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.

Influencing Factors Analysis of Degradation and Damage and the Effect on Steel Frame

Meng Wang,Yong-Jiu Shi,Yuan-Qing Wang,Wei Guo Yang 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.1

In order to discuss the influencing factors of damage and degradation and the effect on steel frame subject to strongearthquakes, firstly, a constitutive model was proposed for 3D finite element models to calculate the seismic behaviors of steelframe more accurately. The model was proved correct and applicable due to typical quasi-static tests. Then, based on theverified model, the damage and degradation factors were discussed by parametric analyses, including the panel zone, loadinghistory, loading amplitude, the width to thickness ratio and yield strength. The cumulative damage phenomena of steel frameconnections were further studied and the degradation distribution curve was obtained. Finally, the traditional beam elementmodel and proposed shell element model of structure were established by ABAQUS for time history analysis. The effect ofdamage and degradation on seismic behaviors of steel frames were compared and discussed. The tests and analysis resultsrevealed that: panel zone strength, loading amplitude and width-thickness ratios of plates had significant impact on damage anddegradation behaviors and failure modes of connections. Premature weld cracking would lead to earlier damage and degradationunder “strong to weak” earthquake, which would seriously affect the overall mechanical properties of the structure. Once localbuckling caused damage, the results of the beam element model and accurate shell element model were remarkably different. Beam element model without considering damage and degradation underestimated the structural deformations, which shouldbe paid more attention for design safety.

Experimental Study of Lateral-torsional Buckling Behavior of Stainless Steel Welded I-section Beams

Yuanqing Wang,Lu Yang,Bo Gao,Yong-Jiu Shi,Huanxin Yuan 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.2

Investigations on lateral-torsional buckling behavior of stainless steel welded I-section beams were carried out through fourpointbending tests. The Chinese austenitic stainless steel adopted in this study contains approximately 17% of Cr, which couldbe graded as EN 1.4401. The non-linear stress-strain relationship of the material, the residual stress distribution of the sectionand the ultimate moment capacity of the welded I-section beams were obtained from the experiments, and they were comparedwith those results predicted by analytical models recommended by several researchers. Besides, a new model is proposed topredict the residual stress distribution of the stainless steel welded I-section beams.

Theoretical and Exprerimental Sutdy on Interactive Local Buckling of Arch-shaped Corrugated Steel Roof

Li-Li Wu,Xuan-Neng Gao,Yong-Jiu Shi,Yuan-Qing Wang 한국강구조학회 2006 International Journal of Steel Structures Vol.6 No.3

The arch-shaped corugated steel roof is a new type of cold formed thin-waled structure. Since the width-to-thickness ratiosof the plate asemblies of corrugated sections exceed the limits specified in the current design codes, the load-bearingbehavior, especialy loading modes, initial imperfections and boundary conditions, therefore its ultimate load-carying capacityis determined not only by its global stability, but also by its interactive local buckling. In this paper the finite element methodwas aplied to analyze the local buckling behavior of stel arch panels with corrugated trapezium sections. Some tests on theloads to further investigate the loading mechanism of corrugated steel arch panels and the factors refered above. A comparisonbetween the experimental and theoretical results was made, and good agrement was achieved herein. It is shown that therealso exists interactive local buckling among corugated plate assemblies. The experimental results are lower than theoreticalones for axial loading capacity, vice-versa, the former ones are higher for eccentricaly loaded specimens. It is noted that thealso indicate that the trapezium sections have high local buckling capacities, yet they hardly have post-buckling capacities,which are distinctive from that of the plain ones. All these also give some explanations to some corugated steel arch rofscolapsed suddenly in some areas of China.

Anti-neuroinflammatory Effects of 12-Dehydrogingerdione in LPS-Activated Microglia through Inhibiting Akt/IKK/NF-κB Pathway and Activating Nrf-2/HO-1 Pathway

Dong Zhao,Ming-Yao Gu,Jiu Liang Xu,Li Jun Zhang,Shi Yong Ryu,양현옥 한국응용약물학회 2019 Biomolecules & Therapeutics(구 응용약물학회지) Vol.27 No.1

Ginger, one of worldwide consumed dietary spice, is not only famous as food supplements, but also believed to exert a variety of remarkable pharmacological activity as herbal remedies. In this study, a ginger constituent, 12-dehydrogingerdione (DHGD) was proven that has comparable anti-inflammatory activity with positive control 6-shogaol in inhibiting LPS-induced interleukin (IL)-6, tumor necrosis factor (TNF)-α, prostaglandin (PG) E2, nitric oxide (NO), inducible NO synthase (iNOS) and cyclooxygenase (COX)-2, without interfering with COX-1 in cultured microglial cells. Subsequent mechanistic studies indicate that 12-DHGD may inhibit neuro-inflammation through suppressing the LPS-activated Akt/IKK/NF-κB pathway. Furthermore, 12-DHGD markedly promoted the activation of NF-E2-related factor (Nrf)-2 and heme oxygenase (HO)-1, and we demonstrated that the involvement of HO-1 on the production of pro-inflammatory mediators such as NO and TNF-α by using a HO-1 inhibitor, Zinc protoporphyrin (Znpp). These results indicate that 12-DHGD may protect against neuro-inflammation by inhibiting Akt/IKK/IκB/NF-κB pathway and promoting Nrf-2/HO-1 pathway.

Experimental Study on Mechanical Properties and Toughness of Q460C High-strength Steel and Its Butt Welded Joint at Low Temperature

Xi-yue Liu,Yuan-Qing Wang,Liang Zong,Yun Lin,Yong-Jiu Shi 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.3

Compared with the conventional steel structure, the high-strength steel structures are at more risk of brittle fracture, especiallyin cold regions. In the present study, a series of tests (such as uniaxial tensile test, Charpy impact test and three-point bendingtest) were carried out at low temperature to investigate the mechanical properties and toughness of Q460C steel and its buttwelded joint, fracture micro-mechanisms were analyzed as well. The ductility indices and the toughness indices all decreasewith temperature decreases, the heat affected zone (HAZ) in welded joint is more critical to fracture than the base material. The fracture toughness of high-strength steel Q460C is relatively lower than the other three conventional steels (i.e. Q235, Q345and Q390). In this study, rich experimental data were collected so as to provide reference for the fracture resistant design ofhigh-strength steel structures in cold regions.