| 1. |
- 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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| 2. |
- Bahrami, Alireza, et al.
(författare)
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Investigation of steel frames equipped with steel eccentric braces and steel-concrete buckling-restrained braces having moment link
- 2021
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Ingår i: Open Construction & Building Technology Journal. - : Bentham Science. - 1874-8368. ; 15, s. 55-69
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Tidskriftsartikel (refereegranskat)abstract
- Background: Different bracing systems of steel Eccentric Braces (EBs) and steel-concrete Buckling-Restrained Braces (BRBs) can be used in steel frames in order to make the frames stronger in resisting lateral loads. These steel frames with EBs or BRBs are generally called Eccentrically Braced Frames (EBFs) or Buckling-Restrained Braced Frames (BRBFs), respectively.Objective: This study aims to investigate steel frames with bracing systems of steel EBs and steel-concrete BRBs having moment link.Methods: The EBFs and BRBFs are nonlinearly analysed employing the finite element software ABAQUS. Experimental tests of the EBF and BRB are utilised for the validation of their modelling. The modelling is validated by comparing the modelling results with experimental tests results. Then, an EBF and a BRBF are designed having moment link. The extreme earthquake records of Tabas, Chi-Chi, and Northridge are selected for the dynamic analyses of the EBF and BRBF. The validated modelling method is applied to analyse the designed EBF and BRBF under the selected earthquake records.Results:The achieved results from the analyses are lateral displacements, base shears, and energy dissipations of the EBF and BRBF and moment linkrotations. These results are compared and discussed.Conclusion:It is concluded that the hierarchy of the lateral displacements of the analysed EBF and BRBF, having moment link, is related to the Tabas, Chi-Chi, and Northridge records because the lateral displacements of the frames are directly proportional to the peak ground accelerations of the records, and there is the same hierarchy for the records in terms of their peak ground accelerations. Lower lateral displacements are witnessed for the BRBF than the EBF subjected to the Tabas and Chi-Chi records. However, larger lateral displacement is observed for the BRBF than the EBF under the Northridge record. The same procedure as the lateral displacements is also revealed for the effectiveness of the BRBF with regard to its link rotations compared with the EBF. Moreover, the BRBF improves the base shear capacities and energy dissipations of the frame compared with the EBF. Consequently, the BRBF is generally demonstrated to be superior to the EBF from the structural performance point of view. Thus, the BRBF can be used more efficiently in structures subjected to large lateral loads compared with the EBF.
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| 3. |
- Bahrami, Alireza, et al.
(författare)
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Ultimate behaviour of perforated steel plate girders subjected to shear loading
- 2020
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Ingår i: Open Construction & Building Technology Journal. - : Bentham Open. - 1874-8368. ; 14, s. 70-83
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Tidskriftsartikel (refereegranskat)abstract
- Background:The Perforated Steel Plate Girders (PSPGs) are those Steel Plate Girders (SPGs) that have openings in their web. The PSPGs are significant structural members to withstand bending mainly. The proper combination of steel plates is applied to fabricate the PSPGs. When the available rolled steel profiles cannot carry the applied loads, the use of beams made of the steel plates is unavoidable.Objective:The present paper presents the ultimate behaviour of PSPGs subjected to shear loading.Methods:In order to carry out the study, the finite element method is used as a practical design tool for predicting the ultimate behaviour of the PSPGs under shear loading. Two experimentally tested PSPGs are selected to conduct the modelling accuracy using ABAQUS. All the features of the tested specimens are considered in the modelling. The finite element modelling results are compared with the experimental tests results, which verify the modelling. Since the accuracy of the modelling is demonstrated, thereafter, the method is used for the nonlinear analysis of the developed PSPGs having different circular and rectangular openings. Various parameters are adopted in the analysis to vastly evaluate their effects on the ultimate behaviour of the PSPGs. The parameters include shape of the openings (circular and rectangular openings), number of the openings (2 and 4 openings), arrangement of the openings (horizontal and vertical openings), using steel frame around the openings, utilising diagonal steel stiffeners to connect the steel frame to the corners of the PSPGs, and thicknesses (2 mm and 4 mm) of the steel frame and the diagonal steel stiffeners.Results:The obtained results from the nonlinear analysis of the PSPGs are summarised considering various parameters. The results are compared and discussed, taking into account the effects of the parameters on the ultimate behaviour of the PSPGs.Conclusion:The study highlights that the shape of the openings affects the behaviour of the PSPGs. Accordingly, circular openings are preferred compared with the rectangular ones. Also, as the number of the openings is increased, the ultimate capacity of the PSPGs is reduced. The behaviour of the PSPGs is considerably affected by the arrangement of the openings in which the horizontal openings have better performance than the vertical ones. If the steel frame and/or the steel stiffeners are utilised, the ultimate capacity is enhanced. The ultimate capacity of the PSPGs is improved by increasing the thickness of the steel frame and/or stiffeners. The failure modes of the PSPGs with circular and rectangular openings are indicated and evaluated.
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| 4. |
- Barve, Prasad, et al.
(författare)
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A Comprehensive Review on Effects of Material Composition, Mix Design, and Mixing Regimes on Rheology of 3D-Printed Geopolymer Concrete
- 2024
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Ingår i: Open Construction & Building Technology Journal. - : Bentham. - 1874-8368. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Recent years have witnessed a significant growth in the research and development of additive manufacturing methods involving concrete and cementitious materials, with technologies like three-dimensional (3D) printing becoming more widely used in the construction industry. Construction has the possibility to be revolutionized, not only in the context of cost savings but also in the context of increased sustainability and functionality. 3D printing of concrete is a cutting-edge technology that has the potential to speed up construction, reduce labor costs, give architects more creative freedom, improve precision, obviate requirements for formwork, and result in less construction wastes. In addition, 3D printing can be a long-term solution for both economy and environment. Even though 3D printing in concrete has made tremendous strides recently, developing an effective 3D-printable material that decreases material usage and enhances performance is critical for carbon dioxide reduction. Robust geopolymer formulations for 3D printing concrete technology in current construction applications have emerged as the subject of much research among scientists to find novel ways to circumvent this constraint. This study intends to highlight the current state of the art in developing 3D-Printed Geopolymer Concrete (3DPGC) with a comprehensive review related to the material composition, mix design, and mixing regimes on rheology of 3DPGC. The rheology of 3DPGC in terms of printability and buildability is discussed. The mixing regimes employed for the preparation of one-part and two-part 3DPGC are tabulated and commented on. Lastly, the research gaps are identified and summarized, and several research directions are also provided for future investigations to expedite the ubiquitous use of 3DPGC in versatile construction applications.
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| 5. |
- Koch, Christian, 1958, et al.
(författare)
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Learning from demonstration? Developing construction for sustainability
- 2014
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Ingår i: Open Construction and Building Technology Journal. - : Bentham Science Publishers Ltd.. - 1874-8368. ; 8:1, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- Demonstration projects are often used in the building sector to provide a basis for using new processes and/or products. The climate change agenda implies that construction is not only required to deliver value for the customer, cost reductions and efficiency but also sustainable buildings. This paper reports on an early demonstration project, the building of a passive house dormitory in the Central Region of Denmark in 2006-2009. The project was supposed to deliver value, lean design, prefabrication, quality in sustainability, certification according to German standards for passive houses, and micro combined heat and power using hydrogen. Using sociological and business economic theories of innovation, the paper discusses how early movers of innovation tend to obtain only partial success when demonstrating their products and often feel obstructed by minor details. The empirical work encompasses both an evaluation of the design and construction process as well as a post-occupancy evaluation. Process experiences include the use of a multidisciplinary competence group and performance measurement. The commencement of the project was enthusiastic, but it was forced into more traditional forms of control, driven by such challenges as complying with cost goals, the need to choose a German prefab supplier, and local contractors. Energy calculations, indoor climate, issues related to square meter requirements, and the hydrogen element became problematic. The aim to obtain passive house certification prevailed over realizing a good indoor climate, which included sufficient heating. Project management must be able to handle quantitative complexity where simple issues add up to major challenges. © Koch and Bertelsen; Licensee Bentham Open.
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| 6. |
- Nordwall, Ulf, 1966-, et al.
(författare)
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A quantitative approach for valuating architectural qualities
- 2011
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Ingår i: The Open Construction and Building Technology Journal. - : Bentham Open. - 1874-8368. ; 5, s. 105-112
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Tidskriftsartikel (refereegranskat)abstract
- Architectural qualities is often valuated based on a describable nature with a more personal interpretation, such as living space, size of ground plot, the number of sanitation rooms, or standard points according to the property taxation. Models with values of a more measurable qualitative nature, such monetary parameters,are less used. Within other research areas, for example the environmental and economic field, there are examples of well used qualitative models. One example is the Contingent Valuation (CV) model. It can be used to measure values in terms of willingness to pay on a hypothetic market. In this paper we introduce adirect quantitative approach for evaluating architectural qualities based on the theory of CV. The architectural qualities investigated are: the patina and mellowness of building components, usage flexibility within the apartment, and properties and characteristics of the surroundings.The method has been applied on a smaller case-study of 150 people living in cooperative and rented flats at Ålidhem, Ålidbacken and Östermalm in Umeå, Sweden. The case study was used merely to demonstrate and evaluate the methodology. The study indicated that the introduced three architectural values could be investigated with the used CV approach. It was found that the tenants had a measureable willingness to pay for those qualities. This supports a notion that valuations of architectural qualities are not entirely subjective and dependent on the individuals. Consequently the study supports the proposal to use qualitative measures to grade and compare such qualities.
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| 7. |
- Szentes, Henrik, et al.
(författare)
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Societal changes and new conditions for the management of large construction projects
- 2013
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Ingår i: Open Construction & Building Technology Journal. - : Bentham Science Publishers Ltd.. - 1874-8368. ; 7, s. 182-192
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Tidskriftsartikel (refereegranskat)abstract
- The construction industry is often described as mature, conservative and resistant to change in research studies, governmental reports as well as in media. Both scholars and policy makers thereby find it critical to encourage innovation, development, and change within the construction industry. This study takes on a different perspective by investigating changes that have actually taken place. The aim is to increase the understanding of both backgrounds of changes which occurred, as well as how the changes have entailed new conditions for the management of large construction projects in Sweden. People working as clients' project manager, contractors' project manager or design manager were interviewed to obtain their perceived views on changes influencing the execution of large construction projects. Substantial changes have taken place creating new conditions for the management of large construction projects and a better understanding of these new conditions is important when planning for new projects. Changes within the field are often reactions to societal changes, and thus often implemented in an uncoordinated way creating sub-optimization and problems for the personnel. It seems as if the reputation of the construction industry being conservative has become an institution it-self amongst many professionals within the industry, potentially creating a self-fulfilling prophecy
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