• Title/Summary/Keyword: Base shear force

Search Result 154, Processing Time 0.02 seconds

아크 용접에서 구동력에 따른 열 및 물질 유동에 관한 연구

  • 김원훈;나석주
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 1996.11a
    • /
    • pp.27-41
    • /
    • 1996
  • In this study the heat transfer and fluid flow of the molten pool in stationary gas tungsten arc welding using argon shielding gas were investigated. Transporting phenomena from the welding arc to the base material surface, such as current density, heat flux, arc pressure and shear stress acting on the weld pool surface, were taken from the simulation results of the corresponding welding arc. Various driving forces for the weld pool convection were considered, self-induced electromagnetic, surface tension, buoyancy, and impinging plasma arc forces. Furthermore, the effect of surface depression due to the arc pressure acting on the molten pool surface was considered. Because fusion boundary has a curved and unknown shape during welding, a boundary-fitted coordinate system was adopted to precisely describe the boundary for the momentum equation. The numerical model was applied to AISI 304 stainless steel and compared with the experimental results.

  • PDF

The effect of base isolation and tuned mass dampers on the seismic response of RC high-rise buildings considering soil-structure interaction

  • Kontoni, Denise-Penelope N.;Farghaly, Ahmed Abdelraheem
    • Earthquakes and Structures
    • /
    • v.17 no.4
    • /
    • pp.425-434
    • /
    • 2019
  • The most effective passive vibration control and seismic resistance options in a reinforced concrete (RC) high-rise building (HRB) are the base isolation and the tuned mass damper (TMD) system. Many options, which may be suitable or not for different soil types, with different types of bearing systems, like rubber isolator, friction pendulum isolator and tension/compression isolator, are investigated to resist the base straining actions under five different earthquakes. TMD resists the seismic response, as a control system, by reducing top displacement or the total movement of the structure. Base isolation and TMDs work under seismic load in a different way, so the combination between base isolation and TMDs will reduce the harmful effect of the earthquakes in an effective and systematic way. In this paper, a comprehensive study of the combination of TMDs with three different base-isolator types for three different soil types and under five different earthquakes is conducted. The seismic response results under five different earthquakes of the studied nine RC HRB models (depicted by the top displacement, base shear force and base bending moment) are compared to show the most suitable hybrid passive vibration control system for three different soil types.

Nonlinear Seismic Analysis of Steel Buildings Considering the Stiffnesses of the Foundation-Soil System (기초지반강성을 고려한 철골 건축구조물의 비선형 지진해석)

  • Oh, Yeong Hui;Kim, Yong Seok
    • Journal of Korean Society of Steel Construction
    • /
    • v.18 no.2
    • /
    • pp.173-180
    • /
    • 2006
  • The seismic responses of a building are affected by the base soil conditions. In this study, linear time-history seismic analysis and nonlinear pushover static seismic analysis were performed to estimate the base shear forces of 3-, 5-, and 7-story steel buildings, considering the rigid and soft soil conditions. Foundation soil stiffness, based on the equivalent static stiffness formula, is used for the damper, one of the Link elements in SAP 2000. The base shear forces of the steel buildings, estimated through time-history analysis using the general-purpose structural-analysis program of SAP 2000, were compared with those calculated using the domestic seismic design code, the UBC-97 design response spectrum. and pushover static nonlinear analysis. The steel buildings designed for gravity and wind loads showed elastic responses with a moderate earthquake of 0.11 g, while the elastic soft-soil layer increased the displacement and the base shear force of the buildings due to soil-structure interaction and soil amplification. Therefore, considering the characteristics of the soft-soil layer, it is more reasonable to perform an elastic seismic analysis of a building's structure during weak or moderate earthquakes.

A Study on Serviceability of Oversized Bolt Hole in High-Tension Bolt Joint Subjected to Bending (휨을 받는 고장력볼트 체결부에서 과대공에 따른 사용성에 관한 연구)

  • Park, Jeong-Ung;Yang, Seung-Hyun;Jang, Suk-In
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.10 no.10
    • /
    • pp.2831-2836
    • /
    • 2009
  • If a design load exceeding the frictional force of the contact surface is applied to the connection of steel members using a high-tension bolt friction joint, sliding occurs and the connection of the steel members bears the design load through the shear strength and bearing strength of the bolt and the base plate. The sliding distance can be determined by the tensile force of the bolt, the friction coefficient of the contact surface, and the position of the bolt in the base plate hole. This study measured and analyzed sliding according to standard bolt hole and oversize bolt hole when pure bending moment and tensile force were applied to high-tension bolt joints with different sizes of bolt holes made in the base plate and the cover plate. In a high-tension bolt joint receiving pure bending moment and tensile force, the load causing sliding in an oversize bolt hole was $74\sim94%$ of that in a standard bolt hole. In a member receiving tensile force, the sliding load ratio was lower when the size of oversize bolt holes in the base plate and the cover plate was large. In addition, the size of the oversize bolt hole in the base plate was more closely correlated with the change of sliding loadthan the size of the oversize bolt hole in the base plate.

Evaluation of the Strength Required in Current Seismic Design Code (현행 내진설계 규준의 수평강도 요구에 대한 평가)

  • 한상환;오영훈;이리형
    • Computational Structural Engineering
    • /
    • v.10 no.4
    • /
    • pp.281-290
    • /
    • 1997
  • Current seismic design code is based on the assumption that the designed structures would be behaved inelastically during a severe earthquake ground motion. For this reason, seismic design forces calculated by seismic codes are much lower than the forces generated by design earthquakes which makes structures responding elastically. Present procedures for calculating seismic design forces are based on the use of elastic spectra reduced by a strength reduction factors known as "response modificaion factor". Because these factors were determined empirically, it is difficult to know how much inelastic behaviors of the structures exhibit. In this study, lateral strength required to maintain target ductility ratio was first calculated from nonlinear dynamic analysis of the single degree of freedom system. At the following step, base shear foeces specified in seismic design code compare with above results. If the base shear force required to maintain target ductility ratio was higher than the code specified one, the lack of required strength should be filled by overstrength and/or redundancy. Therefore, overstrength of moment resisting frame structure will be estimated from the results of push-over analysis.

  • PDF

Wall slip of vaseline in steady shear rheometry

  • Song, Ki-Won;Chang, Gap-Shik;Koo, Ja-Seung
    • Korea-Australia Rheology Journal
    • /
    • v.15 no.2
    • /
    • pp.55-61
    • /
    • 2003
  • The steady shear flow properties of vaseline generally used as a base of the pharmaceutical dosage forms were studied in the consideration of wall slip phenomenon. The purpose of this study was to show that how slip may affect the experimental steady-state flow curves of semisolid ointment bases and to discuss the ways to eliminate (or minimize) wall slip effect in a rotational rheometer. Using both a strain-controlled ARES rheometer and a stress-controlled AR1000 rheometer, the steady shear flow behavior was investigated with various experimental conditions ; the surface roughness, sample preparation, plate diameter, gap size, shearing time, and loading methods were varied. A stress-controlled rheometer was suitable for investigating the flow behavior of semisolid ointment bases which show severe wall slip effects. In the conditions of parallel plates attached with sand paper, treated sample, smaller diameter fixture, larger gap size, shorter shearing time, and normal force control loading method, the wall slip effects could be minimized. A critical shear stress for the onset of slip was extended to above 10,000 dyne/$\textrm{cm}^2$. The wall slip effects could not be perfectly eliminated by any experimental conditions. However, the slip was delayed to higher value of shear stress by selecting proper fixture properties and experimental conditions.

Effect of seismic pounding on buildings isolated by triple friction pendulum bearing

  • Amiri, Gholamreza Ghodrati;Shakouri, Ayoub;Veismoradi, Sajad;Namiranian, Pejman
    • Earthquakes and Structures
    • /
    • v.12 no.1
    • /
    • pp.35-45
    • /
    • 2017
  • The current paper investigates the effect of the seismic pounding of neighboring buildings on the response of structures isolated by Triple Friction Pendulum Bearing (TFPB). To this end, a symmetric three-dimensional single story building is modeled for analysis with two specified levels of top deck and base deck, to capture the seismic response of the base isolators and building's roof. Linear elastic springs with different level of gaps are employed to calculate the impact between the buildings. Nonlinear Dynamic Time History Analyses (NDTHA) are conducted for seismic evaluation. Also, five different sizes with four different sets of friction coefficients are assumed for base isolators to cover a whole range of base isolation systems with various geometry configurations and fundamental period. The results are investigated in terms of base shear, buildings' drift and top deck acceleration of the superstructure. The results also indicate the profound effect of the stiffness of the adjacent buildings on the value of the impact they impose to the superstructure. Also, in situations of potential pounding, the increment of the fundamental period of the TFPB base isolator could intensify the impact force up to nearly five-fold.

A Seismic Behavior of a 3-dimensional Irregular Setback Structure (3차원 비정형 Setback 구조물의 지진 거동)

  • 문성권
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.13 no.1
    • /
    • pp.105-113
    • /
    • 2000
  • Seismic behavior of 3-dimensional setback structures showing abrupt reductions of the floor size within the structure height and the effect of in-plane deformations of floor slabs on the seismic behavior of those structures are investigated. To find out general seismic behavior of 3-dimensional setback structures two parameters, level of setback(L/sub s/) and degree of setback(R/sub s/) are used. Analysis results obtained from forty eight setback structures show that a sudden change in story shear near setback level is occurred for irregular setback structures. The effect of in-plane deformation of floor slabs on the seismic behavior of setback structures is greatly influenced by the arrangement of lateral load resisting elements and it is more pronounced for frame-shear wall system showing large difference in stiffness among the lateral load resisting elements. The in-plane deformation of floor slabs results in reduced base shear, especially for FW-type structures with L/sub s/=1.0. Also, it brings about reduced story shear for the lateral load resisting element with shear wall and increase in story shear lot the lateral load resisting element without shear wall. The in-plane deformation of floor slabs at the base portion and/or tower portion due to difference in stiffness among the lateral load resisting elements brings about increment of floor displacements at all floor level.

  • PDF

Inelastic Time History Analysis of a Five-Story Steel Framed Structure Considering Rigidity of TSD Connection (TSD 접합부의 강성을 고려한 5층 철골골조구조물의 비탄성 시간이력해석)

  • Kang, Suk-Bong;Lee, Jae-Hwan
    • Journal of Korean Society of Steel Construction
    • /
    • v.22 no.3
    • /
    • pp.281-291
    • /
    • 2010
  • In this study, a five-story steel frame was designed in accordance with KBC2005 to evaluate the effects of the beam-column connection on the structural behavior. The connections were designed as fully rigid and semi-rigid. The fiber model was used to describe the moment-curvature relationship of the steel beam and the column, the power model for the moment-rotation angle of the semi-rigid connection and the three-parameter model for the hysteretic behavior of the steel beam, column, and connection. The structure was idealized as separate 2-D frames and as connected 2-D frames. The peak ground accelerations of four earthquake records were modified in a time-history analysis for the levels of the mean return period and for the maximum base-shear force in a pushover analysis. The top story displacement, base-shear force, story drift, demanded ductility ratio for the semi-rigid connection, maximum bending moment of the column, beam, and connection, and distribution of the plastic hinge were examined in the time-history analysis. The frame with the semi-rigid connection yielded a lower base-shear force, less magnitude, and increasing ratio in the bending moment of the column, beam, and connection than the frame with a fully rigid connection. The TSD connection was deemed to have secured the economy and safety of the sample structure that was subjected to seismic excitation for the Korean design level.

An Analytical Study on the Bond-Properties of Axial Bars Embedded in Massive Concrete (매시브콘크리트에 배근된 주철근의 부착특성에 관한 해석적 연구)

  • 장일영;이호범;이승훈;변근주
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1992.04a
    • /
    • pp.143-147
    • /
    • 1992
  • Description of the behavior of the R.C structural members fixed on massive concrete is not normally generalization of recognized configuration for regular R.C. design guidanes. This can be due to the complexity of evaluation of internal resistancy and deflection changes of the members subjected to the various external forces. On the base of axially loaded member fixed on footing, however, the estimation of deflection changes due to flexural force shear force and rotational force is to be carried out in ways of specifying the bond characteristics of axial bars embedded in massive concrete. This work is to quantify adhesion of steel-concrete, initial concrete cracking stress near bar rib, maximum bond stress and residual stress in concrete respectively. In addition to quantification of them for particulate behavior, the suggestions of multi-linear bond stress-slip diagram made in carrying out finite element analyses for adhesion failure, examining concrete cracking status and reviewing existing experimental data lead to alternatively constructed relationship between bond stress and slip for a axial bars embedded massive concrete.

  • PDF