• Structural Engineering and Mechanics
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• 제60권3호
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• pp.507-527
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• 2016

The use of shape memory alloys (SMAs) has been seriously considered in seismic engineering due to their capabilities, such as the ability to tolerate cyclic deformations and dissipate energy. Five 3-D extended end-plate connection models have been created, including one conventional connection and four connections with Nitinol bolts of four different prestress forces. Their cyclic behaviors have been investigated using the finite element method software ANSYS. Subsequently, the moment-rotation responses of the connections have been derived by subjecting them to cyclic loading based on SAC protocol. The results obtained in this research indicate that the conventional connections show residual deformations despite their high ductility and very good energy dissipation; therefore, they cannot be repaired after loading. However, while having good energy dissipation and high ductility, the connections equipped with Nitinol bolts have good recentering capability. Moreover, a connection with the mentioned specifications has been modeled, except that only the external bolts replaced with SMA bolts and assessed for seismic loading. The suggested connection shows high ductility, medium energy dissipation and very good recentering. The main objective of this research is to concentrate the deformations caused by cyclic loading on the connection in order to form super-elastic hinge in the connection by the deformations of the shape memory alloy bolts.

• Structural Engineering and Mechanics
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• 제24권3호
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• pp.307-321
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• 2006

This paper is concerned with the behaviour of steel and concrete composite joints subjected to reversal of loading. Three cruciform composite joint specimens and one bare steel joint specimen were tested so that one side of the beam-to-column connection was under negative moment and another side under positive moment. The steelwork beam-to-column connections were made of bolted end plate with an extended haunch section. Composite slabs employing metal decking were used for all the composite joint specimens. The moment-rotation relationships for the joints were obtained experimentally. Details of the experimental observations and results were reported.

• Steel and Composite Structures
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• 제48권5호
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• pp.547-564
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• 2023

This study investigates the effect of bolt preloading on the rotational stiffness of stainless steel end-plate connections. An experimental programme incorporating 11 full-scale joint specimens are carried out comparing the behaviours of fully pre-tensioned (PT) and snug-tightened (ST) flush/extended end-plate connections, made of austenitic or lean duplex stainless steels. It is observed from the tests that the presence of bolt preloading leads to a significant increase in the rotational stiffness. A parallel finite element analysis (FEA) validated against the test results demonstrates that the geometric imperfection of end-plate has a strong influence on the moment-rotation response of preloaded end-plate connections, which is crucial to explain the observed "two-stage" behaviour of these connections. Based on the data obtained from the tests and FE parametric study, the performance of the Eurocode 3 predictive model is evaluated, which exhibits a significant deviation in predicting the rotational stiffness of stainless steel end-plate connections. A modified bi-linear model, which incorporates three key properties, is therefore proposed to enable a better prediction. Finally, the effect of bolt preloading is demonstrated at the system (structure) level considering the serviceability of semi-continuous stainless steel beams with end-plate connections.

• 한국강구조학회 논문집
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• 제27권2호
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• pp.251-260
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• 2015

단부판 접합부는 다양한 형태로 보-기둥 모멘트 접합부에 적용되고 있다. 이러한 단부판 접합부는 단부판의 두께 및 길이, 고장력 볼트의 개수 및 직경, 고장력볼트의 게이지 거리, 고장력볼트의 지레작용력, 용접부의 치수 및 길이 등에 따라서 상이한 거동특성, 강성 및 강도, 에너지소산능력의 변화를 나타낸다. 따라서 이 연구는 단부판의 두께 변화에 따른 인장측에 체결된 고장력볼트의 지레작용력 및 축방향 인장강성을 파악하고, 단부판의 거동특성에 영향을 미치는 이러한 변수들을 예측하기 위한 해석모델을 제안하기 위하여 진행하였다. 이를 위하여 이 연구에서는 단부판의 두께만을 변수로 선택하여 비보강 확장단부판 접합부에 대한 3차원 비선형 유한요소해석을 수행하였다.

• Steel and Composite Structures
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• 제18권6호
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• pp.1423-1450
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• 2015

The paper presents the details and results of an experimental study on bolted end-plate joints of industrial type steel building frames. The investigated joints are commonly used in Lindab-Astron industrial buildings and are optimized for manufacturing, erection and durability. The aim of the research was to provide an experimental background for the design model development by studying load-bearing capacity of joints, bolt force distribution, and end-plate deformations. Because of the special joint details, (i.e., joints with four bolts in one bolt-row and HammerHead arrangements), the Eurocode 3 standardized component model had to be improved and extended. The experimental programme included six different end-plate and bolt arrangements and covered sixteen specimens. The steel grade of test specimens was S355, the bolt diameter M20, whereas the bolt grade was 8.8 and 10.9 for the two series. The end-plate thickness varied between 12 mm and 24 mm. The specimens were investigated under pure bending conditions using a four-point-bending test arrangement. In all tests the typical displacements and the bolt force distribution were measured. The end-plate plastic deformations were measured after the tests by an automatic measuring device. The measured data were presented and evaluated by the moment-bolt-row force and moment-distance from centre of compression diagrams and by the deformed end-plate surfaces. From the results the typical failure modes and the joint behaviour were specified and presented. Furthermore the influence of the end-plate thickness and the pretension of the bolts on the behaviour of bolted joints were analysed.

• Steel and Composite Structures
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• 제50권6호
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• pp.627-641
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• 2024

This paper presents an experimental and numerical study to investigate the behavior of the precast segmental concrete beams (PSCBs) utilizing high-strength concrete (HSC) connected in the zone of the maximum bending moment using steel extended endplate connections (EECs). The experimental study consisted of five beams as follows: The first beam was the control beam for comparison, which was an unconnected one-piece beam made of HSC. The other four other beams consisted of two identical pieces of precast concrete. An important point to be noted is that at the end of each piece, a steel plate was used with a thickness of 10 mm. Moreover, this steel plate was welded to the lower and upper reinforcing bars of the beam. Furthermore, the steel plate was made to connect the two pieces using the technique of EECs. Several variables were taken in these four beams, whether from the shape of the connection or enhancing the behavior of the connection using the post-tensioning technique. EECs without stiffeners were used for some of the tested beams. The behavior of these connections was improved using stiffeners and shear bolts. To get accurate results, a comparison was made between the behaviors of the five beams. Another important point to be noted is that Abaqus and SAP2000 programs were used to investigate the behavior of PSCBs and to ensure the accuracy of the modeling process which showed a good agreement with the experimental results. Additionally, the simplified modeling using SAP2000 was able to model the nonlinear behavior of PSCBs connected using steel EECs. It was found that the steel pre-tensioned bolted EECs, reinforced with steel stiffeners and shear anchors, could be used to connect the precast HSC segmental beams via the internal pre-stressing technique.

• Earthquakes and Structures
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• 제19권5호
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• pp.315-329
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• 2020

Through bolt connections in Concrete Filled Steel Tubes (CFSTs) has been proved to be good in terms of seismic performance and constructability. Stiffened extended end plate connection with full through type bolt helps to avoid field weld altogether, and hence to improve the quality of joints. An experimental study was conducted on the hysteretic performance of square interior beam-column connections using flat extended end plates with through bolt. The study focuses on the effect of the bond between the tie rod and the core concrete on the cyclic performance of the joint. The study also quantifies how much the interior joint is getting strengthened due to the confinement effect induced by bi-directional bolting, which is widely used in 3D moment resisting frames. For a better understanding of the mechanism and for the prediction of shear capacity of the panel zone, a mathematical model was generated. The various parameters included in the model are the influence of axial load, amount of prestress induced by bolt tightening, anchorage, and the concrete strut action. The study investigates the strength, stiffness, ductility, and energy dissipation characteristics. The results indicate that the seismic resistance is at par with American Institute of Steel Construction (AISC) seismic recommendations. The bidirectional bolting and bond effect have got remarkable influence on the performance of joints.

• Steel and Composite Structures
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• 제27권6호
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• pp.727-745
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• 2018

The design criteria and the corresponding performance levels characterize the response of extended stiffened end-plate beam-to-column joints. In order to guarantee a ductile behavior, hierarchy criteria should be adopted to enforce the plastic deformations in the ductile components of the joint. However, the effectiveness of thesecriteria can be impaired if the actual resistance of the end-plate material largely differs from the design value due to the potential activation of brittle failure modes of the bolt rows (e.g., occurrence of failure mode 3 in the place of mode 1 per bolt row). Also the number and the position of bolt rows directly affect the joint response. The presence of a bolt row in the center of the connection does not improve the strength of the joint under both gravity, wind and seismic loading, but it can modify the damage pattern of ductile connections, reducing the gap opening between the end-plate and the column face. On the other hand, the presence of a central bolt row can influence the capacity of the joint to resist the catenary actions developing under a column loss scenario, thus improving the joint robustness. Aiming at investigating the influence of these features on both the cyclic behavior and the response under column loss, a wide range of finite element analyses (FEAs) were performed and the main results are described and discussed in this paper.