نشریه مهندسی سازه و ساخت
سال دهم شماره 10 (پیاپی 75، دی 1402)

Bridges are key elements in the highway transportation system. Many bridges collapsed or were extensively damaged in past earthquakes, which highlighted the vulnerabilities of existing bridges. Therefore, different rehabilitation methods have been developed for mitigating earthquake hazards in new bridges or retrofitting existing ones. Isolation systems are one of the most commonly used devices that have been developed to dissipate earthquake energy and improve the seismic behavior of bridges. Friction pendulum System (FPS) is a sliding-based isolator, widely used in the seismic design of bridges. Recent investigations show that bridges with FPS isolators exhibit good performance against seismic forces due to the energy dissipation of the isolation device. The purpose of this study is to assess the effects of the vertical component of the earthquake on variations of axial forces of piers in a three-span continuous deck reinforced concrete(RC) bridge, seismically isolated by the FPS. To this end, incremental dynamic analyses (IDA) are conducted using a suite of 24 near-fault ground motions to evaluate the dynamic behavior of the bridge piers. IDA curves and Fragility curves are generated with peak Ground acceleration and column drift as intensity measure and Engineering Demand Parameter (EDP), respectively. The results showed that the vertical component of earthquake can increase the axial forces of piers significantly. Moreover, the damage probability of the moderate and extensive damage states showed 6% and 24% increase, respectively, And The damage probability of Isolators increased by 21% considering the vertical component of the earthquake.

AbstractIn the present study, the evaluation of the seismic performance of steel framed buildings on two types of seismic isolation systems under far-fault earthquakes has been investigated. The isolator used are lead rubber bearing and single arc friction pendulum system. In order to compare the behavior of these isolators, the effective time period is considered as one of the most important properties of the isolator. The effective time period of the isolators is 2.5, 3.5 and 4.5. Three types of steel framed buildings with special moment resistant steel frames of 3, 7 and 12 stories are placed on these isolators. These three buildings represent low-rise, mid-rise and high-rise buildings. The effect of these two types of seismic isolators has been investigated in reducing the acceleration response and the relative displacement(drift) of the floors. The results show that the efficiency of both types of lead rubber bearing and single arc friction pendulum system decreases with the increase in the height of the building. The efficiency of the single arc friction pendulum system is 14% lower than that of the lead rubber bearing. Increasing the target natural period (decreasing the stiffness of the isolator) in reducing the response of the buildings in the lead rubber bearing has an average of 27% better performance than the single arc friction pendulum system.

Building information modeling is a digital representation of a building or infrastructure that helps architects, engineers, and construction professionals design, plan, and manage construction projects more efficiently. There is a need to integrate building information modeling techniques in construction projects to increase the efficiency of the project, in the meantime, different technologies can be used to improve the efficiency, therefore, in this research, the scanning technique for modeling is investigated. The building information is in the projects under construction. In the meantime, the qualitative part of the research, which includes studies and extraction of effective factors from previous related research, has been started, which has been completed by confirming and screening the factors using the fuzzy Delphi method and focusing on the opinion of experts in two phases. In order to calculate the adequacy of the size of the statistical population, the sphericity-Bartlett test was used and the results obtained were confirmed by experts. Based on the standard coefficients, the index of data processing collected with a coefficient of 0.94, the index of data collection with a coefficient of 0.86, the index of choosing the optimal laser scan with a coefficient of 0.79, the index of using data in modeling with a coefficient of 0.68, Results checking index with a coefficient of 0.64 and quality inspection index with a coefficient of 0.59 can be prioritized. By using factors such as preparation of a preliminary map in order to manage encounters in the process of data collection and display them in the form of geographic information system maps, and to monitor the dimensions and components of the project It is provided to design and implement the building with higher efficiency.

The use of 3D printing concrete in construction applications is one of the most innovative and challenging fields, combining traditional construction knowledge with digital technologies. The focus on this area has increased due to removing the molds, reducing the cost, needed human resources, and other important advantages. There are many challenges such as rheological requirements, bonding between layers, materials used, their reinforcement, and anisotropic behaviors in this industry which has a special potential in fast and mass construction, and complex architectures. Throughout history up to current times, the performance of the built structures has always been the result of the interaction between steel and concrete. According to the practical applications of this technology, manufacturing compatible materials, using reinforcing systems such as fibers and steel rebars, and maintaining proper interaction between them, are fascinating subjects that attract the attention of researchers in this field. The examples of the research processes along with their analysis are reviewed in this article. since this article was written to introduce this technology and its challenges, it provides a source of inspiration, for getting to know the audience as much as possible, with conflict goals of producing suitable concrete to improve the ability of printing and its quality.

The concrete surface is the most significant part as it is in direct contact with the outside world. Therefore, increasing the surface strength of concrete could reduce the absorption of harmful substances into the concrete. Permeability and surface strength can be regarded as factors that affect the durability and service life of a concrete structure. As a result, a concrete structure with the desired surface strength and low permeability is of paramount importance. Hence, this study attempted to measure the surface strength and permeability of concrete through “twist-off” and “Cylindrical Chamber” tests under temperature cycling. Relations between the surface strength and permeability of concrete samples were obtained. In addition, a linear function was used to estimate the relation between penetration depth and volume with high precision. According to the twist-off test results, extending the curing age of plain concrete would increase the surface strength; the surface strength at the age of 120 days exceeds that of 7 days by approximately 42%. However, when temperature cycling was performed on the samples, the surface strength of the concrete caused by the twist-off Test decreased. Further, results from the permeability tests using a cylindrical chamber indicate that temperature changes have a negative influence on the permeability and penetration depth in concrete samples. The permeability and penetration depth of concrete under temperature cycling caused an 8-fold and 3-fold increase after 120 days, respectively. According to the results of the study, moderate temperature cycles significantly affect permeability and penetration depth.

Using sea wave as an energy resource is growing in the world because of its cleanliness and recyclability. Wave energy depends on significant wave height and wave period. These parameters depend on the specification of some other parameters specially the wind filed. Blowing the wind over the sea water produces waves and makes them one of the best sources of energies. Hence wave climate depends to wind climate. Variation of the wind climate in the future climate, changes the hydrodynamic of waves including the wave power specification. The CNRM-CM6-SSP2-45 of CMIP6 is one of the middle classes carbon dioxide climate changes and has much application in managing and programing purposes. In this research the effect of this high-resolution climate scenario has been evaluated on the wave power in Chabahar in Sistan and Balouchestan province in the Gulf of Oman. For this, the improved Weibull downscaling technique has been used for downscaling of wind field. Using a calibrated wave model, it has been derived that in a period of ten years leading to 2100, the wave power will increase 0.22 kW/m (equal to 3%) in average. Seasonal variation is more sensible. Fall and Winter have most increasement in decrease. Average seasonal wave power will change in Fall and Winter by +2.27 kW/m (+42%) and -2.24 kW/m (-27%) respectively.

nowadays, one of the biggest challenges in the construction industry is the occurrence of multiple claims in projects, which are a factor in creating disputes in the project. Therefore, managing these claims is a factor in reducing these disputes and thus a success for the legal-contractual part of the project. On the other hand, the design and build implementation system has helped to reduce construction claims due to the reduction of the main elements involved in the project; But it is always inevitable that a claim will occur in the project. Therefore, considering the success of employers in the construction industry to this type of system and its acceptance by contractors, and the importance of claims management in this type of projects, recognizing the contractual claims of employers and how to deal with it is one of the important issues that should be considered in the legal-contractual sector of Projects, employers and especially contractors.Therefore, in this study, using previous research and with the help of expert opinions and study of 10 case studies, first, the contract claims of employers in non-industrial design contracts (EPC - Package 84) were examined and then 51 causes and 3 general origin of reasons were identified. Then, by examining the settlement methods provided in these contracts (employer request) and classifying them into 11 groups, the general algorithm of occurrence of contractual claims of employers was drawn and 51 reasons for claims were classified according to this algorithm. According to the obtained results, the employer's contractual demands from the claim are classified into 4 general categories: time, cost, and doing a specific (practical) work and termination.

In this study, the bond strength between rebar and high-performance fiber-reinforced cementitious composites (HPFRCC) containing the combination of three types of steel fibers (1% and 2%), polypropylene and polyvinyl alcohol (0.1, 0.2, 0.3 and 0.4%) has been investigated at the temperature of the laboratory, 400 and 600 °C. For this purpose, at first, 19 specimens were constructed and evaluated for compressive strength testing under the mentioned temperatures, as the silica fume was considered 20% by weight of cement. Among the constructed HPFRCC, four superior mix designs were selected for investigating the bond strength between rebar and HPFRCC using pullout test. The results showed that the bond strength between rebar and HPFRCC samples containing 2% steel fibers with PP fiber in such a way that increasing the temperature up to 400 °C, decreased about 38%. while this reduction rate for the samples containing PVA fibers is about 26%, and this means that PVA fibers have a better performance than PP fibers in term of the bond between concrete and rebar when exposed to high temperatures. By increasing the temperature up to 600°c, the bond strength of rebar and HPFRCC continues to decrease until this drop is about 64% for selected samples containing fibers (2% steel and 3% PP) at the laboratory temperature (i.e., 23°c). The reduction for the HPFRCC sample containing 2% steel and 2% PVA fibers is calculated by 62%. The results of this study and the literatures indicated the effect of different parameters on the bond strength, so for further investigation, the bond strength modelled using artificial intelligence models. The results of rebar bond strength modeling in HPFRCC showed that the performance of the adaptive multivariate regression splines based on error statistical criteria was more accurate than the artificial neural network.

The purpose of this research is to simulate close to reality how water moves in the soil in geotechnical engineering issues, which has a special importance and position. Over the years, several numerical methods have been proposed to solve the general equation of water flow in the soil, but in this study has been tried to use the Richard equation and the Crank-Nicholson separation technique and the finite volume numerical method to move water in Soil to be analyzed. For this purpose, two widely used and important issues have been examined. In the first problem, estimating how water moves behind the excavation wall in areas where the groundwater level is high, and in the second problem, how water moves between two subsurface drains at the same depth when the water level rises due to rainfall.

Availability means the stability of the network in operational conditions and at a given time. In other words, the network should not be turned off during operation, and if it is turned off, the failure must be fixed at a certain time. Availability is a combination of system reliability and maintainability. Broadband optical telecommunication networks are used to transfer high capacity domestic or international data in the form of data transmission. In the international traffic transfer agreements, there are network quality level agreements that, if the access level is lower than the agreed levels, or blackout. network, network owners suffer heavy losses. Also, in various industries such as the railway industry, train control structures are based on optical telecommunication networks, and reducing the level of network access may lead to blocked railway lines and irreparable accidents, so high availability leads to stability. network and reduce line congestion. In this article, in addition to modeling the increase in the access level of the optical transmission network (the implemented case example of the optical transmission network of the Hormozgan railway region) and observing its results in reducing the blockage of railway lines, the behavior of the network through the Monte Carlo method of prediction and simulation has been made

Special Truss Moment Frame (STMF) is a type of steel moment frames that has high lateral stiffness due to deep girders and can be used over long spans. For an STMF subjected to cyclic loading, energy dissipation is provided through the yielding of the special part located in the mid-span. This paper presents a numerical study on the cyclic behavior of STMFs in which the special part is equipped with yielding damper as a means of energy dissipative device. For this purpose, it is aimed to investigate the effect of the parameters of X-shaped pipe damper (XPD) on the cyclic behavior of STMFs. The application of these dampers has been investigated in two configurations; once with clamped and again with pin-ended beams at the special part. The results of finite element analysis are compared based on the parameters of cyclic behavior (stiffness and strength), the amount of maximum cumulative plastic strain and the energy dissipation capacity of the specimens. Based on the results obtained from the analysis of the STMF with pin-ended beams at the special part, the use of proposed X-shaped damper increases the energy dissipation capacity of the frame by 70%. Increasing the thickness of the X-shaped pipe damper increases the yield and ultimate load bearing capacity of the frame. In addition, the stress and strain concentration in the frame members is reduced which in turn prevents the damage evolution in these members.

The design codes prescribe the durability criteria by providing criteria such as the minimum thickness of the concrete clear cover, and the minimum permissible compressive strength. In the initial phase, these rules delay the effect of destructive factors, but with the initiation of rebar corrosion, these prescribed rules can have different effects on the propagation of destructive factors. One of the consequences of the rebar's corrosion is the creation of cracks in the concrete cover. Whit increasing the width of the cracks during the propagation of corrosion, the effects of external aggressive factors increase. In this research, using the most important existing experimental models for predicting crack width, the effect of prescriptive criteria on crack width has been investigated. For this purpose, the prescriptive rules of the concrete design code were considered as the initial condition of the structure according to the environmental condition of the reinforced concrete structure. The investigated models were selected based on chloride-induced corrosion. The important influencing parameters in the models were considered as random variables and the crack width was obtained as a random variable based on the existing models. The impact of rebar diameter selection in the environmental conditions defined in the design code on the crack width has been calculated. The calculation of the crack width was done using the Monte Carlo sampling method and the average of the experimental models and the coefficient of variation were calculated by considering the correlation between the models. The results have shown that the use of rebars with a smaller diameter reduces the crack width by 90%. Also, if the rebar corrosion begins and a certain period of time has passed since its beginning, the safety level of a certain structure is not the same due to the large difference in the width of the cracks.