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.

강섬유 혼입 순환골재 콘크리트의 구조적 특성에 관한 연구

김정섭,신용석,박영배,김정훈,조창호 한국건축시공학회 2008 한국건축시공학회지 Vol.8 No.5

In this study, a sample was fabricated according to the recycled aggregate replacement level(0%, 30%, 60%), and the steel fiber mixing status in order to use a recycled aggregate as a concrete alternative coarse aggregate, and then the materials and structural characteristics of recycled aggregate and steel fiber which impacted the reinforced concrete were analyzed. A conclusion was derived as follows. After considering the results of various material experiments and mock-up test, when a flexural strength and a ductility factor is increased and the replacement level is increased through mixing the steel fiber with the recycled aggregate concrete, the ductility and flexural strength reduction seems to be inhibited by adding the steel fiber. Also, it is indicated that the recycled aggregate has almost-similar compressive strength, tensile strength, flexural strength and ductility capacity to the concrete which using the general gone even though the steel fiber is used and the replacement level is increased to 30%. Accordingly, the reinforced concrete frame using the steel fiber mixture and recycled aggregate seems to apply to the actual structure. In this study, a sample was fabricated according to the recycled aggregate replacement level(0%, 30%, 60%), and the steel fiber mixing status in order to use a recycled aggregate as a concrete alternative coarse aggregate, and then the materials and structural characteristics of recycled aggregate and steel fiber which impacted the reinforced concrete were analyzed. A conclusion was derived as follows. After considering the results of various material experiments and mock-up test, when a flexural strength and a ductility factor is increased and the replacement level is increased through mixing the steel fiber with the recycled aggregate concrete, the ductility and flexural strength reduction seems to be inhibited by adding the steel fiber. Also, it is indicated that the recycled aggregate has almost-similar compressive strength, tensile strength, flexural strength and ductility capacity to the concrete which using the general gone even though the steel fiber is used and the replacement level is increased to 30%. Accordingly, the reinforced concrete frame using the steel fiber mixture and recycled aggregate seems to apply to the actual structure.

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.

Research on cold-formed steel connections: A state-of-the-art review

Ying Qin,Zhi-Hua Chen 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.1

Cold-formed steel structures are increasingly attractive due to their benefits of good mechanical performance and constructional advantages. However, this type of construction is still not fully exploited as a result of the acknowledged difficulties involved in forming construction-efficient and cost-effective connections. Furthermore, there is a lack of information on the structural behavior of the cold-formed steel connections. In this study, the research on various cold-formed steel connections was comprehensively reviewed from both fundamental and structural points of view, based on the available experimental and analytical data. It reveals that the current design codes and guidelines for cold-formed steel connections tend to focus more on the individual bearing capacity of the fasteners rather than the overall structural behavior of the connections. Significant future work remains to be conducted on the structural performance of cold-formed steel connection. In addition, extensive previous research has been carried out to propose and evaluate an economical and efficient connection system that is obtained from the conventional connecting techniques used in the hot-rolled industry. These connecting techniques may not be suitable, however, as they have been adopted from hot-rolled steel portal frames due to the thinness of the sheet in cold-formed steels. The review demonstrates that with the increasing demand for cold-formed steel constructions throughout the world, it is crucial to develop an efficient connection system that can be prefabricated and easily assembled on site.

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.

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.

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.

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.

부식과 악취가스 대기확산 방지를 위한 액비저장조 밀폐형 지붕모델 개발

윤남규,이성현,김경원,염성현,Yun, N.K.,Lee, S.H.,Kim, K.W.,Yum, S.H. 한국축산환경학회 2008 축산시설환경학회지 Vol.14 No.1

악취가스의 대기확산을 방지하고, 액비의 발효를 위한 폭기장치의 가동을 정상화하여 액비저장조의 활용도를 높이고, 내식성 자재를 사용하여 구조적 안전성을 개선하기 위한 목적으로 액비저장조 밀폐형 지붕구조 모델을 개발하였으며, 결과를 요약하면 다음과 같다. 1. 액비저장조 및 지붕구조의 이용실태 조사결과, 악취가스의 발생으로 인한 민원 때문에 폭기장치 가동을 중단하고 있거나 특정시기에 한해 가동하는 농가가 대부분이었으며, 일반구조용 아연도금강관을 사용한 지붕 구조재의 부식이 다른 시설보다 빠르게 진행되고 있음을 확인하였다. 2. 구조자재의 강도시험 결과, 5년 동안 사용한 밀폐형 지붕 구조재의 경우 초기 강도의 34%까지 강도가 감소되는 등 부식에 의한 구조물의 강도저하가 심각하였으며, 내식성자재로 선발된 스테인리스(STS439)강의 경우 일반구조용강에 비해 1.4배 높은 강도를 나타내었다. 3. 직경 9.5m인 원형 액비저장조에 대하여 기존의 자재를 사용한 지붕모델과 내식성 자재를 사용한 지붕모델에 대하여 적설에 대한 구조안전성 분석 결과, 기존 자재를 사용한 경우에 비해 동일한 단면크기를 갖는 내식성 자재를 사용한 경우 적설에 대한 안전성이 약 2.3배까지 향상된 것으로 나타났다. 이상과 같이 본 연구에서 개발된 액비저장조 지붕모델은 밀폐형이므로 폭기시 발생하는 악취가스가 대기중으로 확산되지 않으며, 그 골조를 내식성이 우수한 스테인리스강, 아연용융도금강, FRP수지피복강을 사용하여 내구년한을 증가시킴으로써 구조적 안정성이 크게 향상되었다. 단, 금속재료의 부식에 대한 문제는 좀 더 장기간의 관찰과 실험을 통해 액비저장조 및 축산시설 고유의 부식속도를 구명하는 연구가 필요한 것으로 판단된다. The roof structural model of liquid manure storage tank was designed to improve a structural safety and an ability of resistance to corrosion by the bad environmental condition with high humidity and high gas concentration. Due to corrosion of a general steel, the 5 years used materials were reduced to one-third of a new material in the result of a bending strength test. Some structural materials were tested to evaluate a strength and an anti-corrosion, and stainless steel pipe (STS439), steel angle with zinc hot dipping, rectangular steel pipe covered with FRP (Fiberglass Reinforced Plastics) resin were selected finally. A stainless steel is more expansive about $3{\sim}5$ times than general structural steel. But its durability under heavy corrosive environment is expected twice as long as general steel. The roof models were designed as closed cone type for each of the three structural materials. In the result of a FEM (Finite Element Method) structural analysis for the developed models, the safe snow depth was higher 2.3 times than a general roof structure, when elements of equal section modulus were used.

Experimental Investigation of Deck Plate System with Non- Welding Truss Type Deformed Steel Wires (TOX Deck Plate Slab)

김영주,오상훈,윤명호,김희철,변은혁,이영학 한국강구조학회 2009 International Journal of Steel Structures Vol.9 No.4

On the bases of a decreased construction period and convenience of construction, the steel deck plate system has been widely used in the construction field in Korea. In particular, due to its good stiffness and economic considerations, the steel-wireintegrated deck plate system (or truss deck plate system) has become very popular in recent years. But while it offers many advantages, the truss deck plate system has a critical defect: rust forms in the welding joints between the lattice steel wire and the deck plate, resulting in the cracking of these welding joints and water leakage. To address these problems, the TOX deck plate system, a new type of truss deck plate system that does not require welding and does not rust, is proposed in this paper. Tests have been conducted on 15 specimens to evaluate the structural safety of the proposed deck plate system during the construction stage. The test parameters were as follows: the depth of the slab, the length of the span, the diameters of the top, bottom, and lattice steel wire, and the material properties of the zinc-coated steel sheets. The test results show that the TOX deck plate system can guarantee structural safety owing to its deflection and strength. On the bases of a decreased construction period and convenience of construction, the steel deck plate system has been widely used in the construction field in Korea. In particular, due to its good stiffness and economic considerations, the steel-wireintegrated deck plate system (or truss deck plate system) has become very popular in recent years. But while it offers many advantages, the truss deck plate system has a critical defect: rust forms in the welding joints between the lattice steel wire and the deck plate, resulting in the cracking of these welding joints and water leakage. To address these problems, the TOX deck plate system, a new type of truss deck plate system that does not require welding and does not rust, is proposed in this paper. Tests have been conducted on 15 specimens to evaluate the structural safety of the proposed deck plate system during the construction stage. The test parameters were as follows: the depth of the slab, the length of the span, the diameters of the top, bottom, and lattice steel wire, and the material properties of the zinc-coated steel sheets. The test results show that the TOX deck plate system can guarantee structural safety owing to its deflection and strength.