Year:2023 | Volume:53 | Issue:2|Papers Count:18

Tensegrity systems have been used as a class of light space structures in the various forms including flat modular systems, barrel vaults and cable domes. Conventional cable domes achieve their stability through a concrete compression ring, which is inconsistent with the self-support characteristic of tensegrity systems. The previous evidences also showed that the presence of a rigid support system such as a concrete ring around the space structure especially subjected to seismic loads may cause more structural damages in boundary region of structure. In this research, the combination of a Levy-type cable dome with a tensegrity ring created by the semi-regular modules is considered, which leads to a new hybrid cable-strut system. Form-finding of the studied structures is carried out using the force density method. After designing the hybrid structure, its initial collapse behavior is evaluated by the numerical finite elements method. In this regard, static and dynamic analyses are performed on both the hybrid structure and the cable dome attached to rigid supports to evaluate the effect of the tensegrity ring on the cable dome behavior and also the adequacy of static analyses to estimate capacity of the structures. After estimating the initial behavior and the collapse mechanism type of the studied structures, their behavior, are improved by equipping a number of critical struts with Force-limiting devices.

The Earth’s climate has been changing since began drastically. Global warming and change in precipitation pattern are consequence of climate change. Climate change and over-withdrawal of water for industrial purposes has increase water stresses around the world. Long-term water stresses may cause disasters. Hence it is necessary to control water stress. This paper proposes a model to manage water stress of different catchments by proper locating of large industries considering climate change.

In recent years soil reinforcement and improvement techniques have gained widespread applications in different aspects of geotechnical engineering. It is apparent that reinforcing/stabilizing a weak/problematic soil is more economical than replacing it with select fills. A contemporary method of soil reinforcement/ improvement is the application of fibers-natural or synthetic (polymeric) with random distribution within the soil (Hejazi et al. 2012). More recently, there has been a trend in utilization of recycled fibers for soil reinforcement/improvement purposes (Valipour et al. 2021). This treatment dwells on the application of Recycled Tire Polymer Fibers (RTPFs) for enhancing the shear strength of Babolsar sand.

In the 1970, Popov et al. Developed plans to make plastic joints in frames with eccentric bracing to increase energy dissipation (Roeder and Egor, 1978), and since the late 1980s, the use of steel dampers has been common in countries such as Japan and Indonesia. Has been. Different types of steel dampers have been used since then, for example ADAS, X-shaped and honeycomb dampers are some of the steel dampers that are still under development and research studies have been done on them (Askariani et al. 2020).

Generally, the modeling of the Water Distribution Networks (WDNs) is done by the conventional methods that cause the outputs of the network are normally deterministic value by assuming certain inputs and parameters. But, in real ones, there are many uncertainties in model parameters. which causes, the results obtained by the conventional methods may not be satisfactory in practice, Therefore, the variation of key parameters in WDNs such as pipe roughness and diameter and also nodal demand can change nodal pressure and pipe flow that affected the performance of the network. However, by understanding the parameter uncertainties and how the uncertainties affect the accuracy of the model, the decision-makers can make the best decision that can prevent the WDNs from the unreliable events.

Current research has tried to study the effects of curing ages, curing temperature and Recycled Tire Polymer Fibers (RTPF) content on geotechnical properties of RLCC, such as unconfined compressive strength (UCS), secant modulus (Es), strain frailure ( and deformability index (. The UCS test is a criterion to estimate the geotechnical parameters of RLCC samples in the presented research.

The importance of seismic vulnerability of historic buildings in Tabriz and the high seismic risk in this region, such as the recent Turkmenchay earthquake in 2019 (5.5 magnitude earthquake), justifies the study of seismic vulnerability of historical buildings based on a principled method specific to historical buildings. Since there is no guideline in Iran to assess the seismic vulnerability of historic buildings, therefore, the present study has aimed to evaluate the seismic vulnerability assessment of the Kalantar historic house in Ultimate Limit State (SLU) and Damage Limit State (SLD) based on the Level1 and Level3 of Italian guidelines for historical monuments (DPCM, 2005), by emphasizing on the reliability and the limits of the simplified mechanical model (Level 1). The first level of evaluation (LV1), is oriented to highlight, on a regional scale, critical situations in terms of seismic vulnerability and to provide a classification of risk and a priority list for further investigations aimed at the conservation of the architectural heritage. Adopting a force-based approach, this level relies on a simplified structural model that requires integrating a limited number of geometrical and mechanical parameters with qualitative data derived from visual tests, construction features, and stratigraphic surveys. The LV3 is based on the global structural response of the building in order to define the values of acceleration leading the structure to each limit-state. In this case, the displacement-based approach is adopted, for which the global behavior is governed by the in-plane capacity of the walls discretized in panels where the nonlinear response is concentrated. The seismic safety is evaluated for each level by an index summarizing the comparison between the expected seismic demand and the seismic capacity. It is worth noting that LV1 and LV3 are based on simple and accurate global models, respectively, which are both represented by the combined effect of floor diaphragms and the in-plane response of structural walls, so, it may be concluded that they are directly comparable.

The present paper investigates the effect of soil-structure interaction on the seismic behavior of base-isolated frames under near and far-fault earthquakes. For this purpose, the nonlinear time history results of 1, 4 and 8-story base-isolated frames are compared with corresponding fixed base ones. ABAQUS finite element software is used for numerical modeling on which time history analyzes are performed.

During a flood, water flows out of the main channel and enters the floodplains. In nature, due to the influence of local topographic conditions, rivers have often irregular and non-prismatic shape. In non-prismatic compound channels, because of the effect of changing in cross-sectional area along the channel, the flow structure is more complex than prismatic compound channels. Therefore, it is important to study the flow characteristics in such channels and it can help researcher to better understand the flow behavior in rivers, especially during floods. In the present study, the flow characteristics in a compound channel with inclined and skew floodplains has been investigated experimentally. The experiments were performed at three relative depths of 0.2, 0.3 and 0.4 and for two skew angles of 11.31° and 3.81°. The water surface profile, lateral distributions of velocity and boundary shear stress along the skew part of the flume have been measured and reported. The results of experiments indicate that the lateral distributions of velocity and boundary shear stress in skewed compound channels with inclined floodplains are non-uniform and asymmetric. Also, the flow velocity and boundary shear stress in diverging floodplain are always higher than its value in converging floodplain. By increasing the skew angle of the floodplains from 3.81 to 11.31 degrees, the boundary shear stress and flow velocity in the main channel and on the floodplains increase.

Generally, using predictive methods for finding critical points and repairing the damage pipes based on these approaches is less costly than renewal them after occurring failure. In this study, by calculating direct costs, two scenarios of “on time repair” (first scenario) and “repair after failure” (second scenario) are proposed to repair the wastewater network pipe. As a case study, part of Isfahan wastewater network (region 2) and its failure data during 1393 to 1396 are considered and the obtained results are presented and compared.

1. Introduction In the present paper, results of a study on the use of Bacillus pasteurii to reduce wind and water erosion in alkaline silty soils are presented (Kim et al., 2014). The treated soil specimens were prepared in different periods and different concentrations and amounts of bacteria on different surfaces and were exposed to a wind tunnel constructed and calibrated for the present study and their surface erosion was measured. For further analysis of the samples, melting and freezing tests, cone penetration, electrical conductivity, pH and SEM, XRD, and EDS analyzes were also performed on the treated and untreated specimens. The results of this study showed that the use of MICP as a surface crust is an effective and environmentally friendly process to control dust caused by wind erosion in the Meighan Wetland. 2. Methodology 2. 1. Experimental study The treated soil specimens were prepared in different periods and different concentrations and amounts of bacteria on different surfaces and were exposed to a wind tunnel constructed and calibrated for the present study and their surface erosion was measured. For further analysis of the samples, water erosion test (Gao et al., 2020), freeze and thawing test (Qi et al., 2006), cone penetration, electrical conductivity, pH and SEM, XRD, and EDS analyzes were also performed on the treated and untreated specimens. To compare the stabilization method with bacteria and conventional stabilizers, surface stabilized samples were prepared by spray method (Ivanov & Stabnikov, 2016) of cement and lime and exposed to wind tunnels and surface erosion was measured. 3. Results and discussion 3. 1. Effect of bacteria on reducing wind erosion The results of this study showed that the use of MICP as a surface crust is an effective and environmentally friendly process to control dust caused by wind erosion in the Meighan Wetland. With this method, the surface resistance of 28-day-old samples can be increased up to 95% and the rate of wind erosion can be reduced to 89. 8%. 3. 2. Effect of bacteria on water erosion The formation of biological crust in a scouring cycle by 98. 59% has reduced the surface scouring, which can indicate the stability of this crust against water erosion in the study area. 3. 3. Effect of bacteria on freeze and thawing cycles Freeze and thawing cycles do not cause surface crust loss and increase wind erosion in bacterial-modified soil samples. 4. Conclusions The use of bacteria to improve the soil and create a biological crust by spraying has shown a significant effect on the rate of erosion of samples exposed to wind and this method can be used in fine-grained soils of Meighan area and soils with similar conditions to prevent surface erosion. This method increases the surface resistance of the soil against melting and freezing, scouring, and penetration of the cone. Soil bacterial stabilization in the study area is more suitable than cement and lime stabilizers in terms of reducing erosion and reducing pollution.

Numerous parameters affect the solid waste production rate, including weather-climate parameters and parameters related to people's economical-social and cultural conditions, format, and detail of the city population, lifestyle, etc. In studying the effects of the mentioned criteria on the waste production rate, classic methods cannot analyze the time-based changes in parameters and the dynamic changes in solid waste production rate. On the other hand, the lack of precise data, an overall plan on solid waste management increases the need for a dynamic method. Linear regression is not a decent method in this research because of the seldom linear relation between parameters. A method, including modern estimation methods and models, is needed to omit the mentioned errors. ANN and LSSVM are for modeling in this research. Considering the significant part of seasonal patterns, using a preprocessing method that can extract such patterns can improve modeling; therefore, using the WT-ANN method can help.

Calculating the ultimate bearing capacity of a foundation by limit analysis allows determining the exact upper bound of bearing capacity of the foundation. In the present study, the cohesion coefficient (Nc) of a strip foundation on a single layer of soil overlaying bedrock was calculated. For this purpose, the upper bound of limit analysis combined with finite element method (FEM) was used. The soil behavior was assumed to be plastic and the Mohr-Coulomb failure criterion was used which allows description of soil mass by two parameters of cohesion and internal friction angle. It was assumed that the soil cohesion is not constant with depth and rather increases linearly. Finally, the bearing capacity was obtained using an optimized procedure (i.e., linear programming). In this regard, the Mohr-Coulomb criterion should be linearized in a stress condition. The cohesion depends on different parameters such as friction angle (φ), the ratio of soil depth to foundation width (b/h), and the cohesion variation with depth (ρ). To validate the results, obtained constant cohesion values were compared with those obtained by other researchers. The effect of the parameters on N_c was separately plotted and the calculated design charts were discussed.

Recently, industrial development and high growth of constructions have increased the need to pay attention to the improvement of construction sites. Meanwhile, soil biological improvement as a new, low cost and environmentally friendly method has been considered by many researchers. On the other hand, the use of micro piles by cement or chemical grout injection as one of the methods of soil improvement has been proposed since almost the middle of the twentieth century. Of course, one of the disadvantages of micro piles is the use of cement or chemical grouts, which have both limited resources and environmental pollution. The use of biological micro piles is one of the new and economical solutions to solve these problems.

Plastic hinge properties play a crucial role in predicting the nonlinear response of structural elements. The plastic hinge region of reinforced concrete normal beams has been previously studied experimentally and analytically. The main objective of this research is to evaluate the behavior of the plastic hinge region of reinforced concrete deep beams and its comparison with normal beams through finite element simulation. To do so, ten beams contain six deep beams, and four normal beams, under concentrated and uniformly distributed loading, are investigated. Lengths in the plastic hinge region involving curvature localization, rebar yielding, and concrete crushing zones are studied. The results indicate that the curvature localization zone is not suitable for the prediction of plastic hinge length in reinforced concrete deep beams. Based on the results it can be stated that in simply supported normal beams the concrete crushing zone is focused on the middle span, but in simply supported deep beams by creating a compression strut between loading place and support, the concrete crushing zone spreads along the compression trajectory. The rebar yielding zone of simply supported beams increases as the loading type is changed from the concentrated load at the middle to the uniformly distributed load.

Considering its key effect on the welfare and health of society, water plays a crucial role in the growth of communities and is one of the most important natural resources. In recent years, the problem of scarcity of water resources has been exacerbated by the growing population worldwide and increased competition for access to water resources, which leads to increased costs of water use. Therefore, the use of this vital resource requires proper management. The present study was entitled Predicting and Modeling the Urban Water Consumption Pattern in Tabriz to Investigate and Analyze the Urban Water Consumption Pattern Using Geographic Information System (GIS).

Tubular structures are made of hollow steel members with circular cross-sections and connecting them is one of the major challenges in their design. So far, some techniques to improve the performance of tubular connections have been proposed. Most of these methods can only be used for structures during the fabrication, but there are only a few techniques that can be applied during both fabrication and operation. Due to the successful experience of using composite materials for the repair and retrofitting of structures, special attention has now been paid to examining the efficacy of these materials in offshore structures.In this research, the effect of CFRP and GFRP wraps on the ultimate strength and deformation of tubular X-joints under compressive load is investigated. For this purpose, the results of the finite element (FE) models were validated with several available experimental tests. After that, the nonlinear static behavior of tubular X-joints strengthened with FRP was studied. In these FE models, the contact between the FRP layers and the steel members (chord, weld, and braces) was considered. Also, the weld profile in the brace/chord intersection was modeled.

The research on tall buildings has been increased due to the demands of suitable spaces. The use of pyramidal architecture in tall structures has several benefits including the ability to lighten the adjacent buildings and prevention from the closure of the view in urban spaces. However, the seismic behavior of pyramidal tube structures requires a closer examination of their design and probable behavior under lateral loads. One of the most important parameters in the pyramidal tapered buildings is the calculation of natural frequency of the vibrating structures (ω). In this study we have proposed new equations and methods for the mentioned calculations which has been compared with software calculations. Many researchers have calculated the free vibration of structures using different methods. One formula to obtain the natural frequency of tube structures is obtained from the fourth-order differential equation (Wang, 1996). An approximate solution in order to analyze the free vibration of tall tube-in-tube buildings have been proposed by different researchers (Lee, 2007; Lee and Bang, 2008; Lee and Tovar, 2014). The modeling of tall building using a beam with varying stiffness and mass subject to the variable axial force caused by simple weight was presented by Mohammadnejad (2015). Free vibration analysis using differential equation has been evaluated by Bozdogan (2009) and Bozdogan (2013). The first natural frequency of tall buildings with a system combined of framed tube, shear core, and belt truss has been calculated under axial force (Kamgar and Rahgozar, 2014; 2015; 2018). A new and simple method of determining the natural frequency of tube structures with tube-in-tube wall has been presented. The novelty of this method refers to the mathematical computation process which is much simpler and shorter. The effect of structure’s weight on the natural frequency of structure has been considered by variable axial force. Tall building is modeled by a beam with variable stiffness and mass along the height of the building. Therefore, the partial differential equation with variable coefficients is used which have been presented by Mohammadnejad and Haji-Kazemi (2018). Furthermore, there is no regular research on the vibrational frequency calculation of pyramidal tube systems, especially by mathematical methods, or a small number of studies have been done most of which have been done on 90-degree structures with tube systems.