نشریه مهندسی سازه و ساخت
سال هفتم شماره 2 (پیاپی 32، تابستان 1399)

Increasing energy consumption in the world raises concerns about future energy supplies. In addition, reducing energy consumption will reduce greenhouse gas emissions, such as CO2. Given that residential buildings have a significant share in energy consumption, reducing energy consumption in these buildings through the Building Management System (BMS) and insulation of their Exterior walls can have a significant impact on reducing energy consumption.In order to evaluate the impact of these factors on reducing the energy consumption of residential buildings, using Building Information Modeling process (BIM) with the help of BIM software is the method used in the present study. Using building information modeling process, after the modeling of the desired properties, the thermal analysis of the building has been done and by changing the parameters, the effect of each one on the energy consumption is investigated.The main objectives of this research is to investigate the effect of the use of thermal insulating materials and building management system on reducing energy consumption, comparing all types of thermal insulating materials in terms of type and thickness, comparing insulation and building management systems in terms of reducing energy consumption and finding optimal energy-saving model between different building models that have different conditions. Comparison in this study has been done between different building models and the actual base model. Finally, by doing the stated studies, the model with BMS system with 34.61% reduction in energy consumption compared to the base model has the most effect on reducing energy consumption.

In this study, damage detection methods of cable stayed bridges were investigated. Cable stayed bridges are flexible structures; meanwhile they are sensitive to vibrations due to their complicated and multiple vibrations modes; therefore, damage detection methods based on vibration data in cable-stayed bridges has become a challenging issue. In the present study, finite element model of Bill Emerson, Missouri cable stayed bridge was simulated in order to achieve a precise finite element model to simulate the damage scenarios in bridge and the study of them. General process includes four damage detection indices based on the modal data (mode shapes and natural frequencies) achieved by modelling structure and simulated damages and in each case the results of damage detection were presented by indices. These methods are: Enhanced Coordinate Modal Assurance Criterion (ECOMAC), Mode Shape Curvature (MSC), Modal Flexibility Index (MFI), Damage Index (DI). Some of the methods were applied in damage detection of the pervious structures and bridges. In this paper, correlative study of these methods were performed based on different damage scenarios as well as study of challenges such as different levels of random noise in the input data, incomplete modal data and low damage intensity in detection of damage in cable-stayed bridge and then, performance of the methods were assessed.

Near-field earthquakes have two important effects, Forward Directivity and Fling-step, in which Forward Directivity depends on the direction of occurrence of an earthquake, and Fling-step happens due to permanent displacement of the earth due to tectonic deformations and its integration with the tearing mechanism with a velocity pulse with high amplitude and a uniform step in the displacement time history. Considering that few studies have been done on the effects of fling-step on structures other than Forward Directivity, and also in most earthquake data centers, all earthquakes are filtered using filtering methods and the fling-step effect is eliminated, therefore, four types of 4, 8, 12 and 16-story structures are selected and are designed based on the American Seismic Code (ASCE-10), in accordance with the American Steel Regulation (AISC341-10), in accordance with all the criteria for steel special moment frames. 16 records having fling-step effect are selected and applied to the structures. Also, to show effect of neglecting the fling-step on the response of the structures, the same records having no fling-step are applied to the structures and compared to the unfiltered state. The results showed that fling-step has little effect on the structure response, and filtered records can be used on seismic analysis.

Nowadays traditional point of view is not able to meet the needs of construction project management. Therefore, the use of modern management approaches can be greatly helpful. The first step to reach this goal is to identify and verification variety of projects in terms of linear or network types, the difference in project and multi-project management, management and execute methods. In this research, critical chain management method is used instead of critical path method to provide more practical schedule. The proposed method solves a scheduling problem with time/resource tradeoff to provide a minimum-makespan deterministic schedule which will generally be a good starting point for project execution. Also to overcome the risk in the case, schedulers have a medium risk coefficient based on cognitive style. Anyway, the change of parameter β will give a little change in project duration. The proposed method is useful for both project planning and execution. The methods is simple, practical and can be easily computerized. It should be noted that although the advances in the field of computers and computing speed and information processing it is done, we still need to project manager and human using engineering vision, experience and knowledge can choose the best algorithm for each project to be felt.

The bridges with any form of structure that are designed and made with any kind of materials that are being manufactured, sooner or later, appear in their burnout effects, but in the type and extent of these exhaustions and their expansion, there are several factors such as conditions Atmospheric, flood or earthquake occurrence, increase in load over design, design quality, and type of materials affecting all of these factors, if not addressed, will lead to a reduction in the useful life of the structure. Therefore, handling bridges and timely maintenance of them will increase the useful life of the bridges. In this research, the evaluation bridges of Mazandaran province has been considered for the needs of maintenance. In order to carry out this research, firstly, the field visits of high importance bridges in Mazandaran province (more than 100 bridges have been investigated and evaluated in this research), and the failure and defect status of each of these bridges As well as the condition of these bridges against the factors such as traffic load and river bed, were studied. After conducting field visits and collecting the required results, we have studied the priority of each of the bridges in Mazandaran province regarding the need for maintenance. Also, in order to determine the amount of costs necessary for the maintenance of bridges, experts in this field were used and each bridge was evaluated separately and finally the amount of repair cost needed for each bridge was identified.

In this paper, attempts are made to compare the seismic fragility and the probability of failure of steel structures supported on different types of friction pendulum isolators. These isolators including single friction, dual friction pendulum and triple friction pendulum are designed to have similar effective periods as a prominent characteristic of them. The designed bearings have 3- to 5-second effective period and supports 3- and 6-story moment framed steel structures. These two superstructures represent short-range and intermediate-order buildings based on HAZUS technical manual. Three-dimensional nonlinear models of the structures are idealized in a finite element framework and nonlinear time history analyses are performed. In order to compute the fragility of the structure, the probable uncertainty sources in an isolated building such as earthquake record, modeling, design, and properties of materials in a probabilistic framework are considered. Furthermore, incremental dynamic analysis (IDA) is performed and the fragility curves of the structure are obtained in slight, moderate, extensive and collapse damage states (DS). Calculating the failure probability according to FEMA P-695, it is showed that all the isolated structures have less than 10% collapse probability. In addition, it is revealed that the triple concave friction pendulum (TCFP) has greater collapse margin ratio (CMR) than other kind of friction bearings. Growing the effective period of TCFP from 3 to 5 seconds, increases the CMR nearly 70 percent.

With the increasing global population in recent decades and the increasing number of construction projects in the world, researchers and scientists from various sciences are thinking about restoration of civil engineering structures, which has reached to useful life of many of these structures. The failure of part of these structures leads to the destruction of the entire structure, which results in the wasting of large amounts of capital from owners and owners of these structures. Destruction and rebuilding of such structures are not at all cost-effective. Therefore, the science of health monitoring of structures in order to solve these problems has attracted researchers in recent years. So far, various methods, including X-rays and ... have been used to find the damaged member, but these methods can only be used on members of the structure that is available. And they are not comprehensive for the whole structure. For this purpose, vibration-based methods were introduced. Among the vibration-based methods, modal field methods have been of major interest to the researchers for their simplicity in performance. One of these methods is the mode shape curvature method, whose intrinsic ability to detect and locate damage is obvious to everyone. In this study, taking into account the noise generated by the mode shape data acquisition, more careful attention is needed in the field of damage detection. For this reason, the damage index was used as an indicator of the damage. The results indicate high accuracy of the method in identifying low-intensity damage and high noise level in higher modes.

Sediment in the dam’s reservoir has a significant role on mitigation of dynamic response of concrete gravity dams and also the seismic response of dams in near-field motion can be considerably different from those observed in the far field and the near-fault ground motions can cause considerable damage during an earthquake. This paper presents results of a study aimed at evaluating the sediment effects in the near-fault and far-fault ground motions on nonlinear dynamic response and seismic damage of concrete gravity dams including dam-reservoir-foundation interaction. For this purpose, 3 as-recorded earthquake records which display ground motions with an apparent velocity pulse are selected to represent the near-fault ground motion characteristics. The Shafaroud gravity dam, which is selected as a numerical application, is subjected to a set of as-recorded near-fault and far-fault strong ground motion records and three different level of sediment are assumed. Results show that in the near-fault horizontal earthquake with assuming 2 m sediment height a 3.67% reduction and with 8 m sediment height a 10.33% reduction in dam crest displacement are obtained but in far-fault ground motion reservoir sediment do not have a sable pattern effect on dam’s response. Therefore, any dam must be evaluated for sediment effects on its dynamic response individually.

In Chevron braced frame, due to the buckling of brace on one story, an unbalanced force arrives perpendicularly in the middle of the beam, causing the destroy of the floor and, at the end, causes structural failure. On the lower floor, due to the buckling of the compression member, an unbalanced vertical force has arrived at the location of the upper beam of the braces, which results in a large displacement in the middle of beam. The result is a very strong and uneven beam with other members of the structure. To deal with this situation, Zipper column members are used. In the zipper braced frame, when the zipper mechanism is formed in the frame, the lateral load capacity of the frame is reduced and unstable, which can be remedied by applying a suspended braced zipper frame. In this study, for the comparison of the Chevron braced frame and Zipper braced frame from the 4, 7, 10, 15 and 20 stories of the structures under 7 records in the OpenSees software, a analysis dynamic of time history was performed and the maximum parameter required the drift angle of story and the maximum requirement rotation of story for comparison was selected. At the end, it is concluded that the average records in the index of drift angle in the 4 and 7 story frame are about 30%, in the 10-story frame of about 10%, and in the frame 15 and 20 stories less than 5% of the zipper brace frame is lower than the chevron braced frame on the roof. Also, it is deduced from the angles of rotation, Zipper bracing frame Average records on the roof is 30% in the 4-story frame, , less than 5% in the 15-frame frame and less than 3% In the 20-story frame dropped.

The columns are one of the most important members of the construction structures, which is responsible for the bearing and transfer of loads to the structure. The behavior of compressive RC members is generally based on the concrete strength and ductility of concrete which with confining concrete can improve both of them. Researchers have also been keen to integrate the reinforcement of the concrete columns in order to simplify construction and save on structural and economic costs. Based on these mentioned cases, in the present study, a new type of configuration is presented using rectangular spiral reinforcements with continuous hoops for rectangular concrete columns, which is examined by numerical model. For the modelling and analysis of the new columns, the finite element method has been used with the Abaqus software by using of a verification experimental sample. The parameters studied are various arrangement of using rectangular spiral reinforcement, number and pitch of spirals. Bearing Capacity and Ductility Capacity of the New Models were compared with previous designs using circular spiral reinforcements. According to the results, the use of such a configuration, in addition to simplifying the structural and construction, has increased the bearing capacity and the ductility of the columns.

Precise investigation of the connections in a steel structure is important, and inaccuracy in the design and implementation of connections not only does cause failure in the connection, but also has a devastating effect on other members of the structure. Bolted end plate connections are commonly used in steel structures. There are two types of beam-to-column flange connections, four-bolt and eight-bolt. The four- bolt connection is used for low anchor values and the eight-bolt connection is used for large bending anchor values. In this study, the cyclic behavior of the restrained beam-to-column connections with end plate under cyclic loading has been evaluated. In the calculations, all of the parameters affecting the behavior of this connection have been investigated and solutions are proposed to reach the maximum connection capacity. Since the behavior of this connection depends on several factors, two general models of beam connection to different columns with beams of 30 and 40 cm depth are considered for research purposes. The thickness of end plate, shape of end plate, thickness of the column flange, strength or material of the bolts, the necessity of using continuity plate, stiffener and doubler plate are among the parameters considered in the analyzes. According to the results of this study, the use of a thin-walled end plate leads to local buckling of plate. The use of continuity plate is very important and prevents local buckling in the panel zone. Also, in cases where the thickness of the column web is low, the use of a doubler plate will also be necessary. In addition, the use of a stiffener improves the flexural strength of the section.

In last decades with an increase in the number of terrorist attacks and other unintentional explosions, the study of blast loading and response of infrastructures have gained much importance. Elevated liquid storage tanks are one of the major infrastructures that play important role in industries. Liquid storage structures can use for the storage of water, milk, liquid petroleum and chemicals in industries. Blast loading on liquid storage structures may lead to disaster due to water crisis. Hence, understanding the dynamic behavior of liquid storage structures under blast loading through numerical simulations is of utmost importance. In the present study, three dimensional (3D) finite element (FE) simulations of a steel water storage elevated tank with annular baffle that put in the specific height of tank’ s wall subjected to blast loading is investigated using the FE software ABAQUS. The coupled Euler–Lagrange (CEL) formulation in ABAQUS has been adopted herein which has the advantage of considering the coupling of structural mechanics and fluid mechanics fundamental equations. Three different aspect ratio (H/R) are considered in the present study and two different water levels, i.e., full tank and half full tank are considered. Obtained results show that baffle reduces overturning moments and sloshing in both cases of full and half full tanks.

Concrete density is always a problem that occurs during concrete and it affects the strength, durability and apparent qualities of hardened concrete. Vibration is a practical thing that comes with a lot of noise and requires trained workers, and failure to do so will cause many problems. To overcome this problem, the development of self-compacting concrete has begun. This concrete, fills all the dimensions of the mould and is flowing through the use of more fine-grained and plastic shrinkage, without the need for vibration, without any parts being detached. The topics that have been considered for many years in concrete technology have been resilient and durable. For concrete having self-compacting and high resistance and durability, high- performance self-compacting concrete (HPSCC) has been created. The achievement of self-condensation requires the use of a large amount of powdered material, some of which are capable of replacing part of the cement, and replacing them is a step towards sustainable development. Also, using powder materials, the density of concrete aggregates increases and leads to improved strength and durability. The use of large quantities of powdered materials increases the need for mixing water and the likelihood of plastic shrinkage. Therefore, it is necessary to consider all items to enhance concrete performance, so that HPC can be designed and constructed. Therefore, in this research, a review of previous studies on the nature, mechanical properties and durability of highly capable HPSCC’s has been carried out and about 90 high citation articles have been considered, focusing on goals and results. The results of previous studies have shown that using SCC, concrete with similar strength of conventional concrete can be obtained. By reducing the proportion of water to cementicious materials, as well as using pozzolans, not only resistance but also concrete properties are enhanced and HPSCC is obtained.

Human resource development is an essential part of human resource management in construction projects. Generally, planning in this area consist of employment, skills improvement and development of workforces. Meanwhile, human resource development is based on training and motivation. In this paper, the role of training and motivation in human resource management of construction projects is investigated. Next, the Causal Loop Diagram (CLD) of human resource development along with complex relationships between factors is obtained using system dynamics approach. Thereafter, the Stock-Flow Diagram (SFD) of human resources development of construction projects has been developed. The information needed to quantify the simulated model has been gathered for a mass housing project. The archived simulation results demonstrate that implementation of financial incentives results in 12% productivity improvement. Besides, delays in labor payment decreased 18% of productivity. The productivity has been also improved about 20% by applying training policy. The presented model has the potential to evaluate the training and motivation of human resources as two main strategies of human resource development, taking into account the dynamics of the project. Finally, the effect of applying human resources development policies on project performance in terms of time can be evaluated using this model. It is also possible to plan the human resource development of the project and to improve the labor productivity and project performance.