• Title, Summary, Keyword: high-strength steel (HSS)

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Seismic performance of eccentrically braced frames with high strength steel combination

  • Lian, Ming;Su, Mingzhou;Guo, Yan
    • Steel and Composite Structures
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    • v.18 no.6
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    • pp.1517-1539
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    • 2015
  • Eccentrically braced frames (EBFs) often use conventional steel with medium yield strength. This system requires structural members with large cross-sections for well seismic behavior, which leads to increased material costs. In eccentrically braced frames with high strength steel combination (HSS-EBFs), links use Q345 steel (specified nominal yield strength 345 MPa), braces use Q345 steel or high strength steel while other structural members use high strength steel (e.g., steel Q460 with the nominal yield strength of 460 MPa or steel Q690 with the nominal yield strength of 690 MPa). For this approach can result in reduced steel consumption and increased economic efficiency. Several finite element models of both HSS-EBFs and EBFs are established in this paper. Nonlinear hysteretic analyses and nonlinear time history analyses are conducted to compare seismic performance and economy of HSS-EBFs versus EBFs. Results indicate that the seismic performance of HSS-EBFs is slightly poorer than that of EBFs under the same design conditions, and HSS-EBFs satisfy seismic design codes and reduce material costs.

Experimental performance of Y-shaped eccentrically braced frames fabricated with high strength steel

  • Lian, Ming;Su, Mingzhou;Guo, Yan
    • Steel and Composite Structures
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    • v.24 no.4
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    • pp.441-453
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    • 2017
  • In Y-shaped eccentrically braced frame fabricated with high strength steel (Y-HSS-EBF), link uses conventional steel while other structural members use high strength steel. Cyclic test for a 1:2 length scaled one-bay and one-story Y-HSS-EBF specimen and shake table test for a 1:2 length scaled three-story Y-HSS-EBF specimen were carried out to research the seismic performance of Y-HSS-EBF. These include the failure mode, load-bearing capacity, ductility, energy dissipation capacity, dynamic properties, acceleration responses, displacement responses, and dynamic strain responses. The test results indicated that the one-bay and one-story Y-HSS-EBF specimen had good load-bearing capacity and ductility capacity. The three-story specimen cumulative structural damage and deformation increased, while its stiffness decreased. There was no plastic deformation observed in the braces, beams, or columns in the three-story Y-HSS-EBF specimen, and there was no danger of collapse during the seismic loads. The designed shear link dissipated the energy via shear deformation during the seismic loads. When the specimen was fractured, the maximum link plastic rotation angle was higher than 0.08 rad for the shear link in AISC341-10. The Y-HSS-EBF is a safe dual system with reliable hysteretic behaviors and seismic performance.

Bead Optimization to Reduce Springback of Sheet Metal Forming using High Strength Steel (HSS강판 판재성형 시 스프링백 최소화를 위한 드로우 비드 최적 설계)

  • Hong, Seokmoo;Hwang, Jihoon
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.23 no.4
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    • pp.350-354
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    • 2014
  • Recently, high strength steel (HSS) sheet metal has been widely used to improve lightweight structures in the automotive industry. Because HSS sheets have high strength but low elongation, it is difficult both to make products with complex shapes and to control excessive springback. In order to reduce the springback after forming using HSS, draw beads were introduced in this study. The design variables, including the draw-bead positions and shapes, were optimized using a finite element analysis. A mold for a scanner support, which is part of an A3 printer, was designed using the proposed method and then utilized. The results from a finite element simulation and optimization were compared with the experiment results.

Flexural behaviour of square UHPC-filled hollow steel section beams

  • Guler, Soner;Copur, Alperen;Aydogan, Metin
    • Structural Engineering and Mechanics
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    • v.43 no.2
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    • pp.225-237
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    • 2012
  • This paper presents an experimental investigation of the flexural behavior of square hollow steel section (HSS) beams subjected to pure bending. Totally six unfilled and nine ultra high performance concrete (UHPC)-filled HSS beams were tested under four-point bending until failure. The effects of the steel tube thickness, the yield strength of the steel tube and the strength of concrete on moment capacity, curvature, and ductility of UHPC-filled HSS beams were examined. The performance indices named relative ductility index (RDI) and strength increasing factor (SIF) were investigated with regard to different height-to-thickness ratio of the specimens. The flexural strengths obtained from the tests were compared with the values predicted by Eurocode 4, AISC-LRFD and CIDECT design codes. The results showed that the increase in the moment capacity and the corresponding curvature is much greater for thinner HSS beams than thicker ones. Eurocode 4 and AISC-LRFD predict the ultimate moment capacity of the all UHPC-filled HSS beams conservatively.

Seismic behavior of K-type eccentrically braced frames with high strength steel based on PBSD method

  • Li, Shen;Wang, Chao-yu;Li, Xiao-lei;Jian, Zheng;Tian, Jian-bo
    • Earthquakes and Structures
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    • v.15 no.6
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    • pp.667-685
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    • 2018
  • In eccentrically braced steel frames (EBFs), the links are fuse members which enter inelastic phase before other structure members and dissipate the seismic energy. Based on the force-based seismic design method, damages and plastic deformations are limited to the links, and the main structure members are required tremendous sizes to ensure elastic with limited or no damage. Force-based seismic design method is very common and is found in most design codes, it is unable to determine the inelastic response of the structure and the damages of the members. Nowadays, methods of seismic design are emphasizing more on performance-based seismic design concept to have a more realistic assessment of the inelastic response of the structure. Links use ordinary steel Q345 (the nominal yielding strength $f_y{\geq}345MPa$) while other members use high strength steel (Q460 $f_y{\geq}460MPa$ or Q690 $f_y{\geq}690MPa$) in eccentrically braced frames with high strength steel combination (HSS-EBFs). The application of high strength steels brings out many advantages, including higher safety ensured by higher strength in elastic state, better economy which results from the smaller member size and structural weight as well as the corresponding welding work, and most importantly, the application of high strength steel in seismic fortification zone, which is helpful to popularize the extensive use of high strength steel. In order to comparison seismic behavior between HSS-EBFs and ordinary EBFs, on the basis of experimental study, four structures with 5, 10, 15 and 20 stories were designed by PBSD method for HSS-EBFs and ordinary EBFs. Nonlinear static and dynamic analysis is applied to all designs. The loading capacity, lateral stiffness, ductility and story drifts and failure mode under rare earthquake of the designs are compared. Analyses results indicated that HSS-EBFs have similar loading capacity with ordinary EBFs while the lateral stiffness and ductility of HSS-EBFs is lower than that of EBFs. HSS-EBFs and ordinary EBFs designed by PBSD method have the similar failure mode and story drift distribution under rare earthquake, the steel weight of HSS-EBFs is 10%-15% lower than ordinary EBFs resulting in good economic efficiency.

Spatial substructure hybrid simulation tests of high-strength steel composite Y-eccentrically braced frames

  • Li, Tengfei;Su, Mingzhou;Sui, Yan
    • Steel and Composite Structures
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    • v.34 no.5
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    • pp.715-732
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    • 2020
  • High-strength steel composite Y-eccentrically braced frame (Y-HSS-EBF) is a novel structural system. In this study, the spatial substructure hybrid simulation test (SHST) method is used to further study the seismic performance of Y-HSS-EBF. Firstly, based on the cyclic loading tests of two single-story single-span Y-HSS-EBF planar specimens, a finite element model in OpenSees was verified to provide a reference for the numerical substructure analysis model for the later SHST. Then, the SHST was carried out on the OpenFresco test platform. A three-story spatial Y-HSS-EBF model was taken as the prototype, the top story was taken as the experimental substructure, and the remaining two stories were taken as the numerical substructure to be simulated in OpenSees. According to the test results, the validity of the SHST was verified, and the main seismic performance indexes of the SHST model were analyzed. The results show that, the SHST based on the OpenFresco platform has good stability and accuracy, and the results of the SHST agree well with the global numerical model of the structure. Under strong seismic action, the plastic deformation of Y-HSS-EBF mainly occurs in the shear link, and the beam, beam-columns and braces can basically remain in the elastic state, which is conducive to post-earthquake repair.

Shake table test of Y-shaped eccentrically braced frames fabricated with high-strength steel

  • Lian, Ming;Su, Mingzhou
    • Earthquakes and Structures
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    • v.12 no.5
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    • pp.501-513
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    • 2017
  • To investigate the seismic performance of Y-shaped eccentrically braced frames fabricated with high-strength steel (Y-HSS-EBFs), a shake table test of a 1:2 scaled three-story Y-HSS-EBF specimen was performed. The input wave for the shake table test was generated by the ground motions of El Centro, Taft, and Lanzhou waves. The dynamic properties, acceleration, displacement, and strain responses were obtained from the test specimen and compared with previous test results. In addition, a finite element model of the test specimen was established using the SAP2000 software. Results from the numerical analysis were compared with the test specimen results. During the shake table test, the specimen exhibited sufficient overall structural stiffness and safety but suffered some localized damage. The lateral stiffness of the structure degenerated during the high seismic intensity earthquake. The maximum elastic and elastoplastic interstory drift of the test specimen for different peak ground accelerations were 1/872 and 1/71, respectively. During the high seismic intensity earthquake, the links of the test specimen entered the plastic stage to dissipate the earthquake energy, while other structural members remained in the elastic stage. The Y-HSS-EBF is a safe, dual system with reliable seismic performance. The numerical analysis results were in useful agreement with the test results. This finding indicated that the finite element model in SAP2000 provided a very accurate prediction of the Y-HSS-EBF structure's behavior during the seismic loadings.

A Study on fatigue Strength in the Friction Welded Joints of HSS-Co to SM55C Carbon Steel(I) (HSS-Co와 SM55C 이종 마찰용접재의 피로강도에 관한 연구(1))

  • 서창민;서덕영;이동재
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.4
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    • pp.918-928
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    • 1995
  • This paper deals with the various mechanical properties and fatigue strength in the FRW1 (friction welded interface) of high speed steel (HSS-Co) to SM55C through the tensile test, hardness test and fatigue test. The data of FRW specimens are also compared with those of the base materials (HSS-Co and SM55C steel). Three kinds of specimens used in this study are the friction welded joints, HSS-Co and SM55C carbon steel with circumferential notch, saw notch and smooth, respectively. It is confirmed that the applied welding conditions are optimum methods in order to minimize the heat affected zone (HAZ) and hardness distribution at the HAZ. The fatigue strengths at N = 10$^{6}$ cycles of smooth, circumferential notch and saw notch specimens in the FRW joints are about 299.2 MPa, 123.8 MPa and 247.5 MPA, respectively. The fatigue strength of the friction welded joints is almost equal to that of the SM55C carbon steel in the optimum welding conditions. The fatigue cracks initiated at the welded zone are propagated along the side of SM55C steel.

Processing and Mechanical Properties of Mullite Fiber / Fe Composite

  • Niibo, Yoshihide;Yuchi, Kazuhiro;Sameshima, Soichiro;Hirata, Yoshihiro
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • pp.195-214
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    • 2000
  • The high-speed steel (shorten as HSS) consists of Fe and several kinds of transition metal carbides. The cutting tools or wear-resistant materials made from HSS experience relatively high thermal shock because a coolant such as water or oil is flowed over the surface of heated HSS. The purpose of this research is to increase the hardness, strength, fracture toughness and thermal shock resistance of HSS. A possible strategy is to incorporate a hard ceramic material with high strength in HSS matrix. This paper describes the processing, microstructure and mechanical properties of the oriented unidirectional mullite fiber/HSS composite. The unidirectional mullite fibers of 10${\mu}{\textrm}{m}$ diameter were dispersed by the ultrasonic irradiation of 38 kHz in an ethylenglycol suspension containing HSS powder of 11${\mu}{\textrm}{m}$ median size. The dried green composites with 4-68 vol% fibers were hot-pressed for 2h at 100$0^{\circ}C$ in Ar atmosphere under a pressure of 39 MPa. The higher density was achieved in the composite with a lower content of fibers. The oriented unidirectional fibers were well dispersed in the HSS matrix. The average distance between the center of fibers in the cross section was close to the value calculated from the fiber fraction. No reaction occurred at the interfaces between HSS and mullite fibers in the composites. The composite with 13.6 vol% fibers showed 100 MPa of four point flexural strength at room temperature. The thermal expansion of composite with heating was influenced by the orientation of mullite fibers.

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Contact Pressure Effect on Frictional Behavior of Sheet Steel for Automotive Stamping (자동차용 강판의 표면 마찰 특성에 대한 접촉 압력의 영향)

  • Han, S.S.
    • Transactions of Materials Processing
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    • v.20 no.2
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    • pp.99-103
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    • 2011
  • Many parameters influence the frictional behavior of steel sheet during stamping. The contact pressure between a die and a sheet during stamping is one of them. Thus, this parameter is investigated for high strength steel (HSS) sheets, which are widely used for auto body panels due to their potential for weight reduction. Since HSS extend the limits of contact pressure for mild steel, the effect of this parameter on friction cannot be ignored. To investigate the influence of contact pressure on the frictional behavior of steel sheets, a flat type of friction test was conducted on three different steel sheets under various contact pressures. For bare steel sheets, the curve representing the relationship between contact pressure and friction coefficient exhibits a U shape. Coated steel sheets show a similar tendency except at low contact pressure. For these materials, when the contact pressure is very low, the friction coefficient slightly increases with pressure before it starts to decrease. The test results show that the effect of contact pressure on frictional behavior of steel sheet is not negligible even for contact pressures that are lower than the strength of HSS sheet.