JOURNAL OF STRUCTURAL AND CONSTRUCTION ENGINEERING
Year:2021 | Volume:8 | Issue:4|Papers Count:18

The construction of segmental precast concrete bridges is an increase due to its superior performance and economic advantages. This type of bridge is appropriate for spans within 50 to 250 m, known as mega-projects and the design optimization would lead to considerable economic benefits. In this study, a box-girder cross section of bridge superstructure with balanced cantilever construction method is assessed. The depth of cross section, thickness of top and bottom flange, thickness of webs and the count of strands of pre-stressed steel are considered as design variables. The optimum design is characterized by geometry, serviceability, ductility, and ultimate limit states specified by the American Association of State Highway and Transportation Officials (AASHTO) standard and AASHTO Load and Resistance Factor Design (LRFD) specifications. Genetic algorithm (GA) is applied for cost and weight optimization. To validate functionality of this algorithm, a real bridge constructed in the city of Isfahan, Iran (Esteghlal Bridge, completed in 2017) is optimized as a case study. The total of a 13% reduction in cost and weight of the bridge superstructure is observed. The cost optimization algorithm is run by considering different spans and relation between superstructure cost and span length is assessed. The efficiency of applying the GA in optimization of this kind of bridges is proved.

One of the most important manifestations of sustainable development in any country is the country's productivity of sustainable sources of income. In fact, sustainable income is the basis for sustainable urban development. In the current century municipal financing is one of the most important issues in urban management, and in our country there has always been a discussion and a place for the challenge. Accordingly, in this paper, the aim of presenting an optimal model for sustainable municipal income for construction projects is based on the use of decision-making methods and calculation of the parameters of effective parameters in the assessment of sustainable earnings in the municipality of Karaj city. In this regard, Delphi method was used to validate the validity of the questionnaire using SPSS software. Therefore, the criterion of Evaluation, judgment by a group of experts and based on completing the questionnaire and conducting interviews with accurate experts in providing financial resources and urban management. The ranking of effective measures in assessing income municipalities using the Hierarchical AHP technique was done in Super Decision software and language quantitative meter using the method the average FOWA weighted weight has been paid to prioritize earnings resources. Based on the findings of the research in the city of Karaj, among the sources of income studied by the FOWA method, it can be seen that the transitional tax option from the government to the municipality using the AHP method with a coefficient of 0/150 and in Riskiness with a coefficient of 0/166 and risk aversion with a coefficient of 0/144 with 9 indicators of the highest priority in the assessment of the supply of municipal resources for the sustainable growth of development projects.

The high depth created favorable space for placing the openings which are to provide some capabilities such as mechanical and electrical installations, but these openings reduced load bearing capacity of the beams. One solution to the mentioned shortcoming is to use FRPComposite sheets; the effect of FRP-Composites in improving load bearing and ductility of concrete members such as columns and beams is approved in previous investigations. This study utilizes the CFRP sheets to compensate for weakness arisen from the created openings. To this end, 5 deep beams with 10x50x120 cm dimensions, each having two circular openings with 20 cm diameter placed in symmetrical order, are constructed and undergone a three-point monotonic bending. The Externally Bounded Reinforcement (EBR) and Externally Bounded Reinforcement on Grooves (EBROG) methods have been utilized to install the FRP sheets in two configurations being wrapped around and inclined. The results have shown the superiority of EBROG method as well as the efficiency of the inclined orientation of strengthening sheets in increasing the load bearing-capacity. Also, Shear failure was the type of failure in beams and it has been observed that generally, diagonal cracks, which lead to the strut formation, tend to be formed in the beams. The cracks started from the support plates and propagated towards the loading plate. In addition to the extended cracking, the strengthened specimens have experienced debonding and failure in their composite strips. The strengthening strips have experienced failure in the wrapped specimen as a result of providing suitable confinement and leaving no chance for strip debonding as well as in the specimen with inclined strengthening strips as a result of the high efficiency of tensile stresses on the strips. Compared to the related non-strengthened specimens, the load bearing capacity increase arising from inclined orientation is 40% to 43%. In addition, this amount compared to the wrapped around specimen is about 16%.

Seismic sequence as a result of occurrence of strong and moderate earthquake ground motion in a short time strongly affects the seismic response of structures. This kind of excitation causes, in many cases, more deteriorated effects compared to the corresponding single ground motion. The aim of this paper is to investigate the effect of seismic sequence of earthquake ground motion on the seismic responses of steel moment frame structures considering soil-structure interaction (SSI). To this end, four steel moment frames with 8 and 16 stories are considered each of which have three and six bays. Soil-structure-interaction is considered by employing dampers and springs having specified damping and stiffness through cone method. For modelling SSI effects, three types of soil based on standard 2800 are considered. The time history of responses show that the relative displacement of structure is increased when the structure is subjected to the seismic sequence. As a result, the damage induced to the structure. It is noteworthy to say that the effect of seismic sequence is more in soft soil. The obtained responses show that a special attention should be paid for designing of steel structures in high seismic zone when they are subjected to seismic sequence excitation. Furthermore, soilstructure-interaction is an important parameter that should be considered for such conditions. Therefore, it is recommended that the effects of seismic sequence and soil-structure-interaction should be accounted for better estimation and evaluate accurate responses of steel shear frame.

By increasing the height and slenderness of tall buildings, the windinduced dynamic response especially crosswind response becomes the governing parameter in the occupant comfort requirement of tall buildings. In the present study, crosswind response of tall buildings has been investigated using the frequency domain analysis of multi-degreesof-freedom systems based on the random vibration method. The tall structure has been modeled as a vertical cantilever beam with the masses lumped at the nodes. All the modeling and analysis procedure, including element meshing, determining the transfer matrix, calculating the matrix of crosswind force spectrum, and the numerical integration to obtain the root-mean-square (RMS) displacement and acceleration responses are carried out using MATLAB software. The effect of different parameters, such as basic wind speed, aspect ratio, side ratio for rectangle section and top to bottom width ratio for tapered tall buildings has been investigated. The results show that the slenderness ratio has an important role on the across-wind response. For tapered buildings, the crosswind displacement response decreases considerably with increasing the top to bottom width ratio. For the studied tall buildings, the crosswind acceleration response is higher than the occupant comfort level and it requires to be reduced using an appropriate control strategy.

In this research, the co-operation of steel and concrete in composite columns is considered. Using numerical modeling to study the behavior of these sections, a new type of composite sections named concrete-filled double-skin steel column is introduced. The factors affecting numerical simulation, which bring this simulation closer to the laboratory conditions, determine the axial resistance of the samples by changing the dimensions and geometry as well as the properties of the materials. The purpose of this thesis is to investigate the effect of concrete compressive strength on the axial performance of concrete-filled double-skin steel column CFDST concrete. A total of 20 samples with different parameters such as effects of concrete, loading capacity and width to thickness ratio on the strength of columns with square and round cross section in inner and outer walls were investigated by ABAQUS software. The results of the study showed that the loading capacity of CFDST columns under axial pressure increased by about 4% with increasing compressive strength of concrete in the inner wall. Also, studies showed that with increasing cross-section in the inner wall, the loading capacity in square columns increased by about 7% and decreased by about 3% in circular columns.

Concentrically braced frames (CBFs) have become prevalent as a lateral load resisting system due to their rigidity, low lateral displacement and ease of implementation over the last three decades. These advantages encourage the increasing utilization of this system in the construction industry. Despite the advantages of CBFs, the lack of ductility and buckling of the bracing element before yielding is the main disadvantage this lateral system. In the last three decades, studies have become focused on the ductility and energy dissipation of the CBFs that were modified in terms of using dampers and fuse segments. The current study aims to presents an innovative Composite Buckling Restrained Fuse (CBRF) to be used as a bracing segment. CBRF with relatively small dimensions is an improvement on Reduced Length Buckling Restrained Brace (RL-BRBs) as a hysteretic damper with different performance in tension and compression. Extra tensile elements in a novel configuration were used to compensate for the limitation of tensile strength that exists in bracing elements containing ordinary fuse segments. Here, some key design parameters of CBRF such as length and cross-sectional area of the core are discussed theoretically. Two specimens were designed and tested under cyclic loads. Moreover, the hysteretic response of the specimens was evaluated to calculate their strength adjustment parameters. The results indicate that the proposed CBRF has a ductile behavior with an average strain of 5% and high energy absorption capacity along with sufficient tensile strength.

Recently, base isolation techniques are applied as a resisting system to protect the structures from seismic and dynamic loadings. Due to their importance, in this paper, an optimum arrangement of lead rubber bearing (LRB) and friction pendulum system (FPS) is investigated in irregular buildings and its performance is compared with a regular case. For this purpose, 3 types of irregularities have been adopted. Accordingly, 3, 7 and 10 story buildings have been performed and 12 possible combination have been applied for the isolators in each model. Afterwards, the numerical models have been analyzed using nonlinear time-history analysis and direct integration method and applying 7 earthquake records along the longitudinal and transverse directions of the building. The obtained results of the numerical study show that the application of FPS and LRB isolators in outer and inner columns respectively, led to a better performance compared to the other arrangements by reduction of the inter-story drifts as well as base shear and enhancement of the energy dissipation which is due to the characteristics of FPS isolators in balancing the applied forces with the building’ s mass and prevention of torsion occurrence in irregular structures. Unlike the irregular buildings, application of FPS and LRB isolators in inner and outer columns, result in a better performance by reducing the story drifts in regular structures.

Economic tools are definitely an effective way to encourage or enforce contractors to enforce environmentally-friendly practices. Previous studies on this subject mainly focus on the management of waste of construction and demolish (C & D) from the static point of view, which does not take into account the nature of its dynamic by taking all necessary activities in the waste chain. Therefore, the purpose of this paper is to explain the dynamics and relationships between the components of C&D waste management and to analyze the costs and benefits and cost of transportation and fuel consumption using the system dynamics approach. The findings show that the implementation of C&D waste management has many benefits, but the higher cost of landfill at authorized sites will result in more net profits, which will be accompanied by disadvantages such as environmental damage. In addition, the public is suffering from landfill in unauthorized locations and imposing environmental costs due to illegal evacuation. Simulation results also show that increased landfill in unauthorized locations increases fuel and energy consumption and therefore increases fuel consumption costs. This study by investigating and evaluating the researches and measures taken on the waste and waste spillway aims to clarify the use of a systematic approach using the dynamics of systems in a direction in which it is possible to use contract cost-benefit analysis to encourage contractors to disposal of Construction waste in a way that is conducive to the development of the building industry and the preservation of the environment and the resulting savings.

Concentric bracings (CB) are one of the most prevalent lateral load bearing systems in steel structures. These bracings have a remarkable lateral stiffness and strength, but their compressive buckling prevents them from being ductile and absorbing optimal energy. Consequently, in recent decades, researchers have conducted extensive studies to improve the concentric bracing behavior, which resulted in the development of different design and execution methods for concentric bracings. In this paper, by using numerical and experimental studies, a new method is proposed to improve the behavior of concentric bracings. In this method, a local fuse (LF) is used along the brace. This fuse is restrained by auxiliary elements (AE) to prevent its local buckling under compressive load. This makes the brace behaves in a similar manner in both tensile and compressive cyclic loads, resulting in ductile behavior and highenergy absorption. In this study, by using numerical results, an investigation is done for proper position of the fuse along the braces and its optimal shape and length. In addition, an analytical study has been performed comparing the structural behavior of concentric braces with LF-AE braces. The results have been demonstrated that LF-AE braces have better performance than concentric braces.

Nowadays, one of the newest studies in the field of structure engineering and earthquake is the acquisition of systems that will quickly return to pre-earthquake and service after an earthquake. Thin steel plate shear walls in reinforced concrete frame with replaceable as a sacrificial member or fuse will protect the sidewall system during an earthquake. In this paper, a method performance-based plastic design in a reinforced concrete frame with a thin steel plate shear wall on the dual behavior caused by the interaction between the frame and the wall is presented. This design method is a non-repetitive, simple, and programmable method by which the structure is designed with the proper levels of performance for different purposes. Target Performance Levels In this paper, the elastic behavior in an service earthquake for uninterrupted usability, nonelastic behavior of the plate and elastic behavior of the bending frame in an earthquake design for quick reconstruction and non-elastic behavior of the total structure in a maximum earthquake to prevent collapse. For this purpose, three structures, short, medium and high (6, 12 and 18 storey), were designed In the high seismic region with this method. Nonlinear dynamic analysis is performed on these structures using the strip model in OpenSees software. Results were compared with the values of ASCE7-10 and other proposed values of the researchers, and a suitable matching was observed. Based on the results of the analysis, it was determined that the structures designed at three levels of assumed hazard have reached the target performance levels.

Structures are subjected to different kinds of loads during their lifetime, such as those caused by daily temperature swings, traffic loads, abrasion and severe loads like earthquake. The occurrence of damage in building structures, oil platforms, and generally all structural systems is inevitable. Different kinds of failure in various engineering structures have been observed so far, which have incurred massive financial losses and serious casualties. Most of such damages could be identified with structural condition assessment, and therefore crack propagation in and total collapse of the structure can be prevented by taking rehabilitation measures. The fact that in seismic prone regions where the occurrence of minor and local damages could lead to the total collapse of the structure increases the importance of structural health monitoring substantially. Hence, determining the damages in structures in order to monitor structural health, increase the safety of the structure, and determining the current condition of the structure seems vital. In this research, spectral strain energy is considered as an index for determining the location of the damage. By making a comparison between the spectral strain energy of healthy structure and damaged structure, damaged elements can be identified. In addition, the capability of the aforementioned method in the linear and nonlinear regimes will be assessed. To demonstrate the efficiency of the adopted procedure, numerical examples are provided whose results indicate precision and suitable performance of the proposed method in identifying damages in structures.

Investigation and evaluation of damages to surrounding structures and also estimation of rupture levels by considering the amount of deformations and the amount of adjacent gates are important issues in the nailing system in urban areas. In this research, we tried to evaluate the axial force of the nails and the deformation in concave and convex dams; in sandy and clay soils. In this regard, numerical modeling is carried out using the Abaqus CAE software in the soil environment and parametric studies are carried out for different corner angles in the excavation under the service load. The results of this study indicate the effect of concave cortical deterioration and the damaging effect of the convex corners, which is in contrast to the concave hedge, in gondolas with sandy soil as well as clayey soil. The maximum axial force of the nails in the clay soil is less than that of the sandy soil, which decreases with the approach to the hollow corner. For maximum seating and horizontal displacement of the Goodwall wall, there is also a turning point between the angular angles of 130 ° to 150 ° , with a good turnaround. By comparing and analyzing land surface levels and rupture levels, we will find that the maximum level of earth's summation in sandy soils will be the highest level of rupture, and in clay soils, ground-level landings in the location of critical burst surface changes It is noteworthy.

One of the most interesting topics in the geotechnical and geophysical engineering is the use of surface waves to characterize the earth subsurface layers. In a vertically heterogeneous media, the phase velocity of the surface wave is a function of the frequency (the frequency-phase velocity relationship is called dispersion curve). The dispersion curve is calculated by the shear wave velocity, compressive velocity, density, and thickness of each of the layers, which their properties can be increasing or decreasing from the surface to the half-space. In this paper, horizontal soil layers were modelled using finite element method based software (ABAQUS). Due to the different layering specifications, the models are divided into two main types: the layers’ characteristics increase with depth and the layers' characteristics decrease and increase with depth. An active impact source was used to create surface waves and the absorption layers with increasing damping (ALID) were applied to the model boundaries to prevent the wave reflection. Based on the gathered surface wave data, the dispersion curve was plotted using Frequency-Wavenumber Transfer method. In addition, the effects of different geophone offsets on the dispersion curve were investigated. The results showed that using the dispersion curve and phase velocity at high frequencies, the thickness of the surface layer can be calculated. Also, the slope of the dispersion curve at low frequencies indicates the number of the layers at different properties, and the steeper and closer to the vertical, means that a few number of layers are exist in the media. Furthermore, the effects of different geophone offsets were investigated and it was observed that geophone offsets should be limited to less than one-fourth of the layer depth in order to prevent the dispersion curve jumping to the higher modes. Furthermore, if the dispersion curve jumps to the higher modes at high frequencies, seismic data can be taken at a less geophones’ offset or the dispersion curve frequency range limitation is only before jumping to higher modes.

Coupled steel plate shear wall consist of two shear wall with flat web plate with rigid beam-column connection, that connected with coupling beam at story level. Coupled steel plate shear wall consist of two panels with rigid beam-column connection, that connected with coupling beam at story level so its possible to use opening in wall. In this study, two types of six story steel plate shear wall with coupling beam with trapezoidally corrugated infill plate designed with performance plastic design method and two other types designed with force base design. All models have been designed in ABAQUS software and the software outputs were compared and verified by the behavioral mechanism of uncoupling shear wall of the trapezoidal corrugated sheet and the shear wall of the flat web sheet. Subsequently, these four samples were analuzed with time history analysis with the three Northridge, Kobe and Tabas earthquake records. Investigated output of this study consist of relative drift at the peak of maximum displacement of each records and residual drift. With the result of these four models figure out that relative drift are in allowable drift ratio (2%). But each design procedure has advantages than the other one. Advantages of performance plastic design in comparison with force base design are consume less steel material and distribute uniform relative drift ratio. While the advantages of force base design has less relative drift ratio. Hence, in frames which designed by force-based design in comparison with performance based plastic design has less residual drift.

Between various sectors of civil engineering, concrete is one of the most widely used materials in the building industry. The use of pozzolanic materials is one of the solutions for high strength concrete production. High-strength concretes have high compressive strength, high adhesion, very low w/c ratio and permeability and therefore high durability. In this study, zeolite and nanosilica were used as natural and synthetic pozzolans. At first, concrete samples with 20 mixing designs (included water, cement, fine and coarse aggregates, zeolite, nanosilica and superplasticizer) were designed to achieve the optimal design, and then tests of compressive strength and permeability of high-strength concrete were carried out. In the final step, the values of the mixing plan with the compressive strength results are used as inputs of the neural network. Then, the proposed relationship is optimized using the optimization algorithm from an economic perspective (optimal component value). The addition of zeolite and nanosilica to concrete not only increases resistance, but also decreases the permeability of samples, especially in the long term respect to pilot samples. According to the optimization results, it is observed that cement and nanosilica content has been reduced due to the high cost of production, but increased on zeolite values.

In this paper, a modal pushover method is introduced for the assessment of the asymmetric-plan buildings in which, a load pattern is derived based on the story shears and story torque of building due to the simultaneous excitation in x and y directions. The proposed method is a single-run procedure and its significant advantage is its capability in consideration of the structural yielding in one direction on the total responses of the structure due to the simultaneous excitation in two orthogonal directions. In this method, in order to consider the instantaneous changes during the pushover analysis, two capacity curves of the structure are established based on the adaptive capacity spectrum method and the target displacement corresponding to each capacity curve is determined. Then, the structural responses at two pushover steps corresponding to the obtained target displacements are obtained. Eventually, the total responses of the structure are computed by combining the responses corresponding to the x and y directions. In order to evaluate the proposed method, this method has been applied to an irregular 20-story building subjected to the seven pairs of ground motion records and the obtained results are compared with the responses of nonlinear dynamic analysis as the exact responses. The results show the high accuracy of the proposed method in estimating the inter-story drifts of the studied building.

Housing is one of the major needs. The use of new and new technologies to increase the speed of construction, improve quality, increase earthquake resistance, increase the useful life of buildings is more than ever before. In this paper, four building methods Including LSF, LCF, 3DPANEL and PRCS, 12 criteria for timely delivery of credit, ease of implementation, need for expert workforce, availability of consumable materials, control and supervision in the process of implementation, useful life, cost, quality Maintenance, energy saving, reducing dead load, increasing floors, compliance with regulations that, from the point of view of contractors, employers, And project consultants. These criteria have been selected using the Delphi method from among the selected criteria, and the fuzzy and gray vikor method has been used to rank building methods, to collect information from seven companies The contractor, two consulting companies and a number of professors have been used to obtain information. Regarding the ranking differences of the methods of construction in both fuzzy and gray vikor methods, for the final ranking of the ranking method, which includes the mean rating method, the Breda method and the Copland method, was used. For the results obtained The best way to build PRCS is through the LSF and 3D-PANEL methods, and finally the ICF method.