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RISS 인기검색어
- 검색키워드
- 저자 : Mehrzad Tahamouli Roudsari (검색결과 5 건)
- 무료
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Random imperfection effect on reliability of space structures with different supports
Mehrzad Tahamouli Roudsari,Mehrdad Gordini 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.3
The existence of initial imperfections in manufacturing or assembly of double-layer space structures having hundreds or thousands of members is inevitable. Many of the imperfections, such as the initial curvature of the members and residual stresses in members, are all random in nature. In this paper, the probabilistic effect of initial curvature imperfections in the load bearing capacity of double-layer grid space structures with different types of supports have been investigated. First, for the initial curvature imperfection of each member, a random number is generated from a gamma distribution. Then, by employing the same probabilistic model, the imperfections are randomly distributed amongst the members of the structure. Afterwards, the collapse behavior and the ultimate bearing capacity of the structure are determined by using nonlinear push down analysis and this procedure is frequently repeated. Ultimately, based on the maximum values of bearing capacity acquired from the analysis of different samples, structure’s reliability is obtained by using Monte Carlo simulation method. The results show the sensitivity of the collapse behavior of double-layer grid space structures to the random distribution of initial imperfections and supports type.
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Mehrzad Tahamouli Roudsari,Shohreh Sohaei,Morteza Torkaman,Seyed Ali Safaee,Salar Tahmasebi,Saleh Mohammadi,Mohammad Mehdi Ghiasvand 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.2
Connections play an important role in the response of steel moment resisting frames to seismic loading. Prequalified rigid connections are applicable to I-shaped or box columns. In I-shape beam to concrete-filled tube (CFT) column connections, continuity and doubler plates cannot be added to the column. Various details have been proposed to address this issue, many of which are not constructionally convenient to implement. The aim of this study is to present a simple and suitable detailing for I-shape beam to concrete-filled tube column connections. To that end, six full-scale experimental samples were built and subjected to cyclic quasi-static loading. In the samples, stiffened and un-stiffened channel links were used to connect the beam to the column. In each sample, the stiffeners were installed on a different position on the channel link. The results showed that compared to the connection in which the beam is directly connected to the column, using the stiffened channel link with stiffeners along the beam’s flange increases the strength and ductility of the connection by 12% and 72%, respectively. Considering their desirable performance and easy implementation, these connections can be considered as a suitable detailing for I-shape beam to CFT column connections in seismic regions.
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Shohreh Sohaei,Mehrzad Tahamouli Roudsari,Parham Memarzadeh 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.6
Circular columns are increasingly being used in today’s construction industry. Proper construction beam-circular column connections are an important problem in steel moment resisting frames with this type of connection. TahamouliRoudsari et al. introduced a new I-shaped beam-circular concrete-fi lled column connection in 2020. This connection makes use of a strengthened U-shaped profi le as an external stiff ener with simple detailing. Experimental tests showed that the connection satisfi es code-specifi ed criteria for rigid connections. The main objective of the present work is to present design guidelines and a more accurate numerical investigation of the detailing introduced by TahamouliRoudsari et al. For this, in the fi rst step, a numerical model of the experimental specimen was constructed and verifi ed in the ABAQUS fi nite element software. Then, through multiple nonlinear fi nite element analyses, it has been demonstrated that this type of connection can meet all the requirements of special moment resisting frames with rigid connections. The minimum thickness for the strengthened U-shaped profi le has been determined in such a way so that the plastic hinge could be created in the beam and the connection would have suffi cient stiff ness to be categorized as fully restrained. The eff ects of the geometry of the stiff ened channel link and the column-to-beam section modulus ratio on the behavior of the connection were investigated and a relationship has been developed to calculate the thickness of the stiff ened channel profi le. Also, evaluating the eff ects of axial loading in the column showed that the thickness of the U-shaped profi le and the stiff eners have no bearing on the axial load applied to the column.
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Introducing new rigid I-beam to box column connections by using a stiffened channel link
Allah Reza Moradi Garoosi,Mehrzad Tahamouli Roudsari,Morteza Torkaman,Shahab Bonyadirad,Ali Saeedmanesh,Khalil soleimani,Hosein Reza Lotfi,Roya Jowkar,Ali Alipour 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.4
The aim of this study is to present a new and suitable connection for I-shaped beams and box columns that is both constructionally convenient to implement and reliable in terms of its performance. Six full-scale experimental samples were constructed and subjected to cyclic Quasi-static loading. The first sample included an I-shaped beam which was directly connected to a box column, the second sample incorporated a channel link, and stiffened channel links were used in the remaining four samples. The results show that compared to the direct connection, using the stiffened channel link significantly improves the performance of the connection and increases its ultimate strength and ductility by 58% and 70%, respectively. Also, these connections satisfy the code-specified criteria for special moment resisting frames. They are therefore a suitable detail for rigid I-shaped-beam-to-box-column connections in seismically active regions.
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Experimental and numerical evaluation of rigid connection with reduced depth section
Allah Reza Moradi Garoosi,Mehrzad Tahamouli Roudsari,Behrokh Hosseini Hashemi 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.6
After medium or strong earthquakes, damage in the reduced portion of RBS connections occurs due to plastic deformations. The purpose of this paper is to numerically and experimentally investigate the reduced depth section connection as a replaceable fuse. In this regard, three commonly used rigid connections with RBS, a replaceable fuse with RBS, and a replaceable fuse with Reduced Depth Section (RDS-F) were evaluated. All specimens were subjected to quasi-static cyclic load until failure. Although the final strength of the RDS-F is lower than that of the other two, laboratory results showed that it had the maximum ductility among the three samples. The numerical models of all three laboratory samples were constructed in ABAQUS, and the results were verified with great accuracy. The results of more than 28 numerical analyses showed that the RDS-F sample is more ductile than the other specimens. Moreover, the thickness of the web and the plastic section modulus increasing, the final strength would be equal to the other specimens. Therefore, the modified RDS-F with replaceability after an earthquake can be a better alternative for RBS connections.
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