filter by: Publication Year
(Descending) Articles
Soil Dynamics and Earthquake Engineering (02677261) 199
This study presents a comprehensive, time-resolved investigation into the effects of localised damage and subsequent restoration on the dynamic behaviour of a semi-circular brick-and-gypsum masonry arch, representative of Persian architectural heritage. Using Operational Modal Analysis (OMA) with Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI), dynamic responses were evaluated across intact, under three distinct damage scenarios, and following restoration. The findings reveal that both damage location and symmetry significantly influence the arch's dynamic properties. Localised damage led to substantial reductions in natural frequencies, with mode two exhibiting up to 26.6 % reduction in initial damage and 43.5 % in the most severe scenario. Symmetric damage reduced sensitivity in fundamental modes, underscoring the need for multi-modal assessment. Average modal damping ratios increased by up to 107.2 providing more consistent and reliable detection compared to EFDD. Restoration using traditional gypsum mortar significantly improved dynamic characteristics, with natural frequencies recovering by approximately 13.5 % EFDD and 13 % SSI relative to the damaged state. Modal parameters stabilised within 24 h post-restoration; however, certain modes showed incomplete recovery, especially near sensor locations indicating residual stiffness deficits. Damage detection indices of Modal Assurance Criterion (MAC), Normalised Modal Difference (NMD), and Coordinate Modal Assurance Criterion (COMAC) have effectively identified damage, reinforcing their critical role in heritage structural health monitoring. The research highlights the importance of considering restoration as a time-dependent, evolving process, and advocates for integrated and multi-parameter monitoring frameworks. The results offer practical insights for optimising the conservation strategies of historic masonry structures, with recommendations for future work addressing environmental effects, numerical modelling, and advanced restoration materials. © 2025 Elsevier Ltd
International Journal for Numerical Methods in Engineering (00295981) 126(14)
In this study, the bending, buckling, and free vibration analysis of bi-directional functionally graded porous microbeams with variable thickness are investigated. By utilizing the modified strain gradient theory (MSGT) in conjunction with a sinusoidal shear deformation theory, governing equations are derived using Hamilton's principle within the framework of the non-uniform rational B-spline (NURBS)-based isogeometric analysis (IGA). In addition, the C2-continuity requirement can be easily achieved by increasing the order of the NURBS basis functions. The MLSPs and the material properties of microbeams vary along with both thickness and axial directions based on the rule of mixture scheme. To consider the effects of porosity, two even and uneven distributions are considered. After verifying the accuracy of the presented approach, the influence of the aspect ratio, gradient indices, different boundary conditions, porosity parameters, variable MLSPs, and thickness on the bending, buckling, and free vibration characteristics of microbeams are investigated. © 2025 John Wiley & Sons Ltd.
Thin-Walled Structures (02638231) 211
In this paper, the isogeometric analysis (IGA) is extended to study the size-dependent behavior of bending, buckling and free vibration of in-plane bi-directional functionally graded porous microplates with variable thickness. In order to capture the effect of size, the modified strain gradient elasticity theory, which has three length scale parameters, is used. Regarding to the third-order shear deformation theory, the equations of motions are derived by using the Hamilton's principle and then are discretized based on the IGA approach. The material properties vary continuously through in-plane directions by employing the rule of mixture and the porosity distribution is considered an even type. The C2-continuity requirement can be easily achieved by increasing the order of the non-uniform rational B-spline (NURBS) basis functions larger than two. The influences of the size effect, aspect ratios, boundary conditions, thickness variations, material gradations, and porosity distributions on the deflections, the fundamental natural frequencies, and the buckling load values of the rectangular, circular and elliptical microplates are studied. The obtained results are compared with the previously published studies to show the performance and efficiency of the present research. © 2025 Elsevier Ltd
Structural Engineering and Mechanics (12254568) 89(2)pp. 181-197
A numerical method is presented in this paper, for buckling analysis of thin arbitrary stiffened composite cylindrical shells under axial compression. The stiffeners can be placed inside and outside of the shell. The shell and stiffeners are operated as discrete elements, and their interactions are taking place through the compatibility conditions along their intersecting lines. The governing equations of motion are obtained based on Koiter's theory and solved by utilizing the principle of the minimum potential energy. Then, the buckling load coefficient and the critical buckling load are computed by solving characteristic equations. In this formulation, the elastic and geometric stiffness matrices of a single curved strip of the shell and stiffeners can be located anywhere within the shell element and in any direction are provided. Moreover, five stiffened composite shell specimens are made and tested under axial compression loading. The reliability of the presented method is validated by comparing its numerical results with those of commercial software, experiments, and other published numerical results. In addition, by using the ANSYS code, a 3-D finite element model that takes the exact geometric arrangement and the properties of the stiffeners and the shell into consideration is built. Finally, the effects of Poisson's ratio, shell length-to-radius ratio, shell thickness, cross-sectional area, angle, eccentricity, torsional stiffness, numbers and geometric configuration of stiffeners on the buckling of stiffened composite shells with various end conditions are computed. The results gained can be used as a meaningful benchmark for researchers to validate their analytical and numerical methods. Copyright © 2024 Techno-Press, Ltd.
This study includes extensive compression tests on clay brick units, gypsum mortar, and masonry configurations, incorporating both gypsum and cement mortar, across four distinct scales 1:1, 1:2, 1:4, and 1:6. It investigates the relationship between compressive strength and modulus of elasticity, with the aim of providing precise estimation tools for these important mechanical properties. Systematic experimentation is employed, and scatter diagrams illustrate the dynamic interplay between modulus of elasticity and compressive strength. The derived coefficients, validated against experimental data, verify the accuracy of the proposed relationships. Specifically, the derived coefficient η, representing the ratio of modulus of elasticity to compressive strength, exhibits scale-dependent variations. For brick units, η ranges from 104 for the 1:1 scale to 126 for the 1:6 scale, emphasising the impact of size. Additionally, the coefficient η for gypsum mortar demonstrates a 20% increase with a rise in the water-to-gypsum ratio. Regarding masonry configurations, the coefficient η in the BS method varies from 91 for the 1:6 scale to 139 for the 1:2 scale. In the RILEM method, the coefficient η ranges from 48 for the 1:6 scale to 105 for the 1:1 scale. The proposed relationships display a negligible deviation from experimental results, affirming their robustness. Furthermore, a relationship is introduced for estimating masonry compressive strength based on the compressive strength of both the brick and the mortar at different scales. The accuracy of this relationship is verified by its minor deviation from experimental results. © 2024 Institution of Structural Engineers
European Journal of Environmental and Civil Engineering (21167214) 28(9)pp. 1968-2001
This paper addresses the imperative need for understanding the mechanical properties of clay brick masonry with gypsum mortar, the primary construction material in Persian historical buildings, to facilitate accurate restoration efforts. Given the constraints of heritage preservation, destructive tests on large-scale specimens are unfeasible. As a viable alternative, this research employs scaled-down specimens to investigate the flexural strength. For the first time, Persian clay brick masonry with gypsum mortar assemblages have been tested at three scales of 1:2, 1:4 and 1:6 to determine the flexural strength. The paper introduces new relationships between the flexural strength of brick masonry and brick size. Furthermore, it establishes a correlation between the flexural strength of the brick masonry specimens and the flexural strengths of both the brick and the gypsum mortar. Additionally, some specimens incorporate cement mortar instead of gypsum mortar for result comparison. The obtained results reveal the profound influence of mortar type and thickness, along with brick dimensions, on flexural strength. The flexural strength of brick masonry increases with decreasing brick size. By reducing the size of bricks, the ratio of compressive strength to flexural strength decreases, offering key insights for restoration efforts. © 2023 Informa UK Limited, trading as Taylor & Francis Group.
Mechanics of Advanced Materials and Structures (15210596) 31(9)pp. 2008-2028
The buckling behavior of moderately thick and thick stiffened composite plates with different stiffener layouts is formulated based on the higher-order shear deformation theory. This investigation is performed under axial compression using the Finite Strip Method and experiment. The effects of dimensions, orientation, eccentricity, torsional stiffness, position and geometric configuration of stiffeners on the buckling load coefficient are achieved by employing the principle of minimum potential energy. Six grid-stiffened composite plate specimens with ortho-grid, angle-grid, and orthotropic-grid stiffeners are tested. The results of the presented method show good outcomes with those of experimental tests and the finite element ANSYS code. © 2022 Taylor & Francis Group, LLC.
A new type of steel reduced beam section connection using longitudinal slots in the beam flanges is introduced. The effect of different parameters has been studied by the non-linear three-dimensional finite element method. Parameters have been the distance between the slot and column face, the length and width of the slot, the distance between the slot and the edge of the beam flange, the number of slots, the distance between slots, and the dimensions of the beam. The displacement controlled cyclic loading protocol recommended by SAC has been imposed. The von Mises yield criterion has been used. Obtained results show that creating the slots in the beam flange improves considerably the performance of the connection. The bending moment at the column face and plastic strains in the weld decrease by 32% and 94%, respectively, by increasing the slot length by 264%. The bending moment and dissipated energy reduce by 59% and 66%, respectively, when the slot width is increased by 430%. By increasing the length and width of the slot from a specific value and by moving the slot towards the beam web, the behaviour of the connection becomes unsatisfactory. The effect of the beam height is more than that of other dimensions of the beam. Based on the results obtained, recommendations for the design implications related to the geometric dimensions of the slots have been formulated. © 2023 Institution of Structural Engineers
Alaei, Alireza ,
Hejazi, Mehrdad ,
Alaei, A. ,
Mehrdad mohammad hejazi, S.A. ,
Vintzileou, E. ,
Miltiadou-fezans, A. ,
Skłodowski, M. Structures (23520124) 50pp. 148-160
This paper presents the effects of changes in temperature and moisture content on the dynamic properties of semi-circular arches made of clay brick and gypsum mortar constructed and tested in the laboratory. First, the mechanical properties of the materials used were determined by experimental tests. Operational Modal Analysis was then performed for each condition to measure natural frequencies, mode shapes, and modal damping ratios. An empirical equation for estimating the natural frequencies of the studied arch at different material moisture contents was proposed using the obtained results from experimental tests. Finally, the Finite Element Model Updating Method (FEMU) was applied to calibrate some of the material mechanical properties in modelled arches. In contrast to the effect of moisture, temperature changes showed a difficulty to interpret effect on the dynamic properties of the arch. On the other hand, Poisson's ratio did not affect the dynamic behaviour of the specimen.
European Physical Journal Plus (21905444) 138(3)
In this paper, the dynamic properties of three types of Persian brick masonry arches, semi-circular, ordinary pointed and ordinary four-centred have been studied. These arches were constructed with clay brick, and gypsum mortar in the laboratory and experimental tests were conducted. First, the mechanical properties of the used materials were determined. Then, operational modal analysis was used to measure the dynamic properties of the constructed arches. Afterwards, a horizontal displacement was applied to the arch support to create a crack. The arches were repaired then, and dynamic identification was performed for each case. Several damage detection methods were used to evaluate their ability to detect damage in brick masonry arches. Finite element model updating was used to track changes in the material properties of arches and to match numerical results with dynamic laboratory results. The study showed that damage has a significant effect on the dynamic properties of arches. Repairing the damage partially restores the dynamic parameters to the undamaged condition, but it cannot completely transform the arch into an arch without damage. Damage detection methods were able to identify the occurrence of damage to the arches, but there are limitations in the use of these methods. Diagrams were generated to estimate the static moduli of brick and of gypsum mortar from the dynamic modulus of elasticity of the assemblage of brick and gypsum mortar. © 2023, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.
Mechanics Based Design of Structures and Machines (15397742) 51(4)pp. 2251-2278
The Finite Strip Method (FSM) was employed to study the buckling behavior of laminated glass fiber-reinforced polymer (GFRP) stiffened plates with different boundary conditions under axial compression. The theoretical formulation was established based on the first-order shear deformation theory (FSDT) for the thin plate and the stiffener. In this formulation, the stiffeners are not required to be placed on the nodal lines. This feature is considered useful in modeling the stiffened plates in which the stiffener elements are placed arbitrarily in complex planforms. Experimental, numerical and analytical studies were conducted to investigate the effects of the plate width-to-thickness ratio, the stiffener thickness-to-width ratio, dimensions, angle, eccentricity, torsional stiffness and geometric configuration of stiffeners on axial buckling capacity. Furthermore, the obtained results of the analytical method were compared with experimental results and ANSYS code to show its accuracy and convergence. The advantages of the present are that number of elements is much less and the mesh refinement process is much more convenient than commercial finite element software and traditional finite element method (FEM). Therefore, time consumed for analysis is less than the codes which work based on the finite element method. © 2021 Taylor & Francis Group, LLC.
Structures (23520124) 47pp. 665-680
In this paper, the performance of Persian skewed brick masonry arch bridges under uniform and line loads has been investigated. Three types of semi-circular, pointed and four-centred arches have been studied. Bridges with two spans and six spans have been analysed using the three-dimensional non-linear finite element method. The parameters considered are four skew angles, three pier width to span ratios, three bridge width to span ratios, three pier height to span ratios, and three deck thickness to span ratios. Loading includes uniformly distributed load on the entire surface of the bridge deck, line load at the middle of the middle pier, and line load at the apex of one of the arches. The suitable ranges of the skew angle to create the maximum load-bearing capacity have been obtained for different loadings, different types of the arches and other parameters. © 2022 Institution of Structural Engineers
European Physical Journal Plus (21905444) 138(1)
In this paper, the effect of imperfection on the load bearing capacity of Persian brick masonry arches has been studied. Loadings applied are support settlement, support rotation, temperature and the earthquake. Seven shapes have been considered for arches including semi-circular, pointed, and four-centred shapes, the last two shapes have three categories of drop, ordinary, and raised shapes each. Support settlement and support rotation are applied to all seven shapes. Temperature and earthquake are applied to three shapes including semi-circular, ordinary four-centred, and ordinary pointed arches. Imperfection is considered in two different locations relative to the support. Additionally, the imperfection is placed once at the extrados and once at the intrados. Nonlinear finite element analysis is performed by using the ANSYS code. The Willam-Warnke failure criterion is used for the brick masonry. The types of arches showing better performance have been determined for various imperfection cases and different loadings. © 2023, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.
Acta Mechanica (16196937) 234(10)pp. 4535-4557
This paper presents a size-dependent study on the free vibration behaviour of the functionally graded (FG) porous curved microbeams. Based on the different higher-order shear deformation models and the modified strain gradient theory, the governing equations are derived using Hamilton’s principle. Then, the isogeometric analysis approach is employed to solve these equations. Besides, the material properties and the material length scale parameters (MLSPs) vary along the thickness direction of the FG curved microbeams according to the rule of mixture scheme. Also, two types of porosity distributions across the thickness, including even and uneven, are considered. By increasing the order of the non-uniform rational b-spline (MLSPs) basis functions, the C2-continuity requirement can be easily achieved. To establish the validity of the proposed method, the present results are compared with those from the previous studies. Finally, the effects of the variable MLSPs, porosity parameter, material gradient indices, curvature and different boundary conditions on free vibration response of circular, elliptical and parabolic FG porous microbeams are investigated. The obtained results reveal that the size-dependent effects increase the natural frequency as well as porosity decreases it because of decreasing the stiffness. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.
Engineering Failure Analysis (13506307) 152
In this paper, the effect of different parameters on the structural behaviour of scaled brick masonry arches is studied by conducting experimental tests and numerical analysis using the non-linear three-dimensional finite element. Arches at a scale 1:20 made of clay brick and gypsum mortar are constructed in the laboratory. Seven shapes of Persian arches are selected for the arches. Arches are under concentrated load once applied at the mid-span and once applied at the quarter-span. Some arches are subjected to the vertical displacement of the support. Other parameters studied are the angle of the embrace and the variation of the thickness. Results indicate that imposing a concentrated load at the mid-span is more critical than at the quarter-span. Arches with higher rises show higher capacities. The pointed arch is the most sensitive arch to the support vertical displacement. Smaller angles of embrace result in reducing the load-bearing capacity and the rate of reducing the capacity is similar for different arch shapes. The semi-circular arch has the greatest resistance to the vertical displacement of the support. The load location, quarter-span, and supports are prone to cracking and crushing. © 2023 Elsevier Ltd
Ingegneria Sismica (03931420) 40(2)pp. 1-24
The effect of the dimensions and locations of the openings and the influence of inclination on dynamic response of nine Persian historical brick masonry minarets constructed in the eleventh to fourteenth centuries is studied. The operational modal test was performed on a minaret constructed in the laboratory and the frequencies were obtained by the ARTeMIS software, and the ANSYS software was used for updating its finite element model. A range was determined for the values of the modulus of elasticity and bulk density to obtain acceptable ranges for the frequencies of the minarets. Then finite element model updating of the historical minarets was performed to determine their frequencies. Several dimensions and locations were assumed for the openings and two inclination angles were considered to study their effect on the frequencies. Minarets were then subjected to earthquakes in order to investigate the effect of openings and inclination on their seismic response. © 2023 Patron Editore S.r.l.. All Rights Reserved.
Construction and Building Materials (09500618) 372
In this paper, the structural behaviour of Persian brick masonry groined quadripartite, sexpartite and octopartite vaults is studied. Three different spans, three different pier heights and three different pier widths adopted from real structures are considered. Seven different cross-sectional shapes are selected for the vaults and the supporting arches. Vaults are subjected to four cases of pier settlement and seven cases of pier rotation. Three-dimensional non-linear finite element has been used for analysis. Results show that the load bearing capacity is sensitive to the type of the vault and the shape of the arches, to the type of pier settlement and pier rotation. Ranges for the pier height to the pier width ratio for the highest resistance of the vaults are proposed for pier settlement and rotation. © 2023 Elsevier Ltd
In this paper, several parametric studies were performed on the dynamic behaviour of seven types of Persian brick masonry arches using the finite element method. The studied parameters included the arch types, arch thickness, arch scale, support conditions, and brick arrangement. The finite element models were calibrated using experimental results obtained from operational modal analysis of an arch constructed in the laboratory. The parametric studies have shown that the type of arch significantly affects the natural frequencies. The increasing of arch thickness leads to increase of the natural frequencies. Simply supported arches exhibit reduced natural frequencies, compared to those fixed at their supports. Brick arrangement has little effect on the natural frequency. Finally, an empirical equation for estimating the fundamental frequency of the studied arches was proposed using the obtained results from finite element models. The high accuracy of the empirical equation was tested through measurements on a real full-scale arch. © 2023 Institution of Structural Engineers
Engineering Failure Analysis (13506307) 142
In this paper, the structural behaviour of the Obelisk of Theodosius and Walled Obelisk, located near the Sultan Ahmed Mosque in Istanbul, is investigated. The Obelisk of Theodosius is made of an integrated and solid red granite that stands on four pieces of bronze cubes and large pieces of stone cubes. The Walled Obelisk is made of small pieces of limestone that stand on only one large piece of stone cube, without bronze cubes. The purpose of this study is the comparison of the structural behaviour of these two obelisks and the effect of their supporting base on their performance under seismic loading. The nonlinear three-dimensional finite element method is used for modelling and the Willam-Warnke failure criterion is adopted for investigation of brittle fracture mechanism. The results of analysis show that the Walled Obelisk is more flexible than the Obelisk of Theodosius. However, the existence of four bronze cubes and four red granite cubes at the corners of the supporting base increases the flexibility of the Obelisk of Theodosius. © 2022 Elsevier Ltd
Journal of Building Engineering (23527102) 54
In this paper, the in–plane cyclic behaviour of half-timbered walls with fired brick infill, widely used in traditional half-timbered buildings is studied. Structural analysis is performed by the finite element ANSYS code assuming non-linear behaviour of materials. Micro-modelling approach is used with different properties for the timber and the masonry. Fifty-seven different models are analysed and compared in terms of load-bearing capacity and energy dissipation. The results of analysis show that vertical and horizontal wooden members of the wooden framework have little effect on changing the load-bearing capacity and energy dissipation. Diagonal wooden members sharply increase the load-bearing capacity and energy dissipation. Openings reduce the load-bearing capacity and energy dissipation. Because the diagonal wooden members significantly increase the load-bearing capacity of the wooden frame at the appropriate arrangement of diagonal wooden members, it is possible to reduce the duty of the masonry infill in lateral load-bearing. © 2022 Elsevier Ltd
European Physical Journal Plus (21905444) 137(6)
In this paper, the isogeometric analysis based on the non-uniform rational B-spline (NURBS) basis functions is used to study of the bending, buckling and free vibration of the multi-directional functionally graded porous plates with variable thickness. The third-order shear deformation theory is used to account for shear deformation effect, which does not require any shear correction factors. The material properties of the plates are estimated by the rule of mixture and the Mori–Tanaka scheme. The C1 required degree of continuity is easily obtained by increasing the order of the NURBS basis functions. The governing equations of motion are extracted by Hamilton’s principle and then discretised by the isogeometric analysis approach. The effect of different length-to-thickness ratios, material gradations, thickness variations, porosity parameters, and the different boundary conditions on the bending, buckling and free vibration of rectangular, circular and elliptical multi-directional functionally graded porous plates are evaluated. The effectiveness of the proposed method is verified by comparing its numerical results with those of other methods reported in the relevant literature. The presented results show that the variable thickness, porosity parameter and material gradations have a significant effect on the mechanical responses of the plates. Decreasing the thickness and increasing the porosity due to reducing the stiffness of the plate decrease the buckling load and frequencies and increase the deformation of the plate. © 2022, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.
Structures (23520124) 33pp. 4514-4537
This research presents a study on the buckling behaviour of the stiffened cylindrical shells made of laminated glass fibre-reinforced polymer (GFRP) with arbitrary stiffeners under axial compression by using the curved finite strip method. The stiffeners can be positioned at the inner and outer surfaces of the shell, and is no need to be located on the nodal lines. The governing equations of motion are extracted from Koiter's theory based on the first-order shear deformation theory and solved employing the principle of the minimum potential energy. Then, both the critical buckling load and the buckling load coefficient are calculated by solving characteristic equations. Boundary conditions considered are simple-simple, clamped–clamped, and clamped-simple supports. A relatively high-order polynomial function for the displacement components in the transverse direction is assumed for the shell and the stiffeners. A displacement model is assumed with twenty-four degrees of freedom arranged at four nodal lines for each strip. To validating the proposed method, the results of this investigation are compared with the finite element, experimental and other published numerical results. The benefits of this method are that number of elements, and therefore time consumed for analysis is much less, and the mesh refinement process is much more convenient than the conventional finite element method. Finally, the effects of the different parameters such as Poisson's ratio, boundary condition, thickness variations and geometrical parameters of shell and stiffeners, angle, eccentricity, torsional stiffness, cross-sectional area, number of stiffeners on the buckling are studied. The results obtained can be employed as a significant benchmark for researchers to verify their analytical and numerical approaches. © 2021 Institution of Structural Engineers
Measurement: Journal of the International Measurement Confederation (02632241) 172
A large number of historical buildings of Iran are made of brick masonry with gypsum mortar. For structural assessment of the buildings, information about the mechanical properties of the materials is required in order to analyse the structures and in some cases to propose restoration or strengthening for them. Taking masonry specimens with actual scale from historical buildings is not allowed and also testing on actual scale specimens in the laboratory is costly. Therefore, if the mechanical properties of the materials are obtained from a scaled model, the small scale specimens can be used for full scale structures. This paper investigates the effect of scale on the compressive strength and modulus of elasticity of brick masonry with gypsum mortar. The tests were conducted on two types of specimens at 1:1, 1:2, 1:4, and 1:6 scales based on two different standards. Scaled bricks were cut from full scale bricks. At some scales, cement mortar was used instead of gypsum mortar to compare the results. Obtained results show that the compressive strength and modulus of elasticity decrease by reducing the sizes. Furthermore, the material type, volume, and thickness of the mortar used in the wall considerably affect the compressive strength. Also, using the relationships obtained in this study, it is possible to predict the compressive strength and modulus of elasticity of the samples at any scale. © 2020 Elsevier Ltd
Structures (23520124) 34pp. 1710-1719
In this paper, the best geometrical shapes of Persian brick masonry single-shell domes under uniform pressure have been obtained and then the failure concentrated load has been determined. Seven different cross-sectional shapes with three different spans were considered. Three-dimensional finite element analysis was performed with the assumption of non-linear behaviour for materials. The minimum ratio of the apex thickness to base thickness (k) for which the failure load to dome weight ratio was a maximum was taken as the index for the best shape. For uniform pressure, k = 0.2, k = 0.08 to 0.3, and k = 0.144 to 0.54 were the best ratios for semi-circular, pointed and four-centred domes, respectively. The failure load of domes with best shapes under concentrated loads was more than that of other shapes. © 2021 Institution of Structural Engineers
Journal of Building Engineering (23527102) 33
In this paper, three new stress-strain relationships for brick masonry with gypsum mortar and cement mortar are presented. The relationships are developed based on experimental data taken from specimens at 1:4 and 1:6 scales constructed according to two different standards. It is shown that suggested strain-strain relationships are highly consistent with the experimental results for brick masonry wallettes with gypsum mortar and with cement mortar at different scales, including at full scale. It is presented that the accuracy of the developed relationships is more than stress-strain relationships suggested by other researchers. © 2020 Elsevier Ltd
International Journal of Steel Structures (20936311) 20(5)pp. 1765-1782
In eccentrically braced frames (EBFs), the link beam is the main factor determining the behavior of this type of system. In order to enhance the ductility and delaying the web and flange buckling, the link beam is reinforced using intermediate web stiffeners to improve its performance and energy dissipation capacity. The web stiffeners spacing criteria is based on short links under pure shear, which have been applied without considering the bending effect on intermediate links. In this paper, first the effects of stiffener details and section geometry on the link behavior are investigated using finite element modeling, and then by proposing an optimization model, new spacing is proposed for stiffeners of intermediate links that is also consistent with bending distribution, and enhances the performance of intermediate links significantly. To further investigate the results of the optimization model and sensitivity analyses results, the behavior of a total of 52 short, intermediate and long links with different lengths and sections is simulated and investigated under cyclic loading based on ANSI/AISC 341-10 (Seismic provisions for structural steel buildings, Chicago, American Institute of Steel Construction, 2010) using ABAQUS. The results show that the section geometry in W-beams affects the stiffeners spacing and thereby, the behavior of intermediate and long links. According to the obtained results in short links, stiffeners spacing are very conservative and can be increased, and for intermediate links, adjusting the stiffeners spacing based on the proposed optimization model can significantly enhance the performance of the link beam. © 2020, Korean Society of Steel Construction.
Engineering Failure Analysis (13506307) 118
In this paper, the structural analysis of Persian brick masonry barrel vaults with hollow spandrels (konu) with seven different arches of semi-circular, drop, ordinary and raised pointed, and drop, ordinary and raised four-centred under uniformly distributed load, linear load, pier settlement, pier rotation, temperature and the earthquake has been performed. Non-linear behaviour has been assumed for the materials. The finite element code ANSYS has been used for analysis. The Willam-Warnke failure criterion has been used for brick masonry. The case of equal heights of konus and vaults of the structure has been the most favourable case. The settlement of the middle pier has been the most inappropriate case and the structure has failed quickly. For different cases of pier rotation, the pointed arch has had a better performance than the semi-circular and four-centred arches. For the temperature, the induced displacement in the pointed arch has been more than other arches. Under different states of earthquake analysis, all structures have been failed. Konus are the starting points of cracking and they always contribute to the failure mechanism. © 2020 Elsevier Ltd
Intelligent Buildings International (17566932) 9(4)pp. 222-236
In this article, an intelligent method to detect, locate and quantify structural damages is presented via an optimization model. To predict the damage location and severity, the theory of pseudo-residual force vector (RFV) is applied. The proposed method can identify damages based on only a few mode shapes of the structure that can be easily obtained by a dynamic test. The objective function is defined as a minimum difference between the numerical and experimental variables in the RFV and the gravitational search algorithm is employed as a meta-heuristic technique for solving this optimization problem. The efficiency of the proposed method is investigated through the numerical examples with different damage scenarios. In the examples, the experimental data were simulated numerically using a finite element model of the structure and as demonstrated, it is possible to identify the damages with a reasonable level of accuracy while considering noise effects. © 2016 Informa UK Limited, trading as Taylor & Francis Group.
Journal of Performance of Constructed Facilities (19435509) 30(2)
In this paper, the structural behavior of nine historical brick masonry minarets in Isfahan, which were built in the eleventh and twelfth centuries A.D., against weight, temperature, wind, and earthquakes is studied. A nonlinear three-dimensional FEM has been used. To investigate the effect of the central column and spiral staircase on the structural behavior, analyses have been performed for two cases: (1) the complete minaret, and (2) only the outer shell. The structural analysis of minarets under temperature changes shows that for certain inner and outer temperature differences, the minarets fail. Minarets do not fail because of the maximum wind velocity of Isfahan. All minarets fail when subjected to imposed earthquakes. By decreasing the minaret height or increasing the material strength, failure is delayed. Changing the failure criterion or damping ratio has little effect on the failure of the minarets. © 2015 American Society of Civil Engineers.
Proceedings of the Institution of Civil Engineers: Structures and Buildings (09650911) 168(6)pp. 387-401
The structural behaviour of semi-rigid composite connections with a partial depth end-plate and precast hollow core slab was investigated by studying moment–rotation diagrams, rotation and bending moment capacities, and induced stresses. The variables considered were the size of the steel beam, the thickness of the lower flange of the beam, the size of column, the number of longitudinal rebars of the concrete slab, and the thickness of the partial depth endplate. A parametric study was undertaken using the non-linear, three-dimensional, finite-element method, with monotonic loading applied to connections. The results obtained indicate that the thickness of the partial depth endplate has a great effect on the bending moment capacity of the connection. When the beam size was varied, three failure modes were observed. The variation of beam depth had the greatest effect on the bending moment and rotation capacities. Reduction of the beam lower flange thickness considerably affected the rotation capacity and changed the failure mode in the connection. When the number of longitudinal rebars was increased, the bending moment capacity increased but the rotation capacity showed a slight decrease. For the column, the variation in web thickness had the largest effect. It was shown that it is possible to use a simplified method to predict the bending moment capacity of a semi-rigid composite connection. © ICE Publishing: All rights reserved.
Journal of Asian Architecture and Building Engineering (13472852) 7(2)pp. 239-245
Today the cultural heritage of humankind is endangered not only by natural catastrophes and the exploitation of resources but also by economic and social problems and institutional weaknesses. Western and Central Asian countries contain a major part of the cultural heritage on the earth, but due to different problems common in developing countries, cultural heritage in such countries suffers from natural and non-natural risks. A lack of public awareness of various types of risks itself worsens the conditions in such countries. It is necessary to clarify the situation within the region regarding different categories of risk, and then considering how to devise measures for heritage sites that are truly endangered at present, as well as how to prepare for risk anticipated in the future. This paper discusses and categorises the risks to cultural heritage in Western and Central Asia.
International Journal of Design and Nature (17443679) 1(2)pp. 186-196
The climatic characteristics in different regions of Iran have created architectural design problems. It is advantageous to look at various architectural solutions to such problems. In the hot-dry climate of the indigenous settlements of Iran, particularly interesting design solutions are found. Most solutions, such as high thermal capacity construction materials, compact structure of cities, narrow winding passageways, thick walls, courtyards, internal vegetation, arched roofed chambers, highly elevated wind towers and big water reservoirs, are in conformity with nature and environment. The role of architectural elements is to make use of natural forces such as light, heat, wind and water in design. In this paper, the effects of climatic factors on urban and architectural forms in the hot-dry regions of Iran, climatic design problems and architectural solutions are explained.
Journal of Structural Engineering (07339445) 132(11)pp. 1801-1805
The wooden columnar structure of the historical building of Ali Qapu in Isfahan is a notable sample of Iranian traditional construction of 350 years ago. In this study, the structural system and load carrying elements of the structure have been identified. Structural analysis due to applied loads has been performed and structural strength of its members has been examined according to related codes. Based on obtained results, suggestions for reinforcement of the structure have been made. In this paper, the results from study on the wooden columnar structure of the Ali Qapu building are presented. © 2006 ASCE.
Building and Environment (03601323) 40(10)pp. 1413-1427
Nature displays profound preference for certain specific ratios to design her life-forms. These are geometric relationships that are transcendent and originated from Sacred Geometry. The view that geometry had a ritual origin is a part of a wider view that civilisation itself had a ritual origin, and therefore the history of utilisation of Sacred Geometry by man goes back to many centuries ago. The Pythagorean tradition, and the Egyptian and Babylonian sciences from which it derived, and Persian mathematics, a part of which reflects a Pythagorean intellectuality, are based on the sacred conception of numbers and their symbolism. In the traditional world, geometry was inseparable from the other sciences of the Pythagorean Quadrivium, namely arithmetic (numbers), music and astronomy. Traditional geometry is related to the symbolic configurations of space. Geometric forms such as the triangle, square and various regular polygons, the spiral and the circle are seen in the traditional perspective to be, like traditional numbers, as aspects of the multiplicity of the Unity. Architecture itself has always had a sacred meaning to all traditional civilisations through millennia, by which means man has tried to provide for himself a manifestation of heavens. Persian architecture always emphasised on Beauty, and by means of Sacred Geometry Persians measured the proportions of heaven and reflected them in the dimensions of buildings on the earth. A comprehensive utilisation of proportions in Persian architecture, such as in the design of plans, elevations, geometric and architectural patterns, and mechanical and structural features, can be proved through geometrical analysis of Persian historical buildings. In this paper, the sacred conception of geometry and its symbolism in the Pythagorean tradition, and Sacred Geometry and proportions in natural life-forms will be explained. The use of the science of geometry in design of a number of Persian historical buildings will be presented. The geometric factors upon which the design of these buildings, from both architectural and structural viewpoints, is made will be discussed. © 2004 Elsevier Ltd. All rights reserved.
Advances in Architecture Series (13681435) 20pp. 503-512
The use of wood as a building material in Iran has a long history which dates back to the first millennium. At that time wood was used to make the roofs, beams and columns of some buildings. The extensive use of wood in the construction of large wooden buildings came into practice in the seventeenth century A.D. In that era, huge wooden structures were introduced to the world, some of which are still in existence. A typical example of such buildings is the wooden structure of the Ali Qapu building in Isfahan, Central Iran. The main part of the building, which supports the wooden structure, is made of masonry materials and it was repaired and maintained in the 1960s, but the maintenance of the wooden part remained incomplete. In 1987, a thorough study of the structural behaviour of the wooden structure was completed. Instructions were proposed for repairing the structure according to this investigation. This paper demonstrates the maintenance procedure of the whole building and, in particular, the study of the wooden structure, and it presents instructions for maintenance of the wooden structure.
Institute of Physics Conference Series (09513248) 180pp. 25-34
Geometry has a ritual origin and utilisation of Sacred Geometry by man goes back many centuries. Certain specific ratios can be found in the design of lifeforms in nature Traditional civilisations regarded architecture as a sacred means by which the heavens were manifested. Persian architecture utilised proportions comprehensively and by means of Sacred Geometry measured the proportions of heaven and reflected them in the dimensions of buildings on Earth. In this paper, the design of a number of Persian historical buildings by the use of the science of geometry will be presented. The geometric factors upon which the design of these buildings is made, from both architectural and structural viewpoints, will be discussed and common design laws between Persian monuments and creatures in nature will be explained.
Advances in Earthquake Engineering (1361617X) 13pp. 157-165
Iranian traditional domes are of the most notable samples of traditional construction in Iran spanning thousands of years, many of which have been standing on seismic parts of the country for many centuries. Structurally, Iranian domes can be categorised into single, double and triple-shell domes. Single-shell domes are the earliest type of domes. The single-shell is the main load bearing part. Double-shell domes consist of two shells, and they are divided into continuous and discontinuous types. In continuous double-shell domes the distance between the two shells is small and shells are connected by brick connectors. In discontinuous double-shell domes there is a considerable distance between the two shells. For the structural stability of some domes meridional walls or stiffeners are built in the space between the two shells. There are also a few domes with three shells. In this paper, structural systems of a number of Iranian historical domes made of masonry materials will be discussed and their structural strength and stability due to dynamic effects of earthquakes will be presented. The document will also explain the structural role of meridional stiffeners in double-shell domes.
