نشریه مهندسی سازه و ساخت
سال دهم شماره 4 (پیاپی 69، تیر 1402)

The bus rapid transit (BRT) network is an important public transportation system in some metropolises across the world. Hence, many urban managers and planners seek to develop BRT networks as they are more much flexible than railway transportation networks and can transport huge numbers of passengers. This paper designed a BRT network based on the travel demand using a binary nonlinear mathematical programming model with the aim of maximizing the covered demand and minimizing the construction cost. To calculate the covered travel demand and solve the model, a novel methodology which is exclusive to this study was proposed. To obtain the covered travel demand, the number of covered travels was calculated using the concentric circle method and the center of mass distances of the covered trips in the origins and destinations from the travel start and end stations. Based on the trip demand lines, major production and attraction land-uses, and network shape and integration, five BRT corridors were considered for the city of Karaj, Iran. The network design results suggest that the corridors would cover a total of 244,600 trips (28.7% of the total morning peak-hour trips in 2031). The corridors were estimated to have a total construction cost of 282.5 million USD.

Recent studies have clearly demonstrated this fact motivation is directly linked to increased productivity in human resources. Therefore paying attention to employees' motivational factors and their needs is important to ensuring productivity and performance improvement of organizational projects. In a few researches the motivation of human resources and the effect of different factors on the change of motivation and its effect on the time productivity of construction projects have received less attention. Therefore, the aim of this article is to investigate the effect of change of motivation and the factors affecting it on the time efficiency of construction projects with the approach of system dynamics. For this purpose, after identifying the effective parameters on the motivation of human resources, from sampling data using survey studies with questionnaires and interviews, library sources and collecting information. the qualitative modeling and effect loops between parameters were performed with the Vensim software package. Also, the relationships between parameters were determined with the quantitative modeling. In the following, the model was implemented to the real project by defining different scenarios based on changing the effective parameters on the motivation of manpower and the time efficiency of office-commercial building project. The results showed that if there is a 50% increase in manpower motivation in the project, the correct rate of work is increased up to 3 times and the project takes 690 days and 30 days. The results also show that a 50% reduction in salary increases the delay in completing the project by about one year and a 20% delay in payment of salaries leads to an increase in project completion of up to 4 months and an increase in the ratio parameter. Wages will be reduced by up to 2 times 5 months after the completion of the project.

Considering that in recent decades, the discussion of earthquake engineering for better understanding of earthquakes and their destructive effects on structures built in seismic areas has made significant progress, which has led to changes in building design regulations against earthquakes. In some cases, structures designed based on initial revisions of seismic codes and standards have lower seismic resistance than structures designed with newer revisions. As a result, constructed structures need to be retrofitted. In this paper, the reduction of seismic damage of six-stories steel moment frames having CLT infill walls has been investigated. The system is modeled with ABAQUS software. The S4R element has been used to model steel beams and columns with a yield strength of 350 MPa. Cross-sectional vertical panels with C3D8 R element according to NDS 2018 are modeled elastically in the software. Contact modeling was performed between the vertical panel with the steel frame by assigning the behavior of the Hard Contact type in the direction perpendicular to the plates in contact with each other and the Tangential type in the direction of the tangent of the two plates with friction coefficient. Also, the gap between the steel frame and the CLT is crossed to deform the brackets during an earthquake to dissipate the earthquake energy during the vibration. Frame behavior has been investigated using incremental dynamic analysis. The results showed that CLT infill walls play a major role in reducing maximum inter-story drift and various structural damages. The results also showed that the addition of CLT infill walls reduces the possibility of the collapse of the structure at various damages.

The purpose of this paper is to propose new formulas for optimal tuning of tuned mass damper (TMD) parameters using the genetic programming (GP) method with the aim of its application in seismic-excited structures. For this purpose, the optimal TMD parameters in the main structure under white-noise base acceleration are determined using the teaching-learning-based optimization (TLBO) algorithm for a wide range of TMD mass ratios and structural damping ratios. The outcome database is then applied to derive formulas based on the GP technique. The proposed formulas have high accuracy and efficiency while eliminating computational costs. Considering two 10-story and 40-story structures, the efficiency of the proposed formulas is then evaluated for seismic control applications of structures. For this purpose, their results are compared with those given by the TLBO algorithm. The numerical studies show that the optimal tuning of TMD parameters using the proposed formulas, while eliminating the computational cost due to the use of meta-heuristic optimization algorithms, provides better performance in reducing the floor displacement and absolute acceleration of the studied structures. Consequently, they can be efficient for seismic control applications of structures by presenting a simple and fast optimal tuning. The TMD tuned using the TLBO results in a reduction of 18.03%, 6.72% in the maximum displacement and acceleration of the 10-story structure, while the TMD adjusted using the proposed formulas gives a reduction of 18.47% and 11.23% in the above-mentioned responses. The results given for the 40-story structure show a reduction of 9.46% and 0.98% for the TMD tuned by the TLBO, while it is found a reduction of 11.58% and 5.1%% in the maximum displacement and acceleration for the TMD tuned by the suggested formulas.

In this study, the effect of pulse like and non-pulsed near field records on the displacement and axial force of the nail in the soil nail wall has been investigated. Pulse liked records are created under physical factors such as the effect of Forward directivity, Fling Step, the effect Hanging wall, etc., A pulse has a large amplitude with medium to long period, which contains most of the energy due to fault rupture. It has been used to investigate the effects of near-field records by the finite element method and by using the HSS behavioral model due to considering the effect of small strains and hysteresis damping. In this research, Song and Rodrigues seismic bank in 2015 including 62 pulsed and non-pulsed near field records has been used. The obtained results showed that the soil nailed walls have good performance against seismic loads. pulsed records have a direct effect on the axial force and displacement of the nailed wall, also the axial force of the nails and displacements in the pulsed records have a good correlation with the PGV (peak ground velocity) parameter, the axial force of the nails in the non-pulsed records with the parameter It had Ia (Arias intensity) and non-pulse displacement with seismic parameter PGV.

Seismic resilience of a structure is defined as the ability of the system to maintain its functionality and to quickly return the damaged system to the required functionality. In this approach, system performance is evaluated through a unique decision variable called "resilience" which includes a combination of several variables (economic losses, casualties, reconstruction time, etc.). In the present study, a method for calculating the expected seismic resistance of buildings is presented. In the proposed method, it is assumed that the amount of reduction in the performance of the system is proportional to the direct economic damage to the structural and non-structural elements. The recovery cost and time of the structural and non-structural elements are calculated using FEMA-P58 library data and the reconstruction time of the whole building is calculated based on the order of the proposed reconstruction operations in the REDi instruction. The proposed method is applied to 9-storey buildings with Per-Northridge and Post-Northridge steel moment frames and expected recovery cost, expected recovery time and the expected seismic resilience for the two buildings are compared. The total recovery time according to REDi method is very different from the total recovery time provided by FEMA P58 and should be seriously considered in calculating the cost-time curve and resilience of different systems. It is also observed that using Post-Northridge connections in comparison with Pre-Northridge connections, significantly reduces the recovery costs and time, and thus increases seismic resilience.

The fly ash obtained from the extraction of exhaust gases from coal and silt furnaces, is non-plastic and fine, which is a different combination based on natural coal fuel. Fly ash is one of the waste materials in thermal power plants. The use of waste materials such as fly ash in the concrete industry offers an alternative and valuable solution to create an environmentally friendly environment. However, experimental work is time-consuming and expensive, and the use of soft computing techniques can speed up the process of predicting concrete's resistance properties. In this study, artificial neural network (ANN) was used to predict the compressive strength of fly ash-based high-performance concrete. A number of 471 experimental data were extracted from valid sources and parameters such as cement, fly ash, water, superplasticizer, fine and coarse aggregate and age of the samples were considered as input parameters and compressive strength of samples was considered as output parameters. Among the networks with different number of neurons, a network which has the best correlation coefficient values obtained from training, evaluation and testing data and also has the lowest mean square error (MSE) value was selected as the optimal network. In this study, the network with the number of 6 neurons provided the best results. Also, the effect of each parameter in different numerical ranges on the compressive strength of concrete was investigated and presented, and it was found that the age of the samples and the amount of cement, fly ash and water have the greatest relative importance.

Soil shear strength is affected by various factors such as grading, compaction percent of materials, vertical load level, shear rate and other factors. When placing soil and other material in the vicinity , the interaction problem is discussed . Such conditions are observed in embankment dams with asphalt concrete cores, in which determining the mechanical performance of the interfacing materials has great importance. In this research, a laboratory study has been conducted to characterize the interface behavior of soil materials of filter and asphalt concrete in the core, through direct shear test. For this purpose, specimens containing soil materials from classes GC and GP at the same relative density were tested under different shear rates and the strength parameters were determined. On the other hand, for considering the impact of the relative density of the materials on strength characteristics, specimens containing materials from GP class at both medium and high relative densities were tested at different shear rates and the desired parameters were determined. Based on the results, in GC interface materials, the interaction ratio has diminished at small shear rates and increased at elevated shear rates. The amount of increase and decrease of the interaction ratio was equal to 2.36 percent. In GP interface materials, the ratio of interaction has increased by 2.3% with a higher shear rate. Also, for constant shear rates, increasing the compaction percent of materials from GP class in the interface, from medium to high level, has resulted to reduced interaction ratio. Increasing the shear rate in materials with moderate and high relative density also followed, respectively, the increase and decrease of the interaction ratio .

The superelastic viscous damper (SVD) relies on shape memory alloy (SMA) cables for re-centering capability and employs a viscoelastic (VE) damper that consists of two layers of a high damped (HD) blended butyl elastomer compound to augment its energy dissipation capacity. An analytical model of a five-story and nine-story steel special moment frames building with the installed SVDs and BRBs are developed to determine the dynamic response of the structure. Nonlinear response history analyses are conducted to evaluate the behavior of controlled and uncontrolled buildings under 44 ground motion records. All the buildings are subjected to incremental dynamic analysis (IDA), so the effects of SMA on seismic performance of the buildings would be investigated through seismic concepts. Based on the results, utilizing SMA connections in smart buildings not only could keep interstory drift control performance almost similar to conventional buildings but also could substantially reduce economic loss with significant control of unwanted residual deformations in structural fuses due to their unique ability of induced recentering behavior in structural performance. The results probabilistically determine the seismic performance acceptability of studied smart buildings based on the impact of key structural response parameters (i.e., maximum interstory drift, residual interstory drift, and energy dissipation) on the seismic performance of the structure.

Lake Urmia is the largest lake in the country and the second saltiest lake in the world. The implementation of administrative and agricultural development plans affects the water resources of the Urmia Lake catchment and its ecosystem; which requires study and research. Estimating the environmental needs of the lake and taking it into account in the development plans of the watershed can lead to the protection of its ecological and hydrological functions. In this article, WEAP, a comprehensive and integrated planning tool for water resources, was used to investigate the response to meeting the environmental needs of the lake. In order to realize this goal, initial simulation was done in a period of 13 years (2007-2020), then in line with the goal of the research, a scenario was created in a period of 30 years (2021-2050). The built model was evaluated with statistical indices of regression fit (R2), Nash-Sutcliffe index (NSE), root mean square error (RMSE); whose values ​​were better estimated as 0.99, 0.78, 0.871 cubic meters per second; which show the acceptable error rate of the model. The results showed: the average monthly volume of water entering the modeling area in the hot summer months compared to other months has significantly decreased, the reason for this is the decrease in surface and underground runoff, the development of agriculture and the increase in population, the decrease in water consumption efficiency and the decrease in agricultural return flows. The development of unorganized management plans, the reduction of rainfall and the high rate of evaporation in hot seasons; which requires proper management and formulation of strategic development plans with the perspective of environmental protection and especially preservation and restoration of Lake Urmia.

In the present study, the effect of recycled glass fibers on the behavior and mechanical properties of concrete was investigated. The research was conducted by laboratory study method. Various cubic and cylindrical samples were made in the laboratory. In all mixing designs, the water to cement ratio was 0.35 and the sand to cement ratio was 1. First, a reference sample without fibers and additives was prepared and subjected to various tests. Examination of the samples after the experiment showed that failure occurred in the samples without recycled fibers and brittle glass waste; But failure in samples reinforced with recycled fibers and glass waste is gradual. Under these conditions, in samples made by spray method, the modulus of rupture and displacement of samples to the moment of failure, had much higher values ​​than samples made in the pre-mixed method. As the age of the samples increased from 7 days to 90 days, the modulus of specific rupture of the cement decreased; However, there is no definite trend in changes in the specific rupture modulus of the pozzolanic effect over time. According to the results, it can be seen that over time from 7 to 28 days, the specific compressive strength of cement and also the specific compressive strength of the pozzolanic effect has increased. Over time from 7 to 28 days, the specific compressive strength of cement as well as the specific compressive strength of the pozzolanic effect has increased.

It is difficult to determine the real strength of concrete in an existing structure because it depends on curing type record, concrete compaction quality, and pouring of concrete method. A core test is the most effective and reliable way to measure the concrete characteristics of the structure. The cores provide reliable and useful results because they are mechanically tested up to the destruction stage. The use of rebar in the concrete core samples tested in the parts of the reinforced concrete that have bar compaction is unavoidable. In most codes, using rebar is ignored, and the other factors are considered adequate on core test results; it has just been discussed and suggested to ignore the cores, including rebar. Therefore, this research aims to survey about the effect of using bars on the strength of concrete cores. In this regard, variables such as length to diameter (L/D) ratio of core, core diameter, the diameter of steel bar, number of steel bars, steel bars’ order, the configuration method of rebar, the distance of bar axis from the nearer end of the core, the moisture condition and water to cement ratio (concrete strength level) are considered. In the first step, concrete samples, including rebar, were tested with a concrete core. The examined samples were validated using numerical studies and ANSYS software; then about 200 cylindrical core samples using this software were studied in order to determine the pressure drag and also the effective parameters on the behavior of cylindrical concrete core containing rebar, and the results including the pressure drag and collapse mechanism were investigated and compared. Using rebar in the cores plays an important role in the stress and strain variation of the concrete core and the bars inside