نشریه مهندسی سازه و ساخت
سال دهم شماره 8 (پیاپی 73، آبان 1402)

With the increasing cost of petrol for Iranian customers, the interest in using dual fuel cars is increasing widely. It is common to use CNG vessels in Iranian dual-fuel cars. Nowadays there are millions of CNG vessels with more than 10 years of Commissioning time in Iran. In this study, the burst CNG car tank performance of steel reinforced concrete (RC) columns was numerically investigated with Abaqus software; and using Phast software for modeling equivalent TNT force exertion. Recently, the number of explosions of CNG tanks is increasing which has caused a lot of casualties and financial losses. In this study, the effect of CNG tank explosion on the Reinforced concrete column was investigated by considering four variables, including the distance between the CNG tank and column, reduction of the resistance of the car body, strength of concrete, and dimensions of the column’s section. Investigations showed that the most effective parameters according to the changes of the examined parameters are 1) distance between CNG tank and column and reduction of the resistance of the car body 2) section area of a column and 3) strength of concrete as, by increasing distance from 50 to 130-centimeter the maximum displacement decreased 63 %, by decrease the resistance of the automobile body to 80% the maximum displacement decreased 64%, by change strength of concrete from 20 to 40 Mpa the maximum displacement decreased 15% and by increase section from 35×35 to 50×50 cm2 the maximum displacement decreased 45%.

Increasing the productivity of human resources is one of the main plans of managers in every organization because human resources are the most important capital of every organization. Human resource productivity means the maximum use of skills and human resources. In this research, six functions of recruitment, job analysis, education, performance evaluation, work relationships, and employee services are considered effective factors in human resource management to increase the productivity of human resources. Also, the two variables of job ability and job motivation are also considered mediating variables. The current research is practical in terms of purpose, in terms of the nature of the research, it is descriptive, in terms of data application method, it is part of survey descriptive methods, and in terms of the research implementation process, it is qualitative. In this research, library studies and questionnaires were used to collect information. The statistical population of the research is all employees of contracting companies with grades one to five, numbering 150 people. In this research, the data were analyzed using the structural equation method with the partial least squares approach and using PLS software. The results of this research show that among the six functions of human resources management, the independent variables of job analysis and employee services have the greatest impact and the independent variable of performance evaluation has the least impact on the mediating variable of job motivation. Also, the two independent variables of recruitment and employment services have the greatest impact and the independent variable of job analysis has the least impact on the mediating variable of job ability. As a result, among the two mediating variables of job ability and job motivation, the variable of individual performance is more dependent on job ability.

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.

The Use Of Color Spectrums In The Urban Space Can Be Seen In The Facades Of Buildings, Flooring, Urban Furniture, Sidewalks And Streets. The Use Of Colored Concrete For Facade Construction And Decoration Design Can Be Welcomed For Many Reasons. Also, This Method Does Not Require The Use Of Other Materials To Cover The Work, In Which Case The Costs Of Facade Work Will Be Significantly Reduced. But Temperature Changes And The Cycle Of Melting And Freezing In Unstable Environmental Conditions Is One Of The Factors Of Concrete Failure. Therefore, In Addition To Beauty, Colored Concrete Must Be Resistant To Different Environmental And Atmospheric Conditions. Yellow Is One Of The Three Main Colors In The Color Wheel. In Architecture, Yellow Is A Practical Color And It Makes Spaces Appear Bright And Large Due To The Large Amount Of Light It Reflects. The Pigment Of Mung Bean Or Limonite Is A Type Of Mineral Soil That Has A Large Amount Of Iron Oxide. This Pigment Is Found In Dull Yellow Or Mustard Colors. In This Research, To Change The Color Of Concrete To Yellow, White Cement And Limonite Pigment Were Used In Different Weight Ratios Of 5%, 10%, 15% And 20% In Concrete. Further, To Check The Behavior And Durability Of Concrete, Compressive Strength Tests, Water Absorption In Hardened Concrete, And Durability Of Melting And Freezing Were Investigated. The Results Of This Research Showed That The Colorability Of 5% And 10% Limonite In Concrete Will Cause Pea And Cream Color And The Use Of 15% And 20% Will Cause Yellow Color. Also, The Use Of 10% Limonite In Concrete Increased The 28-Day Compressive Strength By 8%. But Due To The High Water Absorption Of Limonite, Its Freezing Durability Decreased Compared To The Control Sample.

The expansion of cities and the increase in the price of land has caused an increase in the number of underground floors and the depth of excavation, and considering that ensuring safety in excavation workshops, in addition to ensuring the health of employees, leads to an increase in the quality of the project, therefore, one of the important issues in urban construction and structures. Is to create proper stability during excavation, excavation is one of the dangerous earth operations. According to available statistics, many people lose their lives every year in excavation projects due to non-compliance with safety principles. In this research, first by conducting library studies, a list of effective risks in sustainable urban deep pit projects was prepared using the strut method, and experts' opinions were collected through a questionnaire and analyzed in SPSS software. Then the decision matrix was formed based on the desired indicators and criteria and were ranked using a questionnaire and based on the criteria of "level of influence", "level of importance" and "existence of necessary tools." Execution for wide pits", "Execution limitation in projects with irregular geometry or geometry", "Inability to use to increase the depth of the pit during execution or after the completion of excavation", "Too much settling in the pit and causing disturbance to the implementation of the foundation and structure", "the possibility of equipment and machinery colliding with the elements and putting them at risk", "collapse of walls and elements falling", "increasing the cost of implementation in deep pits and large fields compared to usual methods", "increasing Implementation time in deep pits and large fields compared to usual methods", "Falling from a height during work on connections", "need for strict quality control to implement restraints, especially connections" have the highest impact, respectively.

In this paper, a new and efficient performance-based method is introduced for the optimal design of the tuned mass damper (TMD) to control the response of nonlinear structures. In this method, the FEMA-P58 probabilistic evaluation framework is used in the design and evaluation of TMD performance in order to reduce the repair cost and time caused by structural and non-structural damages. For this purpose, an innovative objective function has been defined based on structural responses resulting from different earthquakes, which is compatible with the probability of the repair cost and time exceeding a certain value in the FEMA-P58 method. Uncertainties due to earthquake records are directly considered in the introduced objective function. The genetic algorithm is used for the optimal design of TMD based on the proposed objective function. Also, due to the fact that considering the uncertainties in the input earthquake records leads to increasing the calculation time, therefore the artificial neural network technique is used as a fast estimator of the nonlinear dynamic response of the structure to reduce the calculation time. The probabilistic evaluation of the performance of the structure equipped with the proposed TMD shows the efficiency and effectiveness of the proposed design procedure in reducing the expected repair cost and time. So that the expected repair cost and time in the structure equipped with the proposed TMD under the design earthquake have been reduced by about 29% compared to the uncontrolled structure.

This paper is devoted to investigating the effect of applied torsional moment on the out-of-plane behavior of horizontally curved beams (HCBs) subjected to the excitation induced by a moving mass. As the mass travels along the top surface of HCBs, a torsional moment will be introduced into the system due to the eccentricity of the in-plane centrifugal action with respect to the shear center of the HCB section. The differential equations governing the HCB-moving mass system are first established considering the effect of mass inertia, Coriolis and centrifugal forces, and then numerically solved within the transition matrix approach. Thereafter, a parametric study is conducted to evaluate the influence of radius of curvature and central subtended angle of HCB, as well as the mass and velocity of the moving object. In general, with an increase in the values of radius of curvature and subtended angle of HCBs, a decreasing effect in the response of the system is observed. Moreover, a general magnifying effect is essentially experienced due to an increase in the mass and velocity of the moving object. As the results suggest, the magnifying effect of the induced torsional moment due to the in-plane centrifugal force is at most six percent for the results studied herein. For long-span HCBs, the torsional effect can be deemed as insignificant on the out-of-plane response of HCB-moving mass systems. In conclusion, it is indicated that considering the contribution of the torsional moment can offer a more realistic response estimation regarding the dynamics of HCBs acted upon by a moving inertial load.

The occurrence of fire in structures is a possible phenomenon that can significantly affect the mechanical properties of the materials of structural members. Nowadays, the use of new materials and additives in concrete construction has been considered, and it is necessary to examine the strength of concrete made with these materials during and after fires and to ensure its proper behavior. In this research, microsilica, as a very effective pozzolanic material and polypropylene fibers as a material to improve cracking resistance were used to make concrete. The behavior of concrete specimens with different values of these additives after exposure to high heat was investigated in the form of tensile and compressive strength tests. The control concrete specimen was considered for comparison with other specimens where the compressive strength of this specimen was 30 MPa. In addition to the control specimen mixing design, 11 other mixing designs were made with propylene fibers in the amount of 0.05, 0.075 and 0.1% of the weight of concrete and microsilica in the amount of 5%, 10% and 15% of the weight of cement. The specimens were placed in an oven at 600 ° C for one hour. After cooling, compressive and tensile strength tests were performed on the specimens. The results showed that the combination of polypropylene and microsilica fibers increased the tensile strength, the maximum increase was 82% compared to the control specimen. The maximum increase in compressive strength compared to the control specimen was 63.4%. After exposure to heat, the tensile strength of the proposed sample increased by 44% compared to the control specimen.

Recently, Colored Concrete Is Used In Many Countries For Aesthetic Purposes. This Made The Gray Color Of Ordinary Concrete Less And The Surroundings More Beautiful. Colored Concrete Is Used In The Construction Of Floors. Colored Concrete Floors Can Be Considered A Better Alternative To Old Floors. Because It Reduces Costs, Reduces Materials And Manpower, Reduces Weight And Reduces Environmental Risks. In This Research, To Make Red Concrete, Okhra Powder Was Used In The Amount Of 2.5%, 5%, 7.5% And 10% By Weight Instead Of Part Of Cement. Also, To Strengthen The Wear Resistance Of Concrete, Nano Aluminum Oxide Powder Was Used In The Amount Of 0.5% By Weight Of Cement. Next, To Reduce The Cost And Ease Of Implementation, A Coating Layer Of Mixed Okhra And Nano-Aluminum Was Used On The Concrete Surface And Its Results Were Compared. The Results Of This Research Showed That Okhra Colored Soil Will Reduce The Wear Durability Of Concrete, But Its Combination With Nano Aluminum Powder Can Significantly Increase The Wear Durability While Maintaining The Quality Of Concrete Color. Also, Creating A Colored Coating Layer On The Surface Of The Concrete Is Less Effective Compared To The Mixed Design, So That The Use Of This Method Can Reduce The Wear Resistance Of Concrete By 40%.

The definition of regularity is different as it has different goals. Most engineers agree that a space structure is regular if a high percentage of its elements (sides) are equal or almost equal. There are several ways for improving regularity of the space structures, In this regard, Professor Nooshin et al used methods such as Traviation Process, Stepping Projection, Recursive techniques and etc to create a special category of structures (domes and flats) and they presented grid shells that were designed in a multimodal way. They defined regularity indicators quantitatively which are known as degrees of regularity or geometric parameters or regularity measuring meters. The regularity in this research is related to the increase of elements with equal or almost equal length, reduction the number of elements with different lengths, and the reduction of the number of length intervals while maintaining the geometry of the form. The freeform space structure of Ati Center were designed by the engineers of the Ofogh Noor Space Structures Company by using a single layer grid in Rhino software. This study aims to investigate the previous regularity indicators and improving regularity of this structure with triangulation techniques and proposed algorithm which is the optimization of Delaunay triangulation obtained from 176 random points with the help of circle packing algorithm and octopus optimization to reach a suitable pattern. Also we have presented algorithms to calculate the regularity indices and we have calculated them for each structure, investigated the improving regularity and we have suggested the general definition of regularity index and we have shown that the definitions of regularity indices alone are not the basis for evaluating the regularity of two structures. So a unique definition is needed. The result of this research is effective in solving problems related to form selection, improving regularity.

Regarding the possibility of lifetime reduction of the structure due to different factors, including cracking and phenomena, such as earthquakes, it is crucial to constantly monitor the structure so that the location and severity of the damage can be timely identified to correctly estimate the remaining lifetime of the structure. Wavelet transform is a robust tool for identifying local structural damages, by which the damage location is identified by observing a disturbance in the wavelet coefficients of the damaged structure, regardless of the main (undamaged) structure response. This paper addresses the application of wavelet transforms for identifying multiple cracks in steel moment resisting frames, which has received less attention in the literature. To this end, different crack modes were considered in the form of element removal for one-story and two-story frames, and the first four mode shapes of the damaged structure were derived using the ABAQUS. Finally, the derived mode shapes were subjected to continuous coif5 and sym2 wavelet transform, and the capability of the method in identifying cracks in structures accounting for the effect of mode order and damage location was evaluated. The results indicated that if the proper wavelet was selected, the proposed method would be able to identify the damage location based on the response signal using a simple, robust, and reliable way. The results also showed that the damage in the beam was identified with a higher accuracy than the column foot. It was also shown that the location of the damage in the mid-span of the beam can be identified with a higher accuracy than the damage near to the column abutments. Also, it was observed that higher modes could identify the damage location with a higher resolution.

One of the important parameters in the process of calculating the basic shear force in the direct design method based on displacement is the estimation of the displacement displacement based on the geometric characteristics of the structure. In this article, an attempt has been made to investigate the relationship between displacement and yield of steel structures with elliptical bracing in the direct design process based on displacement. For this purpose, 24 models of bending frames with oval braces with different number of floors 6, 9, 12 and 15 floors, with different number of openings 3 and 6 openings have been studied. The various analyzes performed include non-linear static analyses, non-linear dynamic analyzes with seven artificial acceleration maps and seven natural acceleration maps according to the design spectrum of the structures. SAP2000 software has been used for the design and analysis. The obtained results show that for structures with 6 floors and above, this relationship should be reduced by 30%.The basic philosophy in the displacement-based direct design method is that structures should be designed to achieve a specified level of performance, this performance level can be defined by specifying strain limits or relative lateral displacement under the effect of specific hazard levels. In fact, this method can be considered a step-by-step method leading to the limit forces of the members. In this method, instead of using the characteristics of the original multi-degree-of-freedom structure, an alternative single-degree-of-freedom structure with inelastic characteristics of the original structure is used.