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Mohammad Reza Adlparvar,Mohammad Ghasem Vetr,Farshad Ghaffari 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.1
It is commonly believed by structural engineering researchers that the slotted-web beam connection rectifies many common weaknesses, and hence this connection is recommended whenever possible. Suitable ductility without considerable strength loss is the most important advantage of this type of special moment connection. The shear force present in beam flanges with lateral torsional buckling are mentioned as the main causes of weld fracture in most connections. The separation of flange from beam’s web results in separation of the force shares of beam’s flange and web; also, removal of the shear from beam’s flanges will cause uniform distribution of stress through the width of the beam flange. In this study the seismic behavior of improved slotted-web beam connections is compared with similar samples numerically and experimentally. Results suggest that in case of proper use of beam flange stiffeners, this type of connection does not show any loss of strength and provides suitable ductility. Since shear strength of the panel zone is effective on beam-to-column weld strains, participation of the panel zone in seismic behavior of this type of connection is of interest. Results show that high participation of panel zone effect causes the possibility of weld fracture in beam web to increase and the maximum strength of the connection to decrease. Performance comparisons are made based on envelope curves and percentage of energy dissipation of the specimens. Suitable ductility at this connection proves that this connection shall be classified as special moment connection.
Belarbi, Abdeldjelil,Prakash, Suriya,You, Young-Min Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.2
This paper investigates the behavior of reinforced concrete (RC) circular columns under combined loading including torsion. The main variables considered in this study are the ratio of torsional moment to bending moment (T/M) and the level of detailing for moderate and high seismicity (low and high transverse reinforcement/spiral ratio). This paper presents the results of tests on seven columns subjected to cyclic bending and shear, cyclic torsion, and various levels of combined cyclic bending, shear, and torsion. Columns under combined loading were tested at T/M ratios of 0.2 and 0.4. These columns were reinforced with two spiral reinforcement ratios of 0.73% and 1.32%. Similarly, the columns subjected to pure torsion were tested with two spiral reinforcement ratios of 0.73% and 1.32%. This study examined the significance of proper detailing, and spiral reinforcement ratio and its effect on the torsional resistance under combined loading. The test results demonstrate that both the flexural and torsional capacities are decreased due to the effect of combined loading. Furthermore, they show a significant change in the failure mode and deformation characteristics depending on the spiral reinforcement ratio. The increase in spiral reinforcement ratio also led to significant improvement in strength and ductility.
Abdeldjelil Belarbi,Suriya Prakash,Young-Min You 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.2
This paper investigates the behavior of reinforced concrete (RC) circular columns under combined loading including torsion. The main variables considered in this study are the ratio of torsional moment to bending moment (T/M) and the level of detailing for moderate and high seismicity (low and high transverse reinforcement/spiral ratio). This paper presents the results of tests on seven columns subjected to cyclic bending and shear, cyclic torsion, and various levels of combined cyclic bending, shear, and torsion. Columns under combined loading were tested at T/M ratios of 0.2 and 0.4. These columns were reinforced with two spiral reinforcement ratios of 0.73% and 1.32%. Similarly, the columns subjected to pure torsion were tested with two spiral reinforcement ratios of 0.73% and 1.32%. This study examined the significance of proper detailing, and spiral reinforcement ratio and its effect on the torsional resistance under combined loading. The test results demonstrate that both the flexural and torsional capacities are decreased due to the effect of combined loading. Furthermore, they show a significant change in the failure mode and deformation characteristics depending on the spiral reinforcement ratio. The increase in spiral reinforcement ratio also led to significant improvement in strength and ductility.
복합하중 시 단조 및 반복 비틀림을 받는 RC 부재의 비틀림 거동
이가영 ( Lee Ga-yeong ),전재성 ( Jeon Jae-seong ),김동환 ( Kim Dong-hwan ),김형국 ( Kim Hyeong-gook ),김길희 ( Kim Kil-hee ) 한국구조물진단유지관리공학회 2022 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.26 No.2
이 연구에서는 가력 방법을 변수로 단조가력 및 반복가력 시 축력, 휨, 전단, 비틀림에 의한 복합하중을 받는 RC 부재의 거동을 비교·평가하였다. 실험결과, 단조와 반복가력 시 최대 비틀림내력(T<sub>n</sub>)은 유사한 반면, 반복가력에 대한 최대 비틀림내력 시 비틀림 회전각(θ<sub>n</sub>) 및 비틀림 연성(μ<sub>T</sub>)은 단조가력에 비해 각각 30%, 36% 감소하였다. 복합하중을 받는 RC 부재의 비틀림 설계에 있어 지진 시 부재의 동적 거동에 의한 비틀림내력 및 연성의 감소가 고려되어야 할 것으로 판단된다.
The torsional behavior of reinforced self-compacting concrete beams
Aydin, Abdulkadir C.,Bayrak, Baris Techno-Press 2019 Advances in concrete construction Vol.8 No.3
Torsional behaviors of beams are investigated for the web reinforcement and the concrete type. Eight beams with self-compacting concrete (SCC) and twelve beams with conventional concrete (CC) were manufactured and tested. All the models manufactured as the $250{\times}300{\times}1500mm$ were tested according to relevant standards. Two concrete types, CC and SCC were designed for 20 and 40 MPa compressive strength. From the point of web reinforcement, the web spacing was chosen as 80 and 100 mm. The rotation angles of the concrete beams subjected to pure torsional moment as well as the cracks occurring in the beams, the ultimate and critical torsional moments were observed. Moreover, the ultimate torsional moments obtained experimentally were compared with the values evaluated theoretically according to some relevant standards and theories. The closest estimations were observed for the skew-bending theory and the Australian Standard.
Failure analysis of tubes under multiaxial proportional and non-proportional loading paths
Mohammad Hossein Iji,Ali Nayebi 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.2
The failure of a thin-walled tube was studied in this paper based on three failure models. Both proportional and nonproportional loading paths were applied. Proportional loading consisted of combined tension-torsion. Cyclic non-proportional loading was also applied. It was a circular out-of-phase axial-shear stress loading path. The third loading path was a combination of a constant internal pressure and a bending moment. The failure models under study were equivalent plastic strain, modified Mohr-Coulomb (Bai-Wierzbicki) and Tearing parameter models. The elasto-plastic analysis was conducted using J2 criterion and nonlinear kinematic hardening. The return mapping algorithm was employed to numerically solve the plastic flow relations. The effects of the hydrostatic stress on the plastic flow and the stress triaxiality parameter on the failure were discussed. Each failure model under study was utilized to predict failure. The failure loads obtained from each model were compared with each other. The equivalent plastic strain model was independent from the stress triaxiality parameter, and it predicted the highest failure load in the bending problem. The modified Mohr-Coulomb failure model predicted the lowest failure load for the range of the stress triaxiality parameter and Lode’s angle.
이성희,최성모,E.T. Lee,Hyun Ju Shim 국제구조공학회 2008 Steel and Composite Structures, An International J Vol.8 No.5
In December 2005, one(A) of the two pre-engineered warehouse buildings in the port of K City of Korea was completely destroyed and the other(B) was seriously damaged to be demolished. Over-loaded snow and unexpected blast of wind were the causes of the accident and destructive behavior was brittle fracture caused by web local buckling and lateral torsional buckling at the flange below rafter. However, the architectural design technology of today based on material non-linear method does not consider the tolerances to solve the problem of such brittle fracture. So, geometric non-linear evaluation which includes initial deformation, width-thickness ratio, web stiffener and unbraced length is required. This study evaluates the structural safety of 4 models in terms of width-thickness ratio and unbraced length using ANSYS 9.0 with parameters such as width-thickness ratio of web, existence/non-existence of stiffener and unbraced length. The purpose of this study is to analyze destructive mechanism of the above-mentioned two warehouse buildings and to provide ways to promote the safety of pre-engineered buildings.
Ultimate strength of long-span buildings with P.E.B (Pre-Engineered Building) system
이성휘,최성모,김영호 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.19 No.6
With the improvement of the quality of construction materials and the development of construction technologies, large-scale long-span steel frame buildings have been built recently. The P.E.B system using tapered members is being employed as an economically-efficient long-span structure owing to its advantage of being able to distribute stress appropriately depending on the size of sectional areas of members. However, in December 2005 and in February 2014, P.E.B buildings collapsed due to sudden loads such as snow loads and wind gusts. In this study, the design and construction of the P.E.B system in Korea were analyzed and its structural safety was evaluated using the finite element analysis program to suggest how to improve the P.E.B system in order to promote the efficient and rational application of the system.