Compression test of RCFT columns with thin-walledsteel tube and high strength concrete

Alifujiang Xiamuxi,Akira Hasegawa 국제구조공학회 2011 Steel and Composite Structures, An International J Vol.11 No.5

It is clear from the former researches on reinforced concrete filled steel tubular (RCFT) structuresthat RCFT structures have higher strength and deformation capacity than concrete filled steel tubular (CFT) structures. However, in the case of actual applications to large-scaled structures, the thin-walled steel tube must be used from the view point of economic condition. Therefore, in this study, compression tests of RCFT columns which were made by thin-walled steel tube or small load-sharing ratio in cooperation with high strength concrete were carried out, meanwhile corresponding tests of CFT, reinforced concrete (RC), pure concrete and steel tube columns were done to compare with RCFT. By the a series of comparison and analysis, characteristics of RCFT columns were clarified, and following conclusions were drawn: RCFT structures can effectively avoided from brittle failure by the using of reinforcement while CFT structures are damaged due to the brittle failure; with RCFT structures, excellent bearing capacity can be achieved in plastic zone by combining the thin-walled steel tube with high strength concrete and reinforcement. The smaller load-sharing ratio can made the reinforcement play full role; Combination of thin-walled steel tube with high strength concrete and reinforcement is effective way to construct large-scaled structures.

Recent Research Advances of High Strength Steel Structures and Codification of Design Specification in China

Gang Shi,Fangxin Hu,Yong-Jiu Shi 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.4

High strength steel (HSS) with the nominal yield strength fy≥460 MPa has been applied in numerous modern building andbridge structures all over the world. Steel structures using high strength steel have obvious advantages in structural,architectural, economical, environment protection and energy saving aspects. After a brief introduction of early studies, recentresearch advances of high strength steel structures in Tsinghua University in China are comprehensively reviewed. Systematicinvestigations have been carried out on static- and cyclic-loading behavior of high strength steels and their welded connections,residual stress of high strength steel hot-rolled and welded sections, overall and local buckling behavior of high strength steelcolumns under axial compression, seismic behavior of high strength steel columns under combined bending and compression,bearing and slip resistance of bolted connections with high strength steel slices. The research results show that mechanicalbehavior of high strength steel structures has been improved much compared with ordinary strength steel structures, so thedesign methods in current design codes or specifications need be updated to be applicable to high strength steel structures. Therefore, as the chief-editor institute, Tsinghua University has organized 34 institutes including universities, design andresearch institutes, steel structure fabricators, and steel manufacturers, to codify a new code, i.e. Design Specification of HighStrength Steel Structures in China. Based on the above research results, new design methods and calculation formulaeapplicable to high strength steel structures are incorporated into this design specification. The outline of this specification isdiscussed in detail in this paper.

Seismic retrofit of framed structures using a steel frame assembly

Michael Adane,Seungho Chun,Jinkoo Kim 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.6

This study aimed to develop a seismic retrofit technique using a steel frame which can be easily transported and assembled on site. This enables the retrofit steel frame to be easily attached to an existing structure minimizing the unwanted gap between the structure and the steel frame assembly. A one-story one-bay RC frame was tested with and without seismic retrofit using the proposed steel frame to verify the seismic retrofit effect of the proposed system, and an analysis model was developed in Opensees for seismic performance evaluation of a case study soft first-story model structure retrofitted with the developed steel frame assembly. Seismic performance of the model structure was also evaluated considering soil structure interaction effect. The experimental study confirmed that the proposed seismic retrofit system can be applied effectively to improve the seismic performance of framed structures. Time history analysis results of the model structure showed that the proposed steel frame assembly was effective in increasing the seismic load resisting capacity of the soft first-story structure. However more steel frame assemblies were required to satisfy the given performance limit state of the model structure located on weak soil due to the negative soil-structure interaction effect.

A Comparative Analysis of Competitiveness in the Steel Industry : The Case of China and Korea

Seung-Taek Lee,Yuri Yoon 한국무역연구원 2014 貿易 硏究 Vol.10 No.2

Hand in hand with China's growing economy, its steel industry also continues to exhibit remarkable growth. In particular, Korea's steel import from China has rapidly increased owing to China's oversupply caused by expansion of its steel facilities. Many experts are aware of this situation and suggest that the Korean steel industry has encountered the challenge of a fast-growing Chinese steel industry, and that many of China's steel products including long products, flat products, pipes and tubes, have been converted to competitive advantages, from competitive inferior. Meanwhile in Korea, delayed investment in a blast furnace facility despite escalating steel demand extensive users of steel: automobile, shipbuilding, and electronics sectors, has triggered a supply-demand imbalance in the country. Thus, a hike in steel imports from China is seen to cause this structural supply-demand imbalance in Korea's steel industry. Ever since Hyundai Steel's production expansion involving blast furnace facilities, there is need for the industry to concentrate on developing new markets for its facilities' output in Korea. Therefore, Korea's steel industry desperately needs efficient distribution management, as well as export promotion strategy through its global trading network to effectively address its structural supply-demand imbalances.

Bending performance of NSTS members based on steel tube connection

Xueliang Zhang,Lianguang Wang,Bailing Chen,Yaosheng Zhang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.1

This paper proposes a NSTS (new steel tube slab) structure by connecting the longitudinal steel tubes with small steel tubes in transverse, in order to decrease the construction difficulty and improve the bearing capacity of existing NTR (new tubular roof) or STS (steel tube slab) structures. Experimental study on the bending performance and influences of following parameters are carried out: the connection type of the steel tube, the diameter and eccentricity of the small steel tube, and the thickness of the bottom steel plate. The results show that the NSTS members present progressive ductile flexural failure under concentrated load. The connection type has important effect on the mechanical behavior, and the bolts fixed T-shaped plate (B+T) connection method, which provides much higher bending stiffness, is proved to be the most reliable connection type. The increase of small steel tube diameter enhances the bending performance as expected, which also confirms the effectiveness of the B+T connection, while the tube eccentricity presents little impact on the bearing capacity. The bottom steel plate significantly improves the bearing capacity and stiffness and reduces the mid-span deflection. Furthermore, the bending capacity calculation method is proposed and the calculated values show good agreement with the test results. Also, the effect rules of the diameter-thickness ratio of the small tube, the length-diameter ratio of the member and the thickness variety of the bottom steel plate on the bending capacity of NSTS members are further investigated based on the proposed theoretical method.

Development of High-Strength (780 N/mm2) Steel for Building Systems

Yuzuru Yoshida,Tadashi Obinata,Masaru Nishio,Toyoaki Shiwaku 한국강구조학회 2009 International Journal of Steel Structures Vol.9 No.4

The national project, initiated by the Comprehensive Scientific Technology Conference in the Cabinet Office, entitled “Development of New Structural systems Using Innovative Structural Materials” has two objectives: The first objective is to develop and produce new innovative steel materials. The second is to develop a new structural system using the new steel. This paper describes the production specification and the chemical composition. The required mechanical properties and test results conducted on the new steel that is produced are also presented. The national project, initiated by the Comprehensive Scientific Technology Conference in the Cabinet Office, entitled “Development of New Structural systems Using Innovative Structural Materials” has two objectives: The first objective is to develop and produce new innovative steel materials. The second is to develop a new structural system using the new steel. This paper describes the production specification and the chemical composition. The required mechanical properties and test results conducted on the new steel that is produced are also presented.

Numerical analysis of stainless steel-concrete composite beam-to-column joints with bolted flush endplates

Yuchen Song,Brian Uy,Jia Wang 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.1

A number of desirable characteristics concerning excellent durability, aesthetics, recyclability, high ductility and fire resistance have made stainless steel a preferred option in engineering practice. However, the relatively high initial cost has greatly restricted the application of stainless steel as a major structural material in general construction. This drawback can be partially overcome by introducing composite stainless steel-concrete structures, which provides a cost-efficient and sustainable solution for future stainless steel construction. This paper presents a preliminary numerical study on stainless steel-concrete composite beam-to-column joints with bolted flush endplates. In order to ensure a consistent corrosion resistance within the whole structural system, all structural steel components were designed with austenitic stainless steel, including beams, columns, endplates, bolts, reinforcing bars and shear connectors. A finite element model was developed using ABAQUS software for composite beam-to-column joints under monotonic and symmetric hogging moments, while validation was performed based on independent test results. A parametric study was subsequently conducted to investigate the effects of several critical factors on the behaviour of composite stainless steel joints. Finally, comparisons were made between the numerical results and the predictions by current design codes regarding the plastic moment capacity and the rotational stiffness of the joints. It was concluded that the present codes of practice generally overestimate the rotational stiffness and underestimate the plastic moment resistance of stainless steel-concrete composite joints.

Assessment of steel structures designed for progressive collapse under localized fires

Behrouz Behnam 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.2

Structural design against the progressive collapse has been a vital necessity for decades due to occasional tragic events. The question of whether designed structures against the progressive collapse are still robust if subjected to multi-hazard scenarios containing column removal and successive localized fires is ad-dressed in the current study. Two seven-story steel structures with an identical area but different structural configurations of 4- and 5-bays are designed against the progressive collapse; the structural components are also fireproofed for a 60 min fire resistance. The structures are then subjected to different column re-moval scenarios over different stories followed immediately by localized fires. Results indicate that the structures are not able to keep their stability under all of the considered scenarios; the 4-bay structure is more vulnerable than the 5-bay structure. It is also indicated that upper stories are more sensitive toward the considered scenarios than lower stories. To advance structural safety, two strategies are adopted: in-creasing the thickness of the insulation materials to reduce the thermal effects, or, increasing the safety fac-tor (ΩN) of the structures when designing against the progressive collapse. As for the first strategy, provid-ing a 35% and a 25% increase in the insulation thicknesses of the structural components of the 4-bay and 5-bay structures, respectively, can prevent a progressive collapse to trigger. As for the second strategy, in-creasing ΩN by 10% can enhance the structural integrity to where no collapse occurs under all of the sce-narios.

Consequence-based robustness assessment of a steel truss bridge

Pierluigi Olmati,Konstantinos Gkoumas,Francesca Brando,Liling Cao 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.4

Aim of this paper is to apply to a steel truss bridge a methodology that takes into account the consequences of extreme loads on structures, focusing on the influence that the loss of primary elements has on the structural load bearing capacity. In this context, the topic of structural robustness, intended as the capacity of a structure to withstand damages without suffering disproportionate response to the triggering causes while maintaining an assigned level of performance, becomes relevant. In the first part of this study, a brief literature review of the topics of structural robustness, collapse resistance and progressive collapse takes place, focusing on steel structures. In the second part, a procedure for the evaluation of the structural response and robustness of skeletal structures under impact loads is presented and tested in simple structures. Following that, an application focuses on a case study bridge, the extensively studied I-35W Minneapolis steel truss bridge. The bridge, which had a structural design particularly sensitive to extreme loads, recently collapsed for a series of other reasons, in part still under investigation. The applied method aims, in addition to the robustness assessment, at increasing the collapse resistance of the structure by testing alternative designs.

Sensors, smart structures technology and steel structures

Liu, Shih-Chi Techno-Press 2008 Smart Structures and Systems, An International Jou Vol.4 No.5

This paper deals with civil infrastructures in general, sensor and smart structure technology, and smart steel structures in particular. Smart structures technology, an integrated engineering field comprising sensor technology, structural control, smart materials and structural health monitoring, could dramatically transform and revolutionize the design, construction and maintenance of civil engineering structures. The central core of this technology is sensor and sensor networks that provide the essential data input in real time for condition assessment and decision making. Sensors and robust monitoring algorithms that can reliably detect the occurrence, location, and severity of damages such as crack and corrosion in steel structures will lead to increased levels of safety for civil infrastructure, and may significantly cut maintenance or repair cost through early detection. The emphasis of this paper is on sensor technology with a potential use in steel structures.