohamadali lotfolahiyaginABSTRACT Concrete slabs are of the main components of the concrete structures. Implementing flat slab is more simple and economic than other ones owing to it’s ease of formatting. Furthermore, the flat MoreABSTRACT Concrete slabs are of the main components of the concrete structures. Implementing flat slab is more simple and economic than other ones owing to it’s ease of formatting. Furthermore, the flat slabs mostly utilized in the buildings with relatively irregular plans of flat slab- column structures. Unfortunately, the typical structures are ready to punching are prone to shear failure, but such shear brittle failure can be controlled by reinforcing the shear. Shear bolts is a shear strengthening method the influence of which on the slabs has been investigated in the present study. In practical situations, it is often necessary to create openings in slab to allow electrical, water or air conditioning ducts to go through floors. The existence of openings and their form along with their dimensions and slab-column connections impact the strength and ductility of the slabs. These specimens were placed under vertical load and cyclic lateral loads. The vertical load for each specimen was kept and cyclic lateral load increased. When the peak tension created, displacement in different points of slab and ductility were compared among different specimens. The analysis results show that shear bolts can increase lateral peak load resisting capacity, the lateral drift capacity at peak load, and also the ductility of the slab-column connections. Shear bolts also change the failure mode of the slab-column connections. Shear bolts capacity of the slab resist the lateral loads increases. The square opening dimensions are smaller better and circular opening more ductility to square opening one with same space. Manuscript profile -
Open Access Article
7 - Collapse Behavior Modification of Double Layer Barrel Vault Space Structures Using Force Limiting Devices
mehdi darvish hashemi mihammadreza sheydayi hadi zarintalaABSTRACT Space double-layer grids are the structures that are vulnerable to the progressive collapse phenomenon. So, some methods should be looked for space double-layer grids that change their collapse behav MoreABSTRACT Space double-layer grids are the structures that are vulnerable to the progressive collapse phenomenon. So, some methods should be looked for space double-layer grids that change their collapse behavior from brittle to a soft and ductile. In order to improve the space double-layer grids collapse behavior by using force limiting devices and also to avoid buckling, in compression members the structure element will be changed into the ductile ones. Hence space truss ductility can be done by force limiting devices. In the present study the effects of a number of force limiting devices on the progressive collapse behavior improvement of these structures have been studied. The present study determines the extent to which the limiting devices increase the ductility and load-carrying capacity variation of the double-layer space barrel vaults grids considering their number. Manuscript profile -
Open Access Article
8 - Determining the Optimum Position of Tuned Mass Damper with the Aim of Improving the Seismic Behavior of the Structures
Ahmad maleki mehdi Asadpour rasoul kodayadiABSTRACT The present paper attempts at investigating the position of tuned mass dampers in controlling the seismic behavior of the structures. Three buildings of 3, 7 and 15 stories with various natural periods, were designed acco MoreABSTRACT The present paper attempts at investigating the position of tuned mass dampers in controlling the seismic behavior of the structures. Three buildings of 3, 7 and 15 stories with various natural periods, were designed according to the allowed stress design method employing the ETABS. Designed sections and tuned mass dampers were modeled in opensees finite element analysis software, and finally subjected to several accelerograms. After conducting a number of dynamic analyses with various combinations of tuned mass dampers on the roof plan, the results were compared to other combinations of tuned mass damper location aiming to reduce the seismic response of the buildings. Optimum positions were selected according to the drift reduction criterion of the stories. Manuscript profile
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