نشریه مهندسی سازه و ساخت
سال ششم شماره 3 (پیاپی 26، پاییز 1398)

I am glad to announce publication of Volume 6, No.3 (2019) of Journal of “Structural and Construction Engineering”. Journal of “Structural and Construction Engineering” publishes by Iranian Society of Structural Engineering (ISSE) which is one of the leading institutes in the region. ISSE’s mission is to create an appropriate platform for the purpose of scientific, technical, research, educational communication, and scientific exchanges and competitions between researchers and specialists in structural engineering and related fields, and integration of the activities in the field of structural engineering and construction, the expansion of the frontiers of science and professional and public awareness in MEA region. To do so, ISSE established a leading journal and will publish it four times a year.
Journal of “Structural and Construction Engineering” provides a forum for a broad blend of scientific and technical articles to reflect the evolving needs of the structural engineering and construction communities in the region. The scope of “Structural and Construction Engineering” encompasses, but is not restricted to, the following areas: structural engineering; earthquake engineering; structure-soil interaction; structural fire engineering; blast engineering; structural reliability/stability; life assessment/integrity; structural health monitoring; structural dynamics; experimental modelling; performance-based design, construction management. “Structural and Construction Engineering” also publishes review articles, technical notes, and a diary on national and international events related to any aspect of structural engineering.
“Structural and Construction Engineering” has a continuous open call for papers. Backed by the reputation of the members of its Editorial Board, we will continue to push for excellence in the contents and quality of this journal. From now on, all published articles in JSCE will get Digital Objective Identifier (DOI) which is very important for indexing and etc. In addition, JSCE is an Open Access (OA) journal that is available online to the reader without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. We also are proud to announce that Ministry of Science, Research and Technology of Iran gave grade A to JSCE (similar grade to ISSE) in the last year evaluation.
I wish you enjoy reading this issue of “Structural and Construction Engineering” and I invite you to contribute to the success of this journal by submitting your articles.

Increase of impervious surfaces in urban areas, has led to many problems, including flooding roads and streets during rainstorms which could create difficulties for pedestrians and cars. An effective way of reducing urban runoff and waterlogging is to use permeable concrete pavement. In the present study, the effect of replacing different percentages of travertine additive with the main aggregates of permeable concrete on physical and mechanical properties of this type of concrete has been studied. Samples development and testing with three replicates for each sample was carried out at the Concrete Technology Laboratory of Semnan University. Statistical analysis of the results was carried out using SAS 9.4 software at 95% confidence level for all the samples. Results showed that due to the porous structure of travertine, increasing the percentage of travertine replacement with aggregate increased the porosity and permeability coefficient. The highest porosity was observed for T-100 and T-75 specimens, which was 29.13% and 28.78%, respectively. Also, the highest permeability coefficient (1.96 mm/s) was for T-75 and T-100 specimens. Other results indicated that replacement of travertine with a percentage of aggregates in porous concrete reduced the compressive strength of the samples compared to the control sample. Maximum and minimum compressive strengths were 17.33 and 12.22 MPa, respectively, for T-25 and T-100 specimens; While the compression strength of the control sample was 18.45 MPa. Based on the results, due to porosity, high permeability and suitable resistance of this permeable concrete with travertine , this type of concrete has high potential to be used in pavements, especially in areas with low traffic.

This paper evaluates the effect of I-shaped beams connection rigidity with different span length on vertical force and shear stress distribution in beam flanges and web at connection section in comparison with classical theory of stress distribution. Accordingly, 72 models with different connection rigidity under concentrated static load in mid span have been made for doing parametric study in ANSYS Workbench finite element software. The linear static analysis was done on all constructed models. Variable parameters in these research for parametric study include of connection rigidity in the case of change in the end plate thickness (from 7 to 30 mm), beam span length, restraint or no restraint between beam web and flange and the presence or absence of Poisson’s effects. Performed studies have shown that that vertical shear stress distribution in beam to column connection section with moment connection differs a lot from what is stated in mechanics of materials equations. Practically the available equations in regulations which state that web receives the entire vertical shear and ignore the contribution of flanges are not reliable. Studies also showed that the contribution of the flanges and web at connecting section from vertical shear force strongly affected by the connection rigidity and the beam span length. On the other side, the results express this fact that among desired parameters the existence of restraint between flanges and web in all models is the most important parameter in the differences between the classical and real results and elimination of this parameter in structures can be considered as an idea to improve the performance of the modern connections.

Project planning and scheduling are one of the most important issues in construction engineering and management. It is being crucial to progress developed countries. One of the major challenges in construction project management is time and cost management. The traditional view lonely is not able to meet the needs of this field. Therefore, the use of modern management approaches can be greatly helpful. Time and cost are among the important objectives of each project. Cost and time trade-off is among the major important issues in projects planning and control and the main of solving this problem is actually analysis of interaction of different types of project costs and time of the project. In this paper, a time and cost trade off project scheduling problem under budget constraint is studied. For this purpose, a meta-heuristic genetic algorithm is developed to find the optimal solution in MATLAB. Completion time sensitivity analysis is done according to different budget level. In order to validate proposed algorithm, problem is solved by GAMS and the outputs between them are compared. The results show that proposed meta heuristic algorithm is able to solve problem optimally so that differences between samples solution were zero in different budget level.

Deep excavation have a direct effect on stresses and strains of surrounding soil, and it leads to the change in static and dynamic response of adjacent structures of the excavation. In this study the effects of urban rail ramp permanent excavation on Hamyari response, has been investigated. Consideration of soil-structure-groove interaction has a great effect on the structure response, including increased range of internal motion of foundation and floors, reducing the base shear, and increasing the natural period of the structure. The three-dimensional study has considered a nonlinear behaviour for soil and steel materials and also, semi-infinite elements have been used for viscose boundaries. The use of semi-infinite boundaries has shown a desirable performance in seismic analysis of soil environments. Placement of the building near the entrance ramp of Kermanshah metro and consideration of soil-structure interaction near the excavation, lead to the 8.98% increasing in the first period of the structure, decreasing 19.37% base shear of the Structure against the rest rigid condition, and also increasing the lateral displacement of floors, especially higher floors, and this increment in the roof floor compared to the rigid base and soil-structure interaction are 89.89% and 14.25%, respectively. Also, consideration of soil-structure interaction adjust excavation for building compared to the case with soil-structure interaction and without the excavation effect, leads to the 1.09% increasing in the first period of the structure and 10.27% decreasing in base shear, and also increasing of acceleration response spectrum.

The use of externally bonded fiber reinforced polymer (FRP) has been proven to be an effective and efficient method to strengthen deficient concrete components and structures. This paper presents numerical investigations on the de-bonding behavior of concrete beams strengthened with externally bonded CFRP fabrics, at elevated temperatures. The numerical study was carried out, using the commercial package, “Abaqus”, for finite element analysis. The simulation was validated against laboratory four point bending tests of nine plain concrete beams previously performed by the authors. The behavior of concrete beams with three different design concrete strength of 20, 30 and 40 MPa which were externally bonded by CFRP fabrics were investigated at -20, +20, +50 and +80 Degree Celsius. Linear elastic isotropic and orthotropic models were used for the CFRP layer and a cohesive bond model was used for the concrete – CFRP interface. A plastic damage model was also used for the concrete. In the finite element analysis, similar to the laboratory tests, the specimens were first heated up to the elevated temperatures, and then loaded up to failure. The results show good agreement with the experimental data, regarding the failure loads, load–displacement response, and crack patterns. The finite element results of thermal strains in CFRP and stresses in the concrete are also compared with the thermal strains and stresses, determined by the analytically models.

Water tanks are among the main components of water supply networks for storing, maintaining and supplying pressure, and these structures should have the ability to exploit and supply pressure in the water supply network after the earthquake. In this paper, the effect of foundation concrete hardness to tank concrete hardness on seismic analysis of air tanks has been investigated. In the current seismic analysis, the relationship between the concrete hardness of the foundation and the concrete of the tank body is expressed by the definition of the constant coefficient K. By changing this coefficient, its effect on each of the tensile/compressive stress, and displacement parameters using a probabilistic analysis is examined. The tank is modeled using a three-dimensional finite element method based on ANSYS software. In this model, the interaction between the tank body, fluid and foundation are considered and the accelerogram of Manjil earthquake in the intended model is used to apply the earthquake. The probabilistic analysis used in this study is Monte Carlo simulator using the Latin hypercube sampling method and K coefficient is used as an input variable. The maximum horizontal displacement of the structure, the maximum 1st principle stress and the maximum 3rd principle stress are selected as critical responses and output variables. The results of analyzing models and comparing responses such as maximum principle stresses and maximum displacement show that with regard to economic considerations and the appropriate reliability coefficient for the system, the most efficient and optimal value for the coefficient K is approximately 0.7.

One of the methods of resisting to earthquake forces and its undesirable effects on structures is the use of seismic isolators. Investigations on the seismic structure have been initiated by researchers since decades, but so far no study has been done on the subject of this research. Therefore, in this study, the seismic behavior of an asymmetric slip structure with a moment frame system is affected by the horizontal component of the earthquake with Considering the effects of soil and structure interaction have been investigated. In order to achieve the main objective of the research, one, five, and ten stories irregular structures (40% irregularity) are considered with seismic isolator R-FBI located on type II, III and IV soils. Also, for irregular effect analysis, irregular structures of 20, 40 and 60 percent were compared to the regular model. In order to obtain the results of the research, the finite element method has been used with modeling of nonlinear materials and performing dynamic explicit analysis. The results of the study showed that, by changing the type of soil (in accordance with the 2800 Standards), the displacement and acceleration of the structural changes considerably. This change for the conversion of II to III soil was 87.2%, 36%, 4.1%, and in order to convert the soil II to IV, 19.1%, 3.1% and 30.7%, respectively, to change location of the upper storey of the structure is 1, 5 and 10 stories. Also, the acceleration of the upper storey of structures of 1, 5 and 10 stories for converting II to III are 2.18%, 3.2%, and 43.2% respectively, and in order to convert II to IV are 51.5%, 40.5% and 57.4% respectively.

Buildings in high seismic regions are prone to severe damage and collapse during earthquakes due to large lateral deformations. The use of superelastic shape memory alloys (SMAs) as reinforcements in concrete structures is gradually gaining interest among researchers. the effect of SMAs as reinforcement in concrete structures is analytically investigated for 3, 6 and 8-story reinforced concrete (RC) buildings. Each building has five bays in both directions with the same bay length of 5m. For each concrete building, three different reinforcement details are considered: (1) steel reinforcement (Steel), (2) SMA bar used in the plastic hinge region of the beams and steel bar in other regions (Steel-SMA), and (3), beams fully reinforced with SMA bar (SMA) and steel bar in other regions. For each case, columns are reinforced with steel bar. Results obtained from the analyses indicate that the value of Sa in Steel-SMA frames are higher than SMA frames, and its recovery capacity is almost similar with SMA frames. the SMAs materials are expensive, and the use of Steel-SMA frames can be reasonably effective in seismic zones. The comparison between frames with various reinforcements details shows that Sa of 3-story frames with various reinforcements are almost identical. but, in 6- and 8-story frames, Sa of Steel frames are higher than others. frames with SMA bars in the all length or plastic hinge region of the beam have reached a same level of seismic demand under lower spectral acceleration which can be resulted from the decreased stiffness caused by SMA bars. results indicate that structural behaviour factor in 3 and 6 story buildings with different types of reinforcement is not much change, but this change is perceptible in the 8-story frame. In the case of residual drift in all cases, the use of shape memory alloys will reduce this drifts.

Structural elements exhibit cyclic behavior or hysteresis under seismic loads; therefore, the analysis of this type of response is of great importance in Earthquake Engineering. On the other hand, due to the complexity of this nonlinear behavior and the absence of an explicit function to express the restoring-force regarding deformation, the modeling and analyzing of the phenomenon of hysteresis is one of the most complex problems in nonlinear dynamics of structures. In this research, the modified energy method is used as a numerical method to analyze this type of systems. To achieve the objectives of this research, a brief review on elastoplastic hysteresis models is initially considered. Then, by formulating the energy equilibrium equations for single-degree freedom structures with nonlinear material-cyclic behavior, the computer-implemented algorithm of this method is presented in a step-by-step manner. A simple single-degree-of-freedom example with bilinear-elastic stiffness under free vibration using the proposed method is provided for the reader's familiarity with the concept of the proposed method. Subsequently, a one-story structure and a multiple-degrees-of-freedom system with elastoplastic behavior are analyzed using the given method, and conventional numerical methods are utilized to verify the results. In general, the results of this study showed that this method has a good accuracy compared to other techniques in the analysis of hysteresis behavior of structures. In addition, this approach decreases the order in the governing equation of the problem; and, there is no need to define the additional adjustable parameters in numerical solution. On the whole, the presented technique with simplicity in computer execution can be used by creating a physical sense in the analyst to calculate the response of hysteresis structural systems.

In this paper, in order to numerically model the bond-slip behavior of embedded bars, an applicable procedure was proposed. To evaluate the efficiency of the proposed model, a credible experimental specimen was selected and modeled in Abaqus software. Comparing the numerical and experimental results of the specimen confirmed the acceptable accuracy of the proposed model. Afterwards, two monolithic and precast reinforced concrete beam-to-column connections were chosen from experimental tests and were numerically simulated. Investigation on the precast specimen showed that the required embedded length of longitudinal bars of beam was not considered. Hence, slippage of the longitudinal bars of the beam at the connection area led to degradation of connection strength. In order to consider this slippage in finite element modeling, the proposed approach was employed. Analytical results showed a suitable agreement with experimental ones and slippage of the beam bars was observed in the finite element analysis. Consequently, in order to prevent the slippage of beam bars, couplers at the end of the bars were used. Required area of the couplers was calculated as such to develop yielding in longitudinal beam bars. These couplers were added to the precast specimen and afterward, this specimen was named modified-precast specimen. Capacity of the modified-precast specimen including yielding load, ultimate load and ductility was improved in comparison with monolithic and precast specimen. However, the ratios of ultimate moment to flexural strength in modified-precast and monolithic specimens are approximately equal to one, which shows the formation of flexural plastic hinge in the beams of both modified-precast and monolithic specimens.

In this article, the efficiency of Boundary Characteristic Orthogonal Polynomials (BCOPs) in analyzing the static and dynamic behavior of thin rectangular plates with openings versus the Finite Element Method (FEM) and the analytical solutions (if they exist), is investigated. Despite this simple procedure, according to the obtained results, the accuracy of BCOPs in most of the studied cases compared to the analytical solutions or those obtained via FEM is acceptable. Besides, different sizes for the openings are assumed and in one case a steel strip is used to stiffen the plate around the opening. Maximum deflection of the plate is the core parameter to be compared seeking the convergence rate of the employed method. Furthermore, natural frequencies of the plate are obtained and compared to assess the capability of BCOPs in dynamic analysis of thin plates. In all of the studied cases, the efficiency of the BCOPs is evident based on its simplicity in comparison with conventional FEM or other competitive methods. Furthermore, one of the main advantages of using these functions in comparison with eigenfunction expansion method in analytical and semi-analytical approaches in the analysis of thin rectangular plates is the existence of all plates’ shape functions for any arbitrary boundary conditions, while this is limited to some special cases in the exact eigen problem solution of the plate.

Extensive damages in a large number of existing buildings under in-plane shear has shown the need of structural strengthening techniques for masonry structures. FRP and shotcrete are strengthening techniques which can be used to repair or strengthen masonry structures. Masonry walls strengthened with FRP and shotcrete can greatly increase some behaviour parameters such as strength, energy absorption and stiffness, but the comparison and effect of single-faced FRP and shotcrete layers on shear behavior of masonry walls under lateral loads have not been studied so far. In this research in order to evaluate and validate numerical modelling approaches, two kinds of experimental masonry wall models made by clay bricks and concrete blocks strengthened by FRP and shotcrete were introduced. At the end, modelling and analysis of six walls under lateral loads using the nonlinear analysis of pushover in Abaqus software has been investigated. The results of the analysis show the feasible effect of strengthening unreinforced walls with single-faced shotcrete and FRP, so that the stiffness and strength of the wall increases significantly due to the addition of shotcrete to one side of the wall. Also, amount of energy absorption increase for FRP is 60-70% and for shotcretes 70 to 90%. Therefore strengthening by single-faced shotcrete has a more feasible effect.

In this numerical investigation, rectangular spiral reinforcement behavior have been examined. This article presents the finite element models of the experimental tests of 27 reinforced concrete beams that have rectangular spiral reinforcement with the distance of different vertical and horizontal leg angles. The explicit analyses have been verified the condition of confinement by changing in stress-strain curve of the reinforced concrete beams. According to the results of modeling, increasing the transverse reinforcement and improving in confinement advances the maximum torsion and more ductility of the concrete beams. Using continues rectangular spiral reinforcement in comparison with commonly used stirrups, with the same percentage of transverse reinforcement, improved the maximum torsion capacity from 5 to35%. In rectangular spiral reinforcement with various top angles, and the same percentage of the transverse reinforcement, increasing the top and side angles improves the maximum torsion. This improvement in torsion capacity is for the top angle of up to 20 degree. Exploring the results of rectangular spiral reinforcement that their top angles are not zero indicates that for the angles less than 14 degree, the results of maximum torsion have little deference with the ones having no top angle. Therefore, using rectangular spiral reinforcement with zero top angle is recommended. Its simple manufacturing and decreasing the cost of producing is considerable too.