Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
DEVELOPING FRAGILITY CURVES FOR REGULAR STEEL BUILDINGS WITH X-BRACING USING NONLINEAR TIME HI&zw
DEVELOPING FRAGILITY CURVES FOR REGULAR STEEL BUILDINGS WITH X-BRACING USING NONLINEAR TIME HI&zw
3
150
584
FA
M.
Hosseini
Structural Engineering Research CenterInter&z
M.
Mjd
Faculty of Technical and Engineering\nIslamic Az&zw
Journal Article
2008
10
12
Fragility curves are important in the seismic damage assessment of buildings. In this study, with the aim of damage evaluation at various levels of earthquake intensity, fragility curves have been developed for some sets of steel buildings; having Concentrically Braced Frames (CBFs) as their load bearing system. The buildings sets include a set of 2- by 4-bay and another set of 4- by 6-bay plans, having 3, 5, or 7 stories. The buildings have been assumed to be regular in both plan and elevation to avoid torsion effects. For developing the fragility curve, Nonlinear Time History Analyses have been used, by applying 42 different recorded accelerograms to each building, with various Peak Ground Acceleration (PGA) values and, also, different frequency contents. Two different damage indices, the values of story drifts and the amount of axial plastic deformation of bracing elements, have been used. The numerical results show that when PGA$>$0.5g, the variation of fragility curves is less than the variation corresponding to PGA$<$0.5g.The results also show that tthe second index is more reliable for developing the fragility curves of steel buildings with CBFs.
Fragility curves are important in the seismic damage assessment of buildings. In this study, with the aim of damage evaluation at various levels of earthquake intensity, fragility curves have been developed for some sets of steel buildings; having Concentrically Braced Frames (CBFs) as their load bearing system. The buildings sets include a set of 2- by 4-bay and another set of 4- by 6-bay plans, having 3, 5, or 7 stories. The buildings have been assumed to be regular in both plan and elevation to avoid torsion effects. For developing the fragility curve, Nonlinear Time History Analyses have been used, by applying 42 different recorded accelerograms to each building, with various Peak Ground Acceleration (PGA) values and, also, different frequency contents. Two different damage indices, the values of story drifts and the amount of axial plastic deformation of bracing elements, have been used. The numerical results show that when PGA$>$0.5g, the variation of fragility curves is less than the variation corresponding to PGA$<$0.5g.The results also show that tthe second index is more reliable for developing the fragility curves of steel buildings with CBFs.
https://sjce.journals.sharif.edu/article_584_f5deaeeae1538fb6c45901d524ee2f98.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
EVALUATION OF RETROFITTED STEEL BEAMS BY FIBER REINFORCED POLYMER
EVALUATION OF RETROFITTED STEEL BEAMS BY FIBER REINFORCED POLYMER
15
19
585
FA
A.
Rahae
Dept. of Civil and Environmental Engineering Ami&zw
0000-0002-9101-0794
H.
Ghaffari
Dept. of Civil and Environmental Engineering Ami&zw
Journal Article
2008
10
20
Regarding the vast and suitable application of fiber reinforced polymer (FRP) in the strengthening of concrete structures, the recent idea of using fiber reinforced polymer composites in steel structures has been formed and extended by doing experiments and extensive research. The aim of this present research is to study the strengthening of bending steel beams by composite plates and, also, the rate of increasing the length of the FRP plate on the performance of the strengthened beam. All beams are selected in 1 shape with a length of 2000 mm. So, 6 beams have been tested in this research; 2 beams strengthened with composite plates in the whole length, 2 beams strengthened only in the middle of their length and the other beams loaded without composite plates as the control beams. The retrofitted and control beams were tested under static loading, so, besides preparing the diagram of the force-distance, the yielding load of beams and the failure of composite plates are determined. To verify the results of the experiments, a beam was modeled by the existing finite element software and its force-displacement diagram was compared with the results of the experiment. According to the results, application of composite plates increases the bending capacity of steel beams. Moreover, force-distance diagrams indicate the desirable performance of strengthened beams.
Regarding the vast and suitable application of fiber reinforced polymer (FRP) in the strengthening of concrete structures, the recent idea of using fiber reinforced polymer composites in steel structures has been formed and extended by doing experiments and extensive research. The aim of this present research is to study the strengthening of bending steel beams by composite plates and, also, the rate of increasing the length of the FRP plate on the performance of the strengthened beam. All beams are selected in 1 shape with a length of 2000 mm. So, 6 beams have been tested in this research; 2 beams strengthened with composite plates in the whole length, 2 beams strengthened only in the middle of their length and the other beams loaded without composite plates as the control beams. The retrofitted and control beams were tested under static loading, so, besides preparing the diagram of the force-distance, the yielding load of beams and the failure of composite plates are determined. To verify the results of the experiments, a beam was modeled by the existing finite element software and its force-displacement diagram was compared with the results of the experiment. According to the results, application of composite plates increases the bending capacity of steel beams. Moreover, force-distance diagrams indicate the desirable performance of strengthened beams.
https://sjce.journals.sharif.edu/article_585_a9a1d5317a33ae8cef33961c34144f84.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
INTRODUCTION OF ROTATO-TRANSLATIONAL COLLAPSE MECHANISMS IN BEARING CAPACITY PROBLEMS
INTRODUCTION OF ROTATO-TRANSLATIONAL COLLAPSE MECHANISMS IN BEARING CAPACITY PROBLEMS
21
31
586
FA
F.
Askar
International Institute of Earthquake Engine&
N.
Ganjian
Faculty of Technical and Engineering Islamic Az&z
O.
Farzane
Dept. of Civil Engineering University of Tehran
Journal Article
2008
10
21
This paper proposes a new rotato-translational collapse mechanism consisting of three rigid blocks with both translational and rotational movements, based on the upper-bound limit analysis theorem. It is revealed that the rotational collapse mechanisms somewhat over- estimates the bearing capacity values of foundations, just as the translational collapse mechanisms. By applying the proposed mechanism to evaluate the bearing capacity of a strip footing subjected to combined loading, it became possible to improve the results of the bearing capacity analysis, particularly in constrained conditions. Comparisons are made with other analytical results to evaluate the ability of the proposed collapse mechanism and the correctness of solutions. Based on comparisons with known solutions, the method was generally found to predict the bearing capacity of foundations precisely. To specify the ability of the proposed mechanism, the bearing capacity of strip footings under combined loading over thin layer foundation soils is investigated.
This paper proposes a new rotato-translational collapse mechanism consisting of three rigid blocks with both translational and rotational movements, based on the upper-bound limit analysis theorem. It is revealed that the rotational collapse mechanisms somewhat over- estimates the bearing capacity values of foundations, just as the translational collapse mechanisms. By applying the proposed mechanism to evaluate the bearing capacity of a strip footing subjected to combined loading, it became possible to improve the results of the bearing capacity analysis, particularly in constrained conditions. Comparisons are made with other analytical results to evaluate the ability of the proposed collapse mechanism and the correctness of solutions. Based on comparisons with known solutions, the method was generally found to predict the bearing capacity of foundations precisely. To specify the ability of the proposed mechanism, the bearing capacity of strip footings under combined loading over thin layer foundation soils is investigated.
https://sjce.journals.sharif.edu/article_586_605ff764c617d3cd28dbbdd72be8f9a2.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
A STUDY OF EFFECTIVE FACTORS ON THE BEHAVIOURAL CHARACTERISTICS OF CLAYEY SANDS
A STUDY OF EFFECTIVE FACTORS ON THE BEHAVIOURAL CHARACTERISTICS OF CLAYEY SANDS
33
44
587
FA
O.
Naeemifar
Faculty of Engineering Tarbiat Modares Univer
S.S.
Yasrebi
Faculty of Engineering Tarbiat Modares Univer
Journal Article
2008
10
29
As, in recent years, liquefaction phenomena have occurred in sandy soils containing different amounts of clay content, it was concluded that, in addition to silty sands, clayey sands are also vulnerable to the liquefaction phenomenon. So, the urge for comprehensive study was aroused to cover the issue.In this paper, the effect of clay content and its plasticity properties on the behavioural characteristics of clayey sands under various density and confining pressure values has been investigated. To achieve the goal, about a hundred monotonic triaxial tests were performed on remolded specimens of sandy soil containing different clay content with different plasticity values. Based on the results, the latter factors affect peak strength, steady state strength and angle of internal friction, considerably. Furthermore, great results were obtained regarding the issue of whether clay content or plasticity property variations are more effective.
As, in recent years, liquefaction phenomena have occurred in sandy soils containing different amounts of clay content, it was concluded that, in addition to silty sands, clayey sands are also vulnerable to the liquefaction phenomenon. So, the urge for comprehensive study was aroused to cover the issue.In this paper, the effect of clay content and its plasticity properties on the behavioural characteristics of clayey sands under various density and confining pressure values has been investigated. To achieve the goal, about a hundred monotonic triaxial tests were performed on remolded specimens of sandy soil containing different clay content with different plasticity values. Based on the results, the latter factors affect peak strength, steady state strength and angle of internal friction, considerably. Furthermore, great results were obtained regarding the issue of whether clay content or plasticity property variations are more effective.
https://sjce.journals.sharif.edu/article_587_766ebcd59621e305170616ba3d3dac32.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
BEARING CAPACITY CALCULATION OF SHALLOW STRIP FOUNDATIONS ON REINFORCED SOILS
BEARING CAPACITY CALCULATION OF SHALLOW STRIP FOUNDATIONS ON REINFORCED SOILS
45
53
588
FA
M.
Shirdel
Faculty of Engineering Tarbiat Moallem Univer
A.
Ghanbari
Faculty of Engineering Tarbiat Moallem Univer
Journal Article
2008
11
01
A new analytical approach, based on the horizontal slices method, has been proposed for calculating the ultimate bearing capacity of shallow foundations on reinforced sandy soils. The equilibrium of forces and moments in hypothetical horizontal slices beneath the foundation has led to a new formulation consisting of 5N+1 equations and 5N+1 unknowns. With the aid of the suggested method, the ultimate bearing capacity has been calculated for strip foundations constructed on soils being reinforced with only one reinforcing element. A logarithmic spiral failure mechanism has been accepted, as proposed by several researchers. For the purpose of obtaining more accurate results, the geometrical properties of a failure surface have been determined by dividing the failure wedge into 3 zones and analyzing each ones related parameters. Using the elasticity theory, additional vertical stresses acting on slices are then calculated. Finally, the bearing capacity of a reinforced foundation has been studied under two different static and pseudo-static conditions. A comparison of results with experimental and analytical studies available in literature shows an acceptable agreement between this method and previous ones.
A new analytical approach, based on the horizontal slices method, has been proposed for calculating the ultimate bearing capacity of shallow foundations on reinforced sandy soils. The equilibrium of forces and moments in hypothetical horizontal slices beneath the foundation has led to a new formulation consisting of 5N+1 equations and 5N+1 unknowns. With the aid of the suggested method, the ultimate bearing capacity has been calculated for strip foundations constructed on soils being reinforced with only one reinforcing element. A logarithmic spiral failure mechanism has been accepted, as proposed by several researchers. For the purpose of obtaining more accurate results, the geometrical properties of a failure surface have been determined by dividing the failure wedge into 3 zones and analyzing each ones related parameters. Using the elasticity theory, additional vertical stresses acting on slices are then calculated. Finally, the bearing capacity of a reinforced foundation has been studied under two different static and pseudo-static conditions. A comparison of results with experimental and analytical studies available in literature shows an acceptable agreement between this method and previous ones.
https://sjce.journals.sharif.edu/article_588_daca41214b39c5dc66674d09081940f0.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
THE EFFECT OF BRACING PATTERN ON THE FRAGILITY CURVES OF REGULAR STEEL BUILDINGS WITH X-BRACING, USI&zwn
THE EFFECT OF BRACING PATTERN ON THE FRAGILITY CURVES OF REGULAR STEEL BUILDINGS WITH X-BRACING, USI&zwn
55
63
589
FA
M.
Hosseini
Structural Engineering Research Center Inter&
M.
Majd
Faculty of Technical and ngineering\nIslamic Az&zwn
Journal Article
2008
12
07
To compare the effect of the bracing pattern on the fragility of steel buildings with Concentrically Braced Frames (CBFs), two patterns, one with bracing in adjacent bays and the other with bracing in non-adjacent bays, were used. Fragility curves were developed by nonlinear time history analyses of buildings with 4- by 6-bay plans and 3, 5, and 7 stories, subjected to 42 different recorded accelerograms, with various peak ground acceleration and different frequency content. Two different damage indices, including story drifts, and the axial plastic deformation of bracing elements were used. Results showed that bracing in adjacent bays leads to a lower fragility of around 10% compared to bracing in non-adjacent bays. Results also show that the second index is more reliable for developing the fragility curves of steel buildings with CBFs.
To compare the effect of the bracing pattern on the fragility of steel buildings with Concentrically Braced Frames (CBFs), two patterns, one with bracing in adjacent bays and the other with bracing in non-adjacent bays, were used. Fragility curves were developed by nonlinear time history analyses of buildings with 4- by 6-bay plans and 3, 5, and 7 stories, subjected to 42 different recorded accelerograms, with various peak ground acceleration and different frequency content. Two different damage indices, including story drifts, and the axial plastic deformation of bracing elements were used. Results showed that bracing in adjacent bays leads to a lower fragility of around 10% compared to bracing in non-adjacent bays. Results also show that the second index is more reliable for developing the fragility curves of steel buildings with CBFs.
https://sjce.journals.sharif.edu/article_589_30bb3825e8f631cc6075c0f87bb4978c.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
BEHAVIOR OF EARTH DAMS WITH A CLAY CORE VERSUS MIXED CLAY MATERIALS, SUBJECTED TO DIFFERENT LOADIN
BEHAVIOR OF EARTH DAMS WITH A CLAY CORE VERSUS MIXED CLAY MATERIALS, SUBJECTED TO DIFFERENT LOADIN
65
74
590
FA
S.
Sasanian
Dept. of Civil and Environmental Engineering Ami&zw
A.
Soroush
Dept. of Civil and Environmental Engineering Ami&zw
H.S.
Jigheh
Faculty of Engineering Azarbayejan Universit&
0000-0001-6015-3437
Journal Article
2010
01
20
At the core of some earth dams, mixed clayey soil is used instead of clayey soils for some economical, technical, and workability reasons. In this paper, hypothetical earth dams, once containing clay core and then containing mixed clayey core, have been compared and analyzed numerically.The results show that during the course of dam construction with the mixed core, less excess pore water pressure is produced, as compared to the clay core. But, during a hypothetical cyclic loading on the dam crest, more pore water pressure is produced in the mixed core. Result collation also showed that the total pore water pressure induced during construction, impounding, and hypothetical cyclic loading in the clay core, is more than in the mixed core. As a result, in earth dams with a mixed core, in addition to improvement in resistance properties, less excess pore water pressure is produced compared to dams with a clay core.
At the core of some earth dams, mixed clayey soil is used instead of clayey soils for some economical, technical, and workability reasons. In this paper, hypothetical earth dams, once containing clay core and then containing mixed clayey core, have been compared and analyzed numerically.The results show that during the course of dam construction with the mixed core, less excess pore water pressure is produced, as compared to the clay core. But, during a hypothetical cyclic loading on the dam crest, more pore water pressure is produced in the mixed core. Result collation also showed that the total pore water pressure induced during construction, impounding, and hypothetical cyclic loading in the clay core, is more than in the mixed core. As a result, in earth dams with a mixed core, in addition to improvement in resistance properties, less excess pore water pressure is produced compared to dams with a clay core.
https://sjce.journals.sharif.edu/article_590_08b255a5d42b89b0585260b6f2360bdd.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
APPLICATION OF CPT DATA FOR ESTIMATING FOUNDATIONS SETTLEMENT- CASE HISTORIES
APPLICATION OF CPT DATA FOR ESTIMATING FOUNDATIONS SETTLEMENT- CASE HISTORIES
75
85
591
FA
M.
Malekdoost
Faculty of Engineering University of Guilan
A.
Eslami
Dept. of Civil and Environmental Engineering Ami&zw
Journal Article
2008
12
30
In this paper CPT data has been used for evaluation of soil stiffness (E). The CPTu records are continuous and accurate in soft soils which suffer settlement problems. In 1967, Janbu presented a relation to determine the settlement for cohesive and non-cohesive soils, regarding a stress-strain approach, based on two parameters that are called (m) and (j); modulus number and stress component, respectively. In this study, it has been attempted to correct the m and j parameters using CPT data in the form of soil behavior classification charts. A data bank has been compiled containing fifty two practical case histories, including shallow foundation full scale load tests and CPT performed close to them. The results of validation indicate that the proposed approach is able to predict the settlement close to their real values and its accuracy is more than other common methods, such as Janbu, Meyerhof and Schmertmann methods.
In this paper CPT data has been used for evaluation of soil stiffness (E). The CPTu records are continuous and accurate in soft soils which suffer settlement problems. In 1967, Janbu presented a relation to determine the settlement for cohesive and non-cohesive soils, regarding a stress-strain approach, based on two parameters that are called (m) and (j); modulus number and stress component, respectively. In this study, it has been attempted to correct the m and j parameters using CPT data in the form of soil behavior classification charts. A data bank has been compiled containing fifty two practical case histories, including shallow foundation full scale load tests and CPT performed close to them. The results of validation indicate that the proposed approach is able to predict the settlement close to their real values and its accuracy is more than other common methods, such as Janbu, Meyerhof and Schmertmann methods.
https://sjce.journals.sharif.edu/article_591_3493894fa4ea036cfc6433c3e2ee63b0.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
PERFORMANCE-BASED DESIGN OF SEISMICALLY ISOLATED STEEL STRUCTURES WITH ORDINARY OCCUPANCY I&
PERFORMANCE-BASED DESIGN OF SEISMICALLY ISOLATED STEEL STRUCTURES WITH ORDINARY OCCUPANCY I&
87
94
592
FA
M.
Tehranizadeh
Dept. of Civil and Environmental Engineering Ami&zw
P.
Boroumand
Dept. of Civil and Environmental Engineering Ami&zw
Journal Article
2009
01
03
Seismic isolation is an outstanding achievement in earthquake engineering, leading to the design of important structures and life lines, with operational to immediate occupancy levels of performance, after strong ground motions. However, taking into account technological advances in the design and manufacturing process of different kinds of isolators, base-isolation will no longer be a design strategy applicable only to very important structures; with a decline in cost, it will be used in ordinary buildings. In the latter category, there is no need to prevent the structure from nonlinear behavior under every kind of ground motion, and the designer can take advantage of both isolation technology, in order to reduce the seismic demand, and a performance-based design approach, using the inelastic capacity of the structural members, which will lead to a more economical structure with lighter frames. In this research, taking into account the nonlinear behavior of two 5 and 8 story base-isolated buildings with special moment steel frames and designed in accordance with ASCE 7-05 and AISC 360-05 seismic and structural regulations for base-isolated structures under near-field earthquakes compatible with BSE-1 and BSE-2 seismic hazard levels, the performance levels of the structures under very strong near-field motion (BSE-2) are changed from immediate occupancy to life safety, with respect to the acceptance criteria of FEMA 356 guidelines.
Seismic isolation is an outstanding achievement in earthquake engineering, leading to the design of important structures and life lines, with operational to immediate occupancy levels of performance, after strong ground motions. However, taking into account technological advances in the design and manufacturing process of different kinds of isolators, base-isolation will no longer be a design strategy applicable only to very important structures; with a decline in cost, it will be used in ordinary buildings. In the latter category, there is no need to prevent the structure from nonlinear behavior under every kind of ground motion, and the designer can take advantage of both isolation technology, in order to reduce the seismic demand, and a performance-based design approach, using the inelastic capacity of the structural members, which will lead to a more economical structure with lighter frames. In this research, taking into account the nonlinear behavior of two 5 and 8 story base-isolated buildings with special moment steel frames and designed in accordance with ASCE 7-05 and AISC 360-05 seismic and structural regulations for base-isolated structures under near-field earthquakes compatible with BSE-1 and BSE-2 seismic hazard levels, the performance levels of the structures under very strong near-field motion (BSE-2) are changed from immediate occupancy to life safety, with respect to the acceptance criteria of FEMA 356 guidelines.
https://sjce.journals.sharif.edu/article_592_dbe272bab69f8e13f14b405e038deb64.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
DEVELOPMENT AND APPLICATION OF A LONG-TERM WATER ALLOCATION MODEL IN ASSESSMENT OF WATER POLICIE&
DEVELOPMENT AND APPLICATION OF A LONG-TERM WATER ALLOCATION MODEL IN ASSESSMENT OF WATER POLICIE&
95
105
593
FA
R.
Ardakanian
Dept. of Civil Engineering Sharif University of Te&
A.
Karimi
Dept. of Civil Engineering Sharif University of Te&
Journal Article
2009
01
12
Water sector policy makers are interested in assessing the long-term impacts of adopted policies on water allocation for stakeholder benefits. To assess the impacts of policies on stakeholders, a model that considers water supply-demand interaction is necessary. Research in this field mostly deals with the short term modeling of water supply-demand interaction. In this research, a dynamic water allocation model is developed, which considers long-term water supply-demand interaction through the inclusion of socio-economic parameters representing water allocation problems and stakeholder benefits.In this research, the net income of takeholders, employment of a labor force and the allocated water to minimum river flow requirements, are socio-economic and environmental parameters included in the objective function to be maximized. Agricultural and industrial water demands are considered to interact with the water supply and with each other. Stakeholders are comprised of agricultural, industrial, water allocation and environmental sectors. This model is used for assessment of the long-term impacts of two policies; the first considers 5% improvement in efficiencies and the second considers the present state continuing without improvement in efficiency. Policies are applied to and assessed for an example water basin comprised of multi-reservoirs and different water demands for a 30 year planning horizon. Criteria are defined for summarizing the long-term impact of policies in the water basin. Based on these criteria values, the second policy is favored in comparison with the first.
Water sector policy makers are interested in assessing the long-term impacts of adopted policies on water allocation for stakeholder benefits. To assess the impacts of policies on stakeholders, a model that considers water supply-demand interaction is necessary. Research in this field mostly deals with the short term modeling of water supply-demand interaction. In this research, a dynamic water allocation model is developed, which considers long-term water supply-demand interaction through the inclusion of socio-economic parameters representing water allocation problems and stakeholder benefits.In this research, the net income of takeholders, employment of a labor force and the allocated water to minimum river flow requirements, are socio-economic and environmental parameters included in the objective function to be maximized. Agricultural and industrial water demands are considered to interact with the water supply and with each other. Stakeholders are comprised of agricultural, industrial, water allocation and environmental sectors. This model is used for assessment of the long-term impacts of two policies; the first considers 5% improvement in efficiencies and the second considers the present state continuing without improvement in efficiency. Policies are applied to and assessed for an example water basin comprised of multi-reservoirs and different water demands for a 30 year planning horizon. Criteria are defined for summarizing the long-term impact of policies in the water basin. Based on these criteria values, the second policy is favored in comparison with the first.
https://sjce.journals.sharif.edu/article_593_acc3e0404646c57502b480dc052c4fe1.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
EFFECTIVE PARAMETERS ON DESIGN SPECTRA IN NEAR-FAULT AND PROPOSED SPECTRUM USING FORWARD DIREC&zw
EFFECTIVE PARAMETERS ON DESIGN SPECTRA IN NEAR-FAULT AND PROPOSED SPECTRUM USING FORWARD DIREC&zw
107
113
594
FA
M.
Tehranizadeh
Dept. of Civil and Environmental Engineering Ami&am
H.
Taheri
Dept. of Civil and Environmental Engineering Ami&zw
Journal Article
2009
01
28
Strong ground motion during an earthquake is one of the most important effects that engineers have to face. Hence, achieving a prospected performance during and after an event is necessary. Since present seismic design codes are not proper enough in near-fault conditions, an appropriate design procedure (like proper design spectra) is strongly needed. In near-fault, not only forward directivity is important, but, also, because of less attenuation, strong ground motion has much more energy.
Strong ground motion during an earthquake is one of the most important effects that engineers have to face. Hence, achieving a prospected performance during and after an event is necessary. Since present seismic design codes are not proper enough in near-fault conditions, an appropriate design procedure (like proper design spectra) is strongly needed. In near-fault, not only forward directivity is important, but, also, because of less attenuation, strong ground motion has much more energy.
https://sjce.journals.sharif.edu/article_594_076a0c97d09cf1a0ec3e19c7f2529f2b.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
EVALUATION OF MODAL PUSHOVER ANALYSIS PROCEDURE USING MOMENT RESIST FRAMES WITH SEMI-RIGID CON&zwn
EVALUATION OF MODAL PUSHOVER ANALYSIS PROCEDURE USING MOMENT RESIST FRAMES WITH SEMI-RIGID CON&zwn
115
122
595
FA
P.
Zarfam
Dept. of Civil Engineering Sharif University of Te&
R.
Saidinia
Dept. of Civil Engineering Sharif University of Te&
M.
Mofid
Dept. of Civil Engineering Sharif University of Te&
Journal Article
2008
11
23
The recently developed nonlinear static analysis procedures have been shown to be a significant improvement over analysis procedures currently used in structural engineering practices. Nonlinear static analysis procedures in estimating the seismic demands of structures are much simpler and faster than nonlinear dynamic analysis procedures. Among these procedures, modal pushover analysis (MPA) will present a very good approximation of nonlinear response history analysis (NLRHA). There are two kinds of connection, pinned and rigid, which have some flexibility. Therefore, these connections, with different rigidity, can be considered as semi-rigid onnections. Since the accuracy of MPA procedures has not been verified for steel moment resist frames with semi-rigid connections, in this study, we investigate this subject. For this purpose, MPA (approximate) and NLRHA (exact) are used for frames with different rigidity percentiles of connections. It seems that the procedure accuracy tends to decrease by increasing the number of stories and decreasing the rigidity percentiles of semi-rigid connections. Finally, the MPA procedure is simplified to facilitate its implementation in engineering practices and the accuracy of this simplified procedure is documented, especially for bottom and mid stories.
The recently developed nonlinear static analysis procedures have been shown to be a significant improvement over analysis procedures currently used in structural engineering practices. Nonlinear static analysis procedures in estimating the seismic demands of structures are much simpler and faster than nonlinear dynamic analysis procedures. Among these procedures, modal pushover analysis (MPA) will present a very good approximation of nonlinear response history analysis (NLRHA). There are two kinds of connection, pinned and rigid, which have some flexibility. Therefore, these connections, with different rigidity, can be considered as semi-rigid onnections. Since the accuracy of MPA procedures has not been verified for steel moment resist frames with semi-rigid connections, in this study, we investigate this subject. For this purpose, MPA (approximate) and NLRHA (exact) are used for frames with different rigidity percentiles of connections. It seems that the procedure accuracy tends to decrease by increasing the number of stories and decreasing the rigidity percentiles of semi-rigid connections. Finally, the MPA procedure is simplified to facilitate its implementation in engineering practices and the accuracy of this simplified procedure is documented, especially for bottom and mid stories.
https://sjce.journals.sharif.edu/article_595_04ecb1fa28506ccb6f72b12c0245ddbc.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
SEISMIC DESIGN OF ECCENTRICALLY BRACED FRAMES WITH MIDDLE LINK BEAM USING ENERGY BASED METHOD
SEISMIC DESIGN OF ECCENTRICALLY BRACED FRAMES WITH MIDDLE LINK BEAM USING ENERGY BASED METHOD
123
131
596
FA
S. R.
Mirghaderi
Center of Excellence for Engineering and Manage&zwn
S.
Dastmalchi
Center of Excellence for Engineering and Manage&zwn
S.M.
Zahrai
Center of Excellence for Engineering and Manage&zwn
Journal Article
2008
12
09
The use of energy, as means to derive seismic design forces, to design eccentrically braced frames with a moment link, is presented in this paper. The ultimate design forces are derived from input energy for a selected design pseudovelocity spectrum, a selected plastic yield mechanism, a selected target deformation level, and a selected plastic angle of link beam. This method eliminates the need for a drift check after the structure is designed for strength. This method can lead to a desirable yield mechanism for structures in an ultimate state. For comparison between the seismic response of structures designed with an equivalent static method and an energy-based method, a 10 story frame is designed considering the above two methods, from which, the results from nonlinear analyses of the frames, are compared. The results indicate that a design by an energy-based method can lead to more dissipation of input energy and more ductility of structures.
The use of energy, as means to derive seismic design forces, to design eccentrically braced frames with a moment link, is presented in this paper. The ultimate design forces are derived from input energy for a selected design pseudovelocity spectrum, a selected plastic yield mechanism, a selected target deformation level, and a selected plastic angle of link beam. This method eliminates the need for a drift check after the structure is designed for strength. This method can lead to a desirable yield mechanism for structures in an ultimate state. For comparison between the seismic response of structures designed with an equivalent static method and an energy-based method, a 10 story frame is designed considering the above two methods, from which, the results from nonlinear analyses of the frames, are compared. The results indicate that a design by an energy-based method can lead to more dissipation of input energy and more ductility of structures.
https://sjce.journals.sharif.edu/article_596_b2eeb7362ef83deff5c7813a67e14f0a.pdf
Sharif University of Technology
Sharif Journal of Civil Engineering
2676-4768
Volume 2-27
1
2011
03
21
THE OPTIMUM METHODS OF STEEL PLATE SHEAR WALL MODELINGS
THE OPTIMUM METHODS OF STEEL PLATE SHEAR WALL MODELINGS
133
138
597
FA
G.
Ghodrati Amiri
School of Civil Engineering\nIran University Sci&zwn
0000-0003-3244-0943
B.
Mirmiran
School of Civil Engineering\nIran University Sci&zwn
Journal Article
2008
12
30
Nowadays, the increasing demands of seismic retrofitting result in further usage of SPSW.SPSW has been used since 1970 and has many advantages, such as ductility, strength, good energy dissipation, good performance and economic desirability, and easy instalation. In this study, first, the varieties of SPSW modelings are evaluated, based on specific testing with adequate data. Second, the optimum method of modeling is supposed from those results. At the end; the optimum method is applied to a frame with 4, 8 and 12 levels.
Nowadays, the increasing demands of seismic retrofitting result in further usage of SPSW.SPSW has been used since 1970 and has many advantages, such as ductility, strength, good energy dissipation, good performance and economic desirability, and easy instalation. In this study, first, the varieties of SPSW modelings are evaluated, based on specific testing with adequate data. Second, the optimum method of modeling is supposed from those results. At the end; the optimum method is applied to a frame with 4, 8 and 12 levels.
https://sjce.journals.sharif.edu/article_597_08c5433a60135c32e34f46a71175850c.pdf