s.mohammad mirhosseini

Clay soils with a water content of more than 35% or close to the liquid limit are known as soft clay. These soils have an unconfined compressive strength (UCS) of less than 25 kilopascals. In order to improve the strength of these soils, additives such as cement and nanoparticles are added to them. These additives are combined with soil, which is called cemented mixed soil. Therefore, this research investigated the effect of the simultaneous addition of Nano-silica with cement on changes in UCS of soft clays with low plasticity (cl). The research considers soil with a constant water content of 40%, exceeding its liquid limit, for all samples. The changes in three factors, the cement and Nano-silica content consumed and the curing time of the specimens, were investigated as effective factors. For cement, 8%, 10%, and 12% relative to the weight of dry soil were considered. Nano-silica at eight levels from zero to 1.4% relative to the weight of dry soil and three curing times 7, 14, and 28 days were considered. A total of 72 series of specimens were made, and the unconfined compressive strength was measured. The results indicate that using nano-silica up to 1.2% in combination with cement increases the UCS by an average of about 170% after seven days, 120% after 14 days, and 48% after 28 days compared to using cement alone. Additionally, adding nano-silica led to a reduction of up to 4% in cement usage. Equations were derived based on the consumption rates of cement and nano-silica, along with the curing period, to estimate the uniaxial strength of the samples. The average difference between the estimated and measured values for all samples ranged from 1% to 3%.

The Architecture, Engineering, Construction, and Operations (AECO) sector is adopting Building Information Modeling (BIM) in public and private organizations worldwide. The public sector plays an essential role in inducing and encouraging the implementation of BIM in the industry. However, there is a lack of comprehensive and integrated research on the critical factors for enterprise-scale BIM adoption in government agencies. The primary purpose of this study is to provide a framework to analyze the critical success factors (CSFs) of BIM implementation in Iranian government organizations. This method includes a comprehensive literature review, an exploratory study in three Iranian government institutions, and a survey conducted with 68 Iranian experts involved in admissions to public organizations. The methods used to analyze the factors are Interpretive Structural Modeling (ISM) and the DEMATEL method used to analyze the relationships and interactions between the factors quantitatively. The results include the proposal of sixteen CSFs and a model's development. Finally, the creation of a framework for adopting BIM by government agencies according to BIM contexts prioritized CSFs and levels of analysis. The main contribution of the current research is a proposed framework for BIM adoption, which includes a comprehensive and integrated approach based on a set of CSFs from Iranian government organizations and a greater understanding of contractual, regulatory, technical, procedural, and political characteristics for the public sector.

Research in building information modeling and sustainability studies has been increasing recently. However, few studies have been conducted to examine the integration of building information modeling technologies to strengthen the implementation of sustainability methods in the construction industry. Building information modeling technology is one of these methods because it creates vital databases for the building and its components instead of generating and displaying rich information IDs. As a result, executive management's time and costs are significantly reduced because of the ability to make optimal decisions regarding the implementation of projects at each stage. It has provided the construction. Building information modeling technology as a powerful manager tool improves project success criteria. This study aims to identify the dimensions and components affecting the sustainable development of the construction industry based on building information modeling. The method used in this research is Grounded Theory based on the study's exploratory nature. The primary basis of data collection is in-depth interviews with experts, professors, and construction project specialists of Tehran Municipality, District 3. A total of 15 interviews were conducted. After collecting the information, the codes related to the written interviews were analyzed. After performing three steps of open coding, axial coding, and selective coding, the final research model was presented. The codes obtained from the interviews were categorized into 55 concepts and 14 main categories. According to the results of this study, building information modeling and optimal building design are influenced by a range of environmental and causal factors. An integral part of the sustainable development of the construction industry is the integration of contractual models and sustainability development. The use of natural resources, the product, and the training of organizational and macro management and technology are included.

In previous earthquakes, many steel frames suffered damage to their ordinary rigid moment beam-to-column connections. As a result, the use of multi-level control systems in structures has gained attention from engineers in recent years. The main idea in this system is to combine two separate control systems with different stiffness and strength, thus creating dual seismic behaviors. In this study, a two-level friction-yielding damper passive control system is presented for beam-to-column connections, and its cyclic behavior is evaluated using nonlinear static analysis with the finite element method using ABAQUS software. The evaluation results demonstrate that the performance of the samples improves with an optimal ratio of length to thickness. This improvement is reflected in increased stability and area of the hysteresis curves, ultimately leading to higher energy absorption. Additionally, the hysteresis curves indicate a ductile behavior for the proposed damper in the moment connection. Moreover, the obtained hysteresis curves show that the system reliably dissipates energy at different earthquake levels, satisfying the seismic criteria for special moment resistant connections based on the AISC code. The proposed damper serves as an energy dissipating device, effectively dissipating energy at different levels of earthquakes by facilitating slip and yielding, thereby controlling the seismic response of the structure.

This paper investigated the effect of the stiffness of a light panel type with polystyrene core and lightweight concrete coating on the behavior of plain steel frames. An experimental study was performed on two large-scale specimens of one-story single-span. The behavior of panels and determine the effect of their stiffness, an in-plane infill-frame interaction frame, including a steel frame with isolated and non-isolated panels, were investigated. The specimens were tested under controlled displacement to investigate the in-plane infill-frame interaction of steel frames. Both isolated and non-isolated panels were tested under quasi-static cyclic loading. The results show that the proper behavior of this type of panel in isolated and non-isolated frames, the global stiffness of the frames and panels are reduced with a gentle slope, and brittle failure does not occur in the frames and panels. In the isolated specimens, the relative displacement (drift) of 1%, and the stiffness was 1.22 kN/mm. When the drift increased to 2.5%, the stiffness decreased to 0.88 kN/mm. In the non-isolated specimens, the drift of 1%, and the stiffness was 2.49 kN/mm. When the drift increased to 2.5%, the stiffness decreased to 0.89 kN/mm. The behavior of the non-isolated frame after loading is similar to the isolated frame because only the corners of the panel failed. A similar result was obtained in the failure pattern. In other words, the corners of the non-isolated panels attached to the frame failed by increasing the displacement due to in-plane infill-frame interaction. In the subsequent cycles, another part of the corners of the panels failed again. Complete failure was not observed in the panels. Similarly, in the non-isolated specimens, the panels remain without global failure after applying the cyclic load. The behavior of the non-isolated frame is similar to the isolated frame, with a decreased stiffness.

Reinforced Concrete (RC) Frames cover a large part of our country's structures. Neglect progressive collapse in this type of structures can lead to significant human and financial costs. Most of the regulations related to RC frames have comprehensive measures for resistance to seismic forces but there are only a few general solutions to increase the robustness to progressive collapse have been provided. In this study the effects of using High Performance Fiber Reinforced Cementitious Composite materials (HPFRCC) in the beam-column joints and the effects of its use on the robustness of RC frames against progressive collapse have been evaluated. For this purpose, after verifying the simulations with experimental tests using Opensees software the robustness of two 10-story RC frames under progressive collapse has been evaluated. The performance of the samples was measured using the robustness index proposed by Fascetti et al. The Fascetti robustness index is a combination of nonlinear dynamic and nonlinear static analyzes that evaluate the structural robustness to progressive collapse under multi columns removing scenario. The results of the sample analysis show the use of HPFRCCs materials in the joints beam-column can dramatically improve the robustness of concrete frames against progressive collapse by increasing the stiffness and ductility of the beam-column joints.

Risk assessment and prioritization is one of the most important components of risk management in any organization. Failure Mode and Effects Analysis (FMEA) is one of the most commonly used methods for assessment and prioritization of the multiple risks. Despite the widespread applications of this method in various industries, FMEA is associated with some shortcomings that can lead to unrealistic results. In this study, a new hybrid decision- making approach is presented in three phases to cover some of the shortcomings of the FMEA technique. In the first phase, based on the subject literature and getting help from a group of experts, 23 risks related to the construction project were identified and classified into six groups including technical, dynamics of the project environment, multiplicity of project stakeholders, employer, project management, and contractor. In the second phase, the fuzzy Stepwise Weight Assessment Ratio Analysis (SWARA) is used to measure the weights of decision criteria. In the third phase, the outputs of the previous phases are used as a basis to prioritize the risks using the Weighted Aggregated Sum Product Assessment (WASPAS) methods under fuzzy environment. To illustrate the potential benefits and applications of the proposed hybrid approach in a case study was implemented. The results obtained from the new hybrid approach to show that the low performance of the human resources, communication and cooperation of a poor contractor with another group, lack of proper management by the contractor regarding financial matters, supplier support, and subcontractors, and low performance of the human resources as the most important risks were recognized in the construction project of the Central Library of Markazi Province. Also, after performing the validation test and sensitivity analysis, it was found that the proposed method can provide valuable and effective information in helping to manage the risk of construction projects.

Hydraulic permeability of soil (k) is a critical parameter for mathematical modeling of groundwater and soil water flow. Due to the complexity of k  it is hard to gain a general empirical model which provides a reliable prediction of it. Therefore, this study used the Gene Expression Programming (GEP) model as a powerful data-driven technique for the estimation of k. The available published data for estimation of k  are culled from the literature. Six effective parameters including clay content (CC), water content (ω), liquid limit (LL), plastic limit (PL), specific density (γ), void ratio (e) were used to establish a predictive formula for estimation of k. Statistical parameters such as BIAS, Root Mean Square Error (RMSE), Scatter Index (SI), correlation coefficient (R), and Mean Absolute Error (MAE) were used for evaluating the accuracy of the developed GEP model. In addition, GEP findings were compared to Artificial Neural Network (ANN) to assess the performance of the GEP. The GEP with BIAS = -0.0005, RMSE = 0.0079, SI = 57.33%, R = 0.8109 and MAE = 0.0047 outperformed than ANN with BIAS = 0.001, RMSE = 0.0090, SI = 65.12%, R = 0.7490 and MAE = 0.0053 in predicting k in testing stage. GEP provided explicit mathematical equation can be utilized to determine k. Comparing the observed data and ANN results demonstrated that the GEP approach has suitable performance for prediction of k.

In this paper, a system dynamic model (SDM) has been created to predict the construction status in Iran using sustainable development indicators (SDI). The aim is to create a model based on system dynamics that would understand the complexities of the sustainable development system, as well as predict the values of variables and indicators used in the model for years to come. Since sustainable development involves various economic, social, and environmental aspects, the model has been formulated Using ten-year available data in these areas. After that, the output results of the model have been validated with reference patterns, and then, various scenarios have been created for sensitivity analysis. Finally, based on this model, the construction status in the Next years has become predictable. According to the results of this study, there is a direct and significant relationship between the amount of Construction and other indicators of sustainable development, such as the share of women working in the non-agricultural sector and the literacy rate of men aged 15-24.

Concrete has high compressive strength but has very low tensile strength, and relatively high fragility has made the tensile strength of concrete impossible in design regulations. The use of steel fibers in concrete matrices reduces the brittleness and fragility of concrete. Improving the mechanical properties makes the reinforced concrete matrix with metal fiber a suitable material for structural applications. In the present study, the mechanical properties of cement-based reinforced composites with different fiber volume percentages (1% and 2%) have been investigated. The cement-based matrix has a compressive strength of 64 MPa and fibers used by the Dramix family (3D, 4D, and 5D). In this study, to evaluate the flexural strength, a 4-point flexural test was performed on flexural elements reinforced with different percentages of steel fibers. Bending parameters such as displacement force diagram, crack state, energy absorption, and flexural stress are evaluated and compared. The results show that in some samples, the stiffening behavior occurs before the crack and rupture concentration, and then the strain-softening behavior. The occurrence of hardening behavior improves the mechanical properties of the material. In this case, the rupture of the specimens occurs through the creation of multiple cracks.

The moment frame system is used as a lateral load resisting system against seismic loads. So far, a large body of research has been conducted on steel connections and various types of connections including Reduced Beam Section (RBS) and Drilled Flange Connection (DFC). Using RBS results in the formation of inelastic deformation in a part of the beam far from the column flange. They have studied the seismic performance of the recently developed DFC as a simple and efficient alternative to mostly used conventional RBS. In this research, the beam flange is drilled in different patterns in terms of the hole diameter. After simulating the models in Abaqus, the moment-rotation curves are extracted and analyzed numerically. Having obtained the results of the current research regarding the moment connection where beam flanges are drilled, it is evident that drilling holes in the beam flange with a clock pattern can better satisfy the flexibility expectations. Moreover, this pattern has the higher capability for plastic hinge transfer from the column face compared to the direct pattern. Additionally, this pattern can reduce the bending stress in the penetration weld of the direct beam to column connection. Thus, the clock pattern of beam flange holes performs better than the straight one.

By increasing the demolition of old concrete structures and the interest of civil industries to consume cheaper materials, using Recycled Concrete Aggregate (RCA) can cause environmental protection and decrease the construction costs. On the other hand, the high potential of Recycled Aggregate Concrete (RAC) in concrete industry was established by extensive experimental researches were performed to examine the properties of RAC. Like in conventional concrete, core test cut from RAC can be used to assess the in-place concrete compressive strength and sometimes it becomes an important test for monitoring in-situ properties of concrete to taking up retrofitting/strengthening measures. So the core test is often mentioned in most codes for concrete testing. The layout of this study includes four concrete mixes, two concrete grades (20 and 40 MPa), three core diameters (46, 69, and 100 mm), five length-to-diameter (L/D) ratios (1, 1.25, 1.5, 1.75, and 2), two sizes of maximum coarse recycled aggregates (10 and 20 mm), two directions of core drilling which are vertical and horizontal and three ages of the specimen (14, 28 and 90 days). The core test results were compared to cylindrical and cube specimens. Results imply that the core strength of recycled concrete reduces with the increase in aspect ratio, by decreasing the core diameter, increasing the size of coarse aggregates in recycled concrete. By analyzing the results a comparison was made between recycled concrete in this study and conventional concrete in other studies, as well as code instructions.

Performance-Based Earthquake Engineering (PBEE) attempts to improve seismic risk through assessment and design methods that are more informative than current approaches. However, little work has been performed investigating the seismic response of buried steel pipelines within a performance-based framework. In this paper the seismic response of buried steel pipelines are studied in a performance-based context. Multiple nonlinear dynamic analyses of three buried steel pipes with different D/t and H/D ratios, steel grade and various soil characteristics carried out using an ensemble of near-field ground motion records were scaled to various intensities to capture the behavior of buried pipeline in the range of elastic response to dynamic instability. Peak axial compressive strain in critical section of the pipe was considered as engineering demand parameter (EDP) of pipelines. Several ground motion intensity measures (IMs) are considered to investigate their correlation with EDP. Using the regression analysis in logarithmic space the efficiency and sufficiency of investigated IMs are studied.Among the models investigated in this study it was seen that VSI[w1(PGD+RMSd)]^0.5 , PGV and SMV are the most sufficient IMS. For buried steel pipelines investigated in the studied it was concludede that PGD is the most sufficent IM for near-field fround motions. It was seen that VSI[w1(PGD+RMSd)]^0.5 followed by SMV are the optimal IM for buried steel pipelines under near-field ground motions based on both efficiency and sufficiency conceptions.