Showing 21 results for Review Paper: Research
Mohsen Zahedi, Ali Zarei, Yahya Adineh Far,
Volume 1, Issue 1 (9-2017)
Abstract
The use of various additives including polymer additives to modify the properties of bitumen used in road pavement construction was crucial for researchers to use modified bitumen in the asphalt significantly increased pavement and operational life of them. Accordingly, in this study the effect of lignin derived from waste paper companies Chukka (Wood and Paper industries of Iran) on the performance of bitumen based on laboratory practices have been investigated. Lignin including natural polymers that in the paper production process must be separated from the texture of wood, so papermaking waste treatment plants to be found in large quantities. In this study different weight percentages of lignin polymer (3, 6, 9 and 12%) has been mixed with bitumen 60-70 Isfahan refinery and its impact on the various properties of bitumen was studied. Add this polymer improves the performance characteristics of the bitumen at high temperatures. Increasing lignin reduces the penetration grade, increase viscosity, increase rotary viscosity and softening point of bitumen. Also by increasing lignin, bitumen thermal sensitivity is reduced which indicates better performance is bitumen for road construction.
Mohammad Zarei, Farzad Akbari Nia, Ali Zarei, Hamed Azad Manesh, Mohsen Zahedi,
Volume 1, Issue 1 (9-2017)
Abstract
The main network of roads of the country is asphalted pavement. Finding a way to improve the technical properties of asphalt has attracted the attention of experts in recent years. Nanomaterials can be used to improve the technical properties of asphalt. On the other hand, fibrous materials can also be used to arm the asphalt mix. In this context and in this article by adding different percentages of nano-carbon black marshall experiments, analyze data and plot it was noticed that the addition of these additives increases the resistance of marshall and decrease of flow. On the other hand, resistance was increased by adding industrial polyester fibers to asphalt mixtures and in low percentages. Psychosocial rose as the percentage of industrial fiber polyester increased. Other results also changed. Economically, the results indicated that the use of fibers in general is preferable to nano-materials and its use in asphalt mix is recommended. Finally, by comparing the results, it was concluded that the blend containing black nanocarbon is more rigid than the mixture containing industrial polyester fibers, and it can be used in the regions with tropical weather and so much traffic and with more traffic and limited use.
Hamidreza Ashrafi, Peyman Beiranvand,
Volume 1, Issue 1 (9-2017)
Abstract
The effect of shape memory and super-elastic property are two exclusive features in shape memory alloys. In order to exploit the properties of shape memory effect, alloy needs to be heated but super-elastic property in these alloys will be proposed automatically in case suitable conditions. In case of using shape memory alloys as Longitudinal armatures in reinforced concrete structures considering them buried in concrete, exploitation of shape memory property will have its particular problems that these problems won’t happen about super-elastic property. Considering the high rate of strain capacity 3% to 8% in memory alloys with super-elastic behavior and the limitation of this capacity in concrete, conditions are necessary to be prepared in a way that memory alloy has the opportunity to propose super-elastic property. In this study, with simulating short-square reinforced concrete column experimental model in software ANSYS and in multi-level and increasing process, longitudinal armatures with shape memory alloy material will replace steel armatures with super-elastic behavior will be investigated with making shape memory alloy kind as variable (Copper and nickel-based alloys), the opportunity of super-elastic property emergence in these alloys and with playing the role of longitudinal armature in reinforced concrete column.
Korous Nekoufar, Maryam Saghafi, Mehrnaz Roozbahani,
Volume 1, Issue 2 (12-2017)
Abstract
The problem of erosion control and sedimentation in rivers has long been considered by humans. Every year a large number of bridges and flood in the river, at a time when they are most needed, are destroyed. One of the most effective agents of this destruction, scour around the base of the bridge, which creates a lot of human and financial losses. vanes submerged and non-submerged, structures that are at the bottom of the river with an angle to the main flow and in order to prevent the erosion of as rivers and screws and the base structure and morphology of the water and the river bed are correct. The secondary vortex structures cause's changes in the flow pattern of the river bottom sediment and erosion are the result of the transition. System, number, space, geometry and angle of the screen can be effective in the sediment of the front legs. Understanding the flow field plates can help engineers to better use them in rivers. So, in this thesis examined the effect of submerged vanes on the cylinder of the river has been using the software SSIIM and in this regard the placement of three vanes is studied in this research.
Behzad Haseli,
Volume 1, Issue 2 (12-2017)
Abstract
One of the influential factors in the response of the collapse of the bridge and the collage is its modeling. Seismic behavior analysis and bridging modeling are usually performed using simplifying assumptions. This simplification may lead to major changes in the prediction of bridle shaking behavior. In this research, the collapses in three general modes of modeling under the influence of earthquake records in the near field (due to the occurrence of the critical behavior of the bridge under the influence of near-field records in comparison with the far-field domains) were analyzed by nonlinear time-based analysis method in SAP 2000 software and the results in scenarios Different collage modeling is compared. Of noteworthy points in this study is the modeling of the shells as a wall base and the equivalent hardness calculation using static pressure and dynamic pressure of the back of the collar. The results of the analysis show that the modeling of the end nests in addition to the bridge displacement on other seismic parameters including axial force distribution, bending anchor, anchor response, and base cutting effect, in such a way that the results represent the maximum difference of 78% in the longitudinal displacement of the end nests , The 90% difference in the central axis force and the 82% difference in the bending relationship between the middle base based on the collage modeling is simplified, compared to the modeling of the collage as a roller. On the other hand, the results of studies in this study show that with the height of the back of the knoll in the range of 4 to 9 meters in height, with acceptable accuracy (the difference of responses is 29% to 13%), the collateral modeling can be replaced in the base form of Diviara Designed for modeling the shell according to the Caltrance directive (2013).
Farzin Farooghi,
Volume 1, Issue 2 (12-2017)
Abstract
In these studies, the effect of the load types on the stress and the deformation created in the hot-mix asphalt and its lifetime in different qualitative conditions of the surface contact of the layers has been investigated. For this purpose, we have used a set of rules in Iran and France codes. In Iran, the weight of the single-axle load 80 kN and in the French Code the weigh of the dual-axle load is 130 kN. Linear elastic method has been used in structural analysis and fatigue failure and rutting failure has been used to investigate the lifetime of structure. In these studies, the effect of the layer thickness and the two types of contact surface quality (adherence and Non-adherence) are considered. One of the most important results of this study is the significant increase in the vertical strain of the subbase course and horizontal strain of the base course due to single axel load compared to the dual axel load. Inappropriate quality of the layers has increased about 50% of the settlement in the pavement. Also, the effect of single axle load increased about 45% of structural settlement and decreasing of the base and surface courses thicknesse has increased about 30% seattlement in the pavement structure.
Fatemeh Rahimi,
Volume 1, Issue 2 (12-2017)
Abstract
At this paper, Non-linear FE models were used to stimulate strengthened deep beams with opening. Since the regulation, the analysis and designing of deep beams with opening in truss model has doubted, so FE models are the best option in terms of deep beam behavior. One web opening do not turbulent loads transfer path, whereas deep beams with 2 opening can clip the path of strut and decrease shear capacity. The comparison between experimental results and FE model with the ACI outcome, are representing accurate modeling in RC deep beams. Parametric analysis results indicate, when opening cut the strut path, shear strength will be limited. Specimens were retrofitted in perpendicular direction to plastic strain had the most shear strength.
Amin Faghrian, Akbar Ghanbari,
Volume 1, Issue 3 (3-2018)
Abstract
Explosion phenomenon has been most attractive subject for researchers during different era, from innovation of gunpowder to these days. The biggest of these researchers has been done during WW2. At last years, many terrorist attacks have been done by using explosion materials and bombs. Explosion is a chemical reaction; it finishes in some mill-second. During reaction a huge amount of energy release in the atmosphere and cause a pressure wave by high speed. Wave attacks building, impacts and forces them. In general, RC buildings have better reaction to explosion wave, because of their high mass. In this study, main goal is to observe the RC building under explosion load and finding ways to reduce or prevent damages. To model the RC building the ABAQUS Finite Element software has been used. For modeling it has been tried to make the model very close to the reality and to cover the proper details. The results show that distance has significant effect on reducing the explosion wave pressure and consequently on applied explosion loading.
Sina Rezaei, Saman Fathi Koche Tala, Ali Naseri,
Volume 2, Issue 1 (6-2018)
Abstract
In a general category, it is possible to divide the various irregular types of structures in height into two irregular geographic and nonlinear groups. In a geometric disorientation at elevation, the dimensions of the structure plan are significant at significant altitudes. In non-horizontal non-uniformity in height, sudden changes occur in the dynamic properties of the structure, including mass, stiffness and lateral resistance of the structure at height. Progressive breakdowns usually lead to a partial collapse of the entire structure, extending a primary damage within the structure, which is like a chain reaction. Studies on structural system failures In recent years, the importance of the phenomenon-failure phenomenon due to abnormal loading due to sudden damage, earthquake, explosion, earthquake, and so on. In this study, four steel structures with a dual-side duct frame, a special bending frame and specially designed 5, 10, 15, and 20 Story collimator brackets were designed in Etabs 2016 software. Then, using the US Department of Comprehensive Maintenance Manual and the method selection The alternative load transfer route, the well-known structures in OpenSEES software is modeled 3D and uses neonotope dynamic analysis to investigate the irregularities of the damping of the perpendicular system on the structural behavior of the seismic behavior in the progressive failure. After analyzing the results of the analysis, it was observed that the irregularity of the cutoff of the lateral load system reduced the structure and stability of the structure and reduced the structural strength against progressive failure.
Mehdi Atayi, Fereydoon Rezaei,
Volume 2, Issue 2 (9-2018)
Abstract
In an analysis of the seismic behavior of a structure, an excitation applied from the ground to the structure for the case where the structure relies heavily on the earth, it is the same stimulus that existed before the construction of the structure at that point of the earth, However, if the structure depends on the soft soil, significant changes will occur in the seismic input of the structure . Therefore, the structure with the surrounding soil will be in operation and will make changes in the base movements Consequently, taking into account the effects of interaction between the soil and structure can accurately increase the natural periodicity and thus reduce the coefficient of earthquake in design and consequently reduce costs. In this study, the resonant coefficients of displacement of fifteen flexural concrete frame with shear wall were resilient and non-reactive analysis. The studied frames are varied in the number of 5, 10, 15, 20, and 25 in 5 openings And the effect of the soil-structure interaction on the magnitude of the displacement coefficient and its comparison with the stationary foot state has been investigated. Each frame was modeled using nonlinear static analysis using the SAP2000 software . The Springer Wincher method has been used for substructure soil model. The results show that the magnitude of displacement coefficient in states with regard to the interaction of soil and structure is higher, regardless of the interaction of soil and structure.
Tina Jalalzadeh, Majid Barghian,
Volume 2, Issue 2 (9-2018)
Abstract
Earthquakes are the major cause of bridges destruction. It is obvious that the seismic ability of bridges and in general all transportation systems are very important in management of crises. For this reason, the seismic performance and behavior of particular types of bridges have been researched in this study. Skewed bridges are most popular and applicable in the design of highways and inter-city roads. Wherever roads cannot be continued straightly, bridges and in some cases skewed geometry of the bridges are practiced. The design of this kinds of bridges has become a normal practice within engineering communities in recent decades with emphasis on the construction of pre-stressed skewed box-girder bridges due to their characteristics and behavior. In this study three-span pre-stressed box-girder bridges with different skew angles were modeled using CSiBridge software. Seismic analysis was performed on the above-mentioned bridge with different skew angles and demand to capacity ratios for columns and internal forces of deck and columns were extracted from program to find out the general behavior of structure. Results indicate that increasing the skew angle of the bridge decreases the capacity ratio of the columns. An increasing trend is observed for the axial force of columns when increasing the skew angle in first bent columns while the converse is true for the second bent. Shear force in longitudinal direction of the bridge for columns tend to decrease while an increase is noticeable in the transversal direction in first column. Torsional moment in first bent rises in contrast to that of the second bent which declines. Bending moment about transversal axis decreases. For internal forces of deck with increase of skew angle the axial force increases, vertical shear force at beginning of bridge (obtuse corner) increase and at the end (acute angle) decrease. This force reduces on bents and increases in the middle of the bridge. The torsional moment of deck at beginning of bridge increases and at the end of bridge decrease, and at the middle increases. Transversal bending moment of beginning and the end of the bridge decrease and it is increased on bents and in the middle of bridge. Longitudinal bending moment at beginning, end and on bents of bridge decrease and on the middle of bridge increases.
Alireza Bidar, Mohammadali Mohandesi,
Volume 2, Issue 2 (9-2018)
Abstract
In this study the performance of concrete bridge has been under dynamic load near-fault earthquake in the area. According to available data showing the effects of the key uncertainties in earthquake ground motions near field fault, the performance of the bridge near the earthquake fault is investigated Two openings for three-dimensional modeling of a bridge taken in the application CSI Bridge And for evaluating the ability of a structure under earthquake near an earthquake fault area away from the fault, was assessed. Time history analysis based on models created under 7 record of past earthquakes on both far and near to a fault, was Through examining the record of near-fault earthquakes was observed that these earthquakes to produce a strong Tghyyrmkanhay far-fault earthquakes. Bridges isolated using seismic isolators, compared to far-fault earthquakes are a very good response this means By removing the bridges, the acceleration acting on the decks, cutting the base as well as the relative displacement uncut deck of the bridge reduced This is in response to the bridges near-fault earthquakes there. By examining the record of the earthquake was near an earthquake fault than the fault displacement away from strong earthquakes produce Which can enhance separation system in crisis situations, it is necessary to prevent this event The double system (FDGM) to modify call bridges that are used by the earthquake Change location near a fault code and the effect of taking away from the fault area will be more progressive So that for different ratios of distance to fault, whatever the value of this ratio is less, shift more and the maximum cutting force up to the bridge piers will be.
Mohammad Gholami, Ehsan Vaziri,
Volume 2, Issue 3 (12-2018)
Abstract
In the event of an earthquake occurring in steel Frames structures, if the lateral load-resisting system is a moment frame structure, these beams will dissipation of energy and developed plastic hinge in the beam, but this requires a strong connection that must be made in the design of the structure. A zone of beam and column connection exposed to flexural and shear stresses. This zone is considered as a sensitive area of the bending frame; if this area does not do its job properly, the transmission of force between the beam and the column is not properly executed and the structure will be damaged seriously. The reputable regulations of the world have considered certain criteria for this area and they are called connection springs. In this study, four models were designed to examine the force mechanism of this section and the behavior of this part is investigated. Contrary to expectation, a huge share of the cut is transmitted in scarves and underpants. In the next step, a model is designed to give the source of the connection a surrender. In this case, the shearing sheet transmits a negative cut into scarves and cufflinks.
Nariman Narimani, Davod Pourian,
Volume 2, Issue 3 (12-2018)
Abstract
Seismic separators with sufficient initial rigidity will resist the separating structure against lateral loads such as wind or mild earthquakes. Equipping the structure with the Seismic Separation System would result in the centralization of earthquake-induced displacement in the system, as well as a lack of influence on the horizontal component of the Earth's motion. In this research, the modeling of lead-coated rubber separators is compared with the SAP2000 software in two modular steel frame systems and X-axis steel bracing system. Using nonlinear static analyzes, their performance has been evaluated in structures 5 and 10 of the class. The results showed that the average steel moment frame systems with LRB have more energy than concentrically brace frame.
Behnam Olade, Mohammad Gholami,
Volume 2, Issue 4 (3-2019)
Abstract
The bending connections Beam to the Cruciform Column in Iran are increasing. Normal columns, such as columns I and H, have the ability to connect two Beams. Cruciform Columns the ability to connect 3,4 Beams. This requires a strong connection that should be considered in the design of steel structures. One of the members of the connecting Panel Zone. In the design Codes, the relationship between the yield point and final point of the panel zone in the H columns was presented.The purpose of this study is to investigate the behavior and strength of panel zone in cruciform columns. For this purpose, the modeling has been used by ABAQUS software. In the first step, numerical modeling has been confirmed with laboratory verification. In the second step, by designing and modeling 20 numerical models, the strength of the panel zone is investigated. According to the results of models, it was found that for the Cruciform Column it is not possible to use the relations provided for H columns. As a result, there are relationships for determining the strength of panel zone in cruciform columns in an elastic and non-elastic state, provided that the rotation of the coupling fence is not quadrupled above the elastic limit.
Alireza Mortezayi, Sohrab Sadrayi,
Volume 2, Issue 4 (3-2019)
Abstract
The effect of severe earthquake movement time is one of the most important and ambiguous parameters in the structures. This parameter along with the magnitude and distance from the fault are the determinant factors in the failure of the structures and the study of the factors affecting the performance of this index on the structure seems necessary. In this research, we tried to study the past research to conduct the right research, and to clarify the hidden aspects of work that can lead to the performance of the structures until complete failure.
Shamsedin Hashemi, Reza Kiani Zadegan,
Volume 2, Issue 4 (3-2019)
Abstract
In this paper, the reinforced concrete frames with concrete shear walls are studied from the perspective of the performance-based design method. The shear wall is modeled as an equivalent column with a rigid beam on its top and its hinges are assigned to the equivalent column depending on the moment or the shear governing the behavior of the wall. For this purpose, two-dimensional models of three reinforced concrete frames with concrete shear walls are created. Models with 5, 10 and 15 floors are created to represent the low-rise, mid-rise and high-rise buildings. The models are investigated using the traditional pushover analysis in SAP software. Moreover, adaptive analyses including force-based adaptive pushover (FAP) and displacement-based adaptive pushover (DAP) are conducted using SEISMO STRUCT software.
To investigate the validity, the results of the pushover analysis are compared with the results of nonlinear time history analysis. For nonlinear time history analysis, 7 far field earthquake records which were recorded from soils with shear wave velocities between 175 to 375 meters per second at a distance of approximately 20 km far from the epicenter of the earthquakes are selected.
The results of these investigations show that, for the high-rise and mid-rise buildings, the traditional pushover analysis results in more displacement and stresses in comparison to the nonlinear time history analysis. Also, the first mode pattern causes more drift than the other patterns. Adaptive analysis which was thought to be based on a stronger logic resulted in more inaccurate responses compared to the traditional pushover analysis. Significantly, DAP analysis failed to meet expectations. The results also show that structures with shear walls and matching the correct design based on linear analysis are resistant to phase shift and do not collapse. Another important result is that the buildings designed based on linear analysis of the Iran 2800 code perform well for non-linear analysis and practically never approach life safety, which is a performance level of Iran 2800 code. This study demonstrates that the frame-shear wall system is very effective in reducing the level of performance and is able to hold a building at low performance levels.
Mahdi Salemi, Mohammad Gholami,
Volume 2, Issue 4 (3-2019)
Abstract
Shear walls are one of the most lateral- forces resistant systems which have been nicknamed "shear walls" due to their high shear force absorption. Bending deformation of these structures is noticeable which results in great tensions at the foot of the wall. These walls are divided into two groups of reinforced concrete and steel walls and their behavior are different from each other. Reinforced concrete shear walls have high out- of- plane stiffness which prevents them from buckling but steel shear walls have low out- of- plane stiffness and their behavior is affected by diagonal traction fields which results in shear capacity reduction. In order to prevent these walls from buckling, steel plates are connected to concrete panels by means of shear studs. Coupling of steel shear walls changes their behavior and steel plates reach their ultimate capacity. Therefore, in this study, nonlinear static behavior and seismic parameters of composite shear walls system have been investigated. At the beginning of the research, a sample of the laboratory model has been verified to ensure the modeling of the composite shear wall in the nonlinear behavior range. In the next study, a double-skinned steel frame system and five-story compound shear walls were designed in a panel based on a reasonable behavior coefficient. In ABAQUS software, non-linear static modeling and analysis was performed and seismic parameters This system has been calculated for its behavior coefficient and shape. The results of the seismic parameters derived from this model are in good agreement with previous studies.
Mahdi Salemi, Mohammad Gholami,
Volume 3, Issue 1 (6-2019)
Abstract
According to researches and experiments conducted by researchers, it is accepted that shear walls have significant structural parameters such as lateral stiffness, shear capacity and energy absorption. These walls are known for their shear force due to the shear force absorption, while flexural deformations occur, and stresses from the bending anchor at their feet are remarkable. Now, if we connect two adjacent and separate shear walls together with very difficult towed beams, the strength and behavioral properties of these walls will change greatly. So, to clarify this, at the beginning of the present study, the relationships between the elastic analysis of the system are reviewed in a continuous method. In the next study, a 10-story coupled shear wall system is compared with the results of ABAQUS software based on the continuous method of elastic analysis. According to studies, the lateral displacement in the system of the coupled shear walls is increased and the lateral stiffness decreases. Also, the bending anchor in the shear walls is sharply reduced relative to the uncoupled shear walls, but the shear force does not change in each of the walls, but very large shear force are formed in the coupled beams, which are Axial force is transmitted to the walls. In general, the presence of coupled beams in the system of uncoupled shear walls significantly reduces the stress at the foot of the walls and makes the lateral deformations in the walls to be flexed to the shear.
Ahmad Maleki, Babak Baradar Ayari Khosroshahi,
Volume 3, Issue 1 (6-2019)
Abstract
In today's world, with the rapid advancement of science and technology, new materials are emerging every day, in which alloys of memory are a form of these materials. Since the use of the frame system with conventional bracing is not responsive to structural requirements due to limitations such as low wear ability, buckling bracing in the pressure and reducing load capacity, so the use of this type of alloy in brackets can be a breakthrough. In this research, the effect of braces with intelligent memory alloys on energy dissipation and steel frame formation is investigated by modeling in ABAQUS finite element software. The braiding function is modeled in several modes: braiding consisting of steel, memory alloy, memory alloy and steel along the length and cross section of the bracket with different sizes in the form of 7 numerical models in Abaqus software and their results are compared. In two models, one of which has only memory-alloy materials and the other steel materials, the analysis of the results showed that the final weight of the braiding material is about 16% more than the bracelet with alloys of memory. Also, the initial hardness and maximum stress and energy consumption are higher than the steel model. In models that use a combination of two compositions of memory alloy and steel in a cross-sectional curtain (in different ratios), reducing the steel's percentage has a very small effect on reducing the final load and the energy consumption of the bracing. The results showed that the initial stiffness and energy consumption of the two models are approximately equal to those of the curtain that had 50% of the cross-sectional length and the bracelet length of the steel and the rest of the memory alloy. But the final load and the stress of a model in which two materials in the cross-sectional area are 18 KN and 115 Mpa, respectively.
