| 5391. |
- Bahrami, Alireza, et al.
(författare)
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Dynamic analysis of steel eccentrically braced frames with shear link
- 2020
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Ingår i: International Journal of Engineering Research and Technology. - : International Research Publication House. - 0974-3154. ; 13:2, s. 233-239
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Tidskriftsartikel (refereegranskat)abstract
- This paper offers the dynamic analysis of steel eccentrically braced frames (EBFs) with shear link under earthquake loads. The analysis was carried out using the finite element software ABAQUS. The verification of the EBF modelling was established by the comparison of the modelling result with that of the experimental test. Then, an EBF was designed with a shear link. Three different severe earthquake records of Tabas, Northridge, and Chi-Chi were selected for the analyses. Since the modelling accuracy was revealed, the method was utilised for modelling the developed EBF. The EBF was then analysed under the mentioned records. From the obtained results, the lateral displacements and energy dissipations of the frame and also shear link rotations were investigated. With regard to all the effects of the records as the lateral displacement and base shear of the frame and also the shear link rotation, it was found that the hierarchy of the records from their effects viewpoint on the EBF has been the Tabas, Chi-Chi, and Northridge earthquakes. In addition, the hierarchy of the energy dissipations of the records by the EBF has been the Tabas, Chi-Chi, and Northridge earthquakes, as well. Therefore, the developed EBF demonstrated a good performance in the energy dissipation of the earthquake records.
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| 5392. |
- Bahrami, Alireza, et al.
(författare)
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Dynamic behaviour of steel eccentrically braced frames having moment-shear link
- 2020
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Ingår i: Journal of Engineering and Applied Sciences. - : Asian Research Publishing Network. - 1819-6608. ; 15:23, s. 2793-2799
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Tidskriftsartikel (refereegranskat)abstract
- This research is concerned with the dynamic behaviour of steel eccentrically braced frames (EBFs) having moment-shear link. The finite element software ABAQUS is used to analyse the EBFs. An experimentally tested EBF is modelled and the comparison of its obtained result with that of the experimental test validates the modelling method. An EBF is also designed having a moment-shear link. The designed EBF is modelled based on the verified modelling method. Then, the EBF is analysed under three selected earthquake records of Tabas, Chi-Chi, and Northridge. The lateral displacements, base shears, and energy dissipations of the EBF and also moment-shear link rotations are obtained from the results and compared. It is concluded that the largest to smallest values for the lateral displacement and base shear of the EBF, and also link rotation are all related to the Tabas, Chi-Chi, and Northridge records, respectively. However, the EBF dissipates the energy of the Tabas record more than the Northridge record, while, the latter is more than the Chi-Chi record.
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| 5393. |
- Bahrami, Alireza, et al.
(författare)
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Effectiveness of composite steel-concrete buckling-restrained braces (BRBs) for steel frames
- 2021
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Ingår i: International Journal of Advanced Research in Engineering and Technology. - : IAEME Publication. - 0976-6480 .- 0976-6499. ; 12:3, s. 42-55
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Tidskriftsartikel (refereegranskat)abstract
- Effectiveness of composite steel-concrete buckling-restrained braces (BRBs) for steel frames is assessed in this paper. The buckling-restrained braced frames (BRBFs) are investigated by employing the ABAQUS software. This software uses the finite element method. A BRB which has been tested experimentally is modelled in this research in order to verify the modelling. Then, the result of the modelling is compared with that of the experimental test. Since there is a good agreement between the results, the verification of the modelling is accomplished. A BRBF is subsequently designed having moment-shear link. The dynamic analyses of the BRBF with moment-shear link are conducted under three different earthquake records of Tabas, Chi-Chi, and Northridge. The obtained results from the analyses include the lateral displacements, base shears, and energy dissipations of the BRBF and also moment-shear link rotations. These results are compared and discussed. The achieved results from the analyses of the BRBF are also compared with those of its corresponding steel eccentrically braced frame (EBF). The results signify the effectiveness of the BRBF having moment-shear link over the EBF with regard to the lateral displacement, base shear, energy dissipation, and link rotation.
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| 5394. |
- Bahrami, Alireza, et al.
(författare)
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Energy absorption capacity of concrete-filled steel tube slender columns with different aspect ratios
- 2022
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Ingår i: Current Applied Science and Technology. - : King Mongkut's Institute of Technology Ladkrabang. - 2586-9396. ; 22:1, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- The present paper examines the energy absorption capacity of concrete-filled steel tube slender (CFTS) columns having different aspect ratios. The CFTS columns are nonlinearly analysed employing the finite element software ABAQUS. In order to validate the simulation of the columns, an experimentally tested CFTS column is simulated and its achieved result is compared with that of the tested column. Since it is concluded that there is a good agreement between the obtained results from the simulation and experimental test, the validation of the simulation is then established. The simulated columns are thereafter developed using different aspect ratios of 6, 10, and 13 and also considering the following parameters: load eccentricities, cross-sectional shapes, and steel tube thicknesses. The columns are nonlinearly analysed and the results are achieved from the analyses. The effects of the above-mentioned parameters on the energy absorption capacity of the CFTS columns are evaluated. From the results, it can be concluded that the energy absorption capacity of the columns is decreased by the increase of the load eccentricity or aspect ratio. Further, the energy absorption capacity of the circular CFTS column is greater than that of the rectangular and square CFTS columns. However, higher energy absorption capacity is accomplished for the rectangular column than the square column. Additionally, increasing the steel tube thickness leads to greater energy absorption capacity of the columns. Typical failure modes of the columns are assessed.
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| 5395. |
- Bahrami, Alireza, et al.
(författare)
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Energy Audit of Two Multifamily Buildings and Economic Evaluation of Possible Improvements
- 2023
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Ingår i: Urban Transition. - : IntechOpen.
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Bokkapitel (refereegranskat)abstract
- AbstractThe energy use of buildings is gradually increasing, which is due to economic growth and an increase in population. Several studies have indicated that the implementation of energy-saving measures (ESMs) such as thermal insulation results in more energy saving; however, most ESMs are not economically viable. This chapter outlines ESMs using the IDA ICE computer software. The evaluation of the energy performance of two multifamily buildings is conducted, and possible ESMs are suggested such as thermal insulation, changing windows, installing a new air handling unit, installing a heat exchanger in showers, improving thermal bridges, replacing lighting bulbs, increasing external insulation plus temperature reduction, and changing schedules for air discharge control. The economic feasibility of these suggestions is assessed using the life cycle cost analysis to determine their economic viability. This involves the determination of the life cycle cost and life cycle cost saving to decide the best option. The most important factor in determining life cycle cost saving is the modified uniform present value. The addition of the attic insulation, installing a heat exchanger in showers, replacing lighting bulbs, and changing schedules meet the economic requirement within a feasible time frame.
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| 5396. |
- Bahrami, Alireza, et al.
(författare)
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Evaluation of structural response of composite steel-concrete eccentrically buckling-restrained braced frames
- 2020
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Ingår i: Journal of Applied Engineering Science. - : Centre for Evaluation in Education and Science. - 1451-4117 .- 1821-3197. ; 18:4, s. 591-600
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this paper is to evaluate the structural response of composite steel-concrete eccentrically buckling-restrained braced frames (BRBFs). The finite element (FE) software ABAQUS is employed to nonlinearly analyse the BRBFs. Comparing the modelling and experimental test results validates the FE modelling method of the BRBF. Three different strong earthquake records of Tabas, Northridge, and Chi-Chi are selected for the nonlinear dynamic analyses. A BRBF is then designed having a shear link. Afterwards, the designed BRBF is analysed under the selected earthquake records using the validated modelling method. The lateral displacements, base shears, and energy dissipations of the frame and shear link rotations are achieved from the analyses of the BRBF. The results are compared and discussed. The obtained BRBF results are also compared with their corresponding steel eccentrically braced frame (EBF) results. It is concluded that the BRBF can generally accomplish the improved structural response compared with the EBF under the earthquake records. Meanwhile, the BRBF has larger base shear capacity than the EBF. Moreover, the BRBF dissipates more energy than the EBF.
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| 5397. |
- Bahrami, Alireza, et al.
(författare)
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Evaluation of Untreated and Surface-Treated Wooden Facades of Buildings in Sweden
- 2023
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Ingår i: Coatings. - : MDPI. - 2079-6412. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- In this research, untreated and surface-treated wooden facades of buildings are investigated and compared with regard to durability, environmental impact, and cost using the document and literature studies supplemented with quantitative data. The investigation is based on the influence on the wood by external factors, either in its natural form or with a protective layer of a surface treatment. It is resulted from the study that from a durability viewpoint, it is not always advantageous to paint a wooden facade. Yakisugi, a thermal modification for wooden facades that involves burning the wood to create a protective surface layer, has shown better properties, which, in combination with a lower need for maintenance, can be considered the leading treatment for facades. From an environmental perspective, Yakisugi, like untreated wood, has demonstrated advantages compared with conventional paints. Paints often come with maintenance requirements that should be carried out correctly to avoid extensive costs. Cost is an important factor that can be decisive when users choose a surface treatment. What determines the cost is the relationship between durability and maintenance intervals. The need for the maintenance of paints leads to large financial costs during the working life of a wooden facade, which differs from Yakisugi or an untreated wooden facade that can be considered maintenance-free. In order to meet the growing environmental demands from a national level to a global scale, unconventional surface treatments for wooden facades should be promoted in the future.
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| 5398. |
- Bahrami, Alireza, et al.
(författare)
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Experimental Investigation of Ultimate Shear Force Capacity of Glulam Reinforced with Glued-in Threaded Rods
- 2023
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Ingår i: The Open Construction & Building Technology Journal. - : Bentham. - 1874-8368. ; 17, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Abstract:Background:Glued-in threaded (GIT) rods have been considered an effective timber connection method having several advantages, such as high load-carrying capacity, great stiffness, and good fire resistance. This type of connection has widely been utilized in newly built modern timber structures and for reinforcing the existing ones.Objective:The purpose of this experimental research is to investigate how the ultimate shear force capacity (USFC) of glulam is affected if it is reinforced with GIT rods and to study the interaction between the glulam and GIT rods. The results of this research can help researchers and engineers to select a suitable method of reinforcing the glulam with GIT rods at a superior inclination angle (IA) to the fiber direction in order to achieve higher USFCs.Methods and Experimental Tests:A total of forty glulam samples were tested for failure. The experimental tests consisted of five different series of samples with eight samples in each series. Sample series 1 were unreinforced glulam. Sample series 2 and 4 were glulam reinforced with the GIT rods at two different IAs of 45° and 90° to the fiber direction, respectively. Sample series 3 and 5 were glulam reinforced in the same way as sample series 2 and 4, but they were split in the middle. The samples were tested for failure using a standard testing machine. The machine was connected to a computer that recorded all the values obtained from the tests.Results:The results of the study were obtained as force-displacement graphs. The stiffness of the samples and interaction between the glulam and GIT rods were also calculated. The results achieved from the experimental tests of different series were compared and discussed.Conclusion:The experimental tests resulted in a 12.5% increase in the average USFC of sample series 2. However, the average USFC of sample series 4 was not enhanced significantly. The interaction between the glulam and GIT rods was obtained as 31.8% for the samples with reinforcing at the IA of 45° to the fiber direction and 3.8% for the samples with reinforcing at the IA of 90° to the fiber direction. Reinforcing the glulam with the GIT rods demonstrated the potential of enhancing its USFC. However, reinforcing the glulam with the GIT rods at the IA of 45° to the fiber direction was found to be superior to reinforcing the glulam with the GIT rods at the IA of 90° to the fiber direction.
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| 5399. |
- Bahrami, Alireza, et al.
(författare)
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Factors Influencing Choice of Wooden Frames for Construction of Multi-Story Buildings in Sweden
- 2023
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Ingår i: Buildings. - : MDPI. - 2075-5309. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Construction of buildings with wooden frames higher than two stories has been permitted in Sweden since 1994. As construction of multi-story buildings with wooden frames is relatively new, people in the construction industry are more likely to construct these buildings with concrete frames. The current research evaluates the factors influencing the choice of wooden frames for construction of multi-story buildings in Sweden. The purpose of this study is to explain which advantages and disadvantages construction companies in Sweden consider with wooden construction and to highlight the factors for why multi-story buildings are built with wood to a lesser extent than with other materials. The main goal is to investigate what factors or assumptions construction companies base their decisions on, and whether experience and competence in wooden frames for construction of multi-story buildings are considered in short supply in Sweden today. The chosen method for this research is a descriptive survey study with a qualitative and quantitative approach. The survey is based on respondents from five leading building companies in Sweden with regard to the companies’ revenue. The respondents had either previous experience in constructing multistory buildings with wooden frames, experienced respondents (ERs), or no experience, unexperienced respondents (UERs). 63% of the respondents were ERs, while 37% of them were UERs. It is resulted that the respondents think there is a lack of competence and experience in wooden frames for construction of multi-story buildings in Sweden. Factors that have the greatest impact on decisions to construct with wooden frames are positive environmental and climatic aspects as well as production advantages. Factors that are considered as major obstacles to construct with wooden frames are cost, acoustics, and moisture problems.
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| 5400. |
- Bahrami, Alireza, et al.
(författare)
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Finite element analysis of ultimate load capacity of slender concrete-filled steel composite columns
- 2011
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Ingår i: International Conference on Advanced Science, Engineering and Information Technology, Bangi-Putrajaya, Malaysia. - 9789834236649 ; , s. 576-581
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Konferensbidrag (refereegranskat)abstract
- Ultimate load capacity of slender concrete-filled steel composite columns is investigated in this paper. Nonlinear analyses are done by the use of finite element software, LUSAS, to study the ultimate axial load behaviour of the columns. Verification of the finite element modelling is done by comparing the result with the corresponding experimental result reported by other researchers. Analyses are carried out to assess different shapes and number of cold-formed steel sheeting stiffeners with various thicknesses of cold-formed steel sheets and their effects on the behaviour and ultimate axial load capacity of the columns. The results are presented in the form of axial load-normalized axial shortening plots. It is demonstrated that the ultimate axial load capacity of the slender concrete-filled steel composite columns can be accurately predicted by proposed finite element modelling. Obtained results from the study show that various thicknesses of cold-formed steel sheets, and different shapes and number of stiffeners influence the ultimate axial load capacity and behaviour of the columns. Also, the ultimate axial load capacity of the columns is improved by increase of number of stiffeners. Moreover, increase of thickness of cold-formed steel sheet enhances the ultimate axial load capacity.
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