• Title/Summary/Keyword: lateral drift

Search Result 57, Processing Time 0.125 seconds

Computational method in database-assisted design for wind engineering with varying performance objectives

  • Merhi, Ali;Letchford, Chris W.
    • Wind and Structures
    • /
    • v.32 no.5
    • /
    • pp.439-452
    • /
    • 2021
  • The concept of Performance objective assessment is extended to wind engineering. This approach applies using the Database-Assisted Design technique, relying on the aerodynamic database provided by the National Institute of Standards and Technology (NIST). A structural model of a low-rise building is analyzed to obtain influence coefficients for internal forces and displacements. Combining these coefficients with time histories of pressure coefficients on the envelope produces time histories of load effects on the structure, for example knee and ridge bending moments, and eave lateral drift. The peak values of such effects are represented by an extreme-value Type I Distribution, which allows the estimation of the gust wind speed leading to the mean hourly extreme loading that cause specific performance objective compromises. Firstly a fully correlated wind field over large tributary areas is assumed and then relaxed to utilize the denser pressure tap data available but with considerably more computational effort. The performance objectives are determined in accordance with the limit state load combinations given in the ASCE 7-16 provisions, particularly the Load and Resistance Factor Design (LRFD) method. The procedure is then repeated for several wind directions and different dominant opening scenarios to determine the cases that produce performance objective criteria. Comparisons with two approaches in ASCE 7 are made.

Practical Design Method for Coupling Beams of Tall Buildings with Dual Frame System (이중골조형식 고층건물 커플링보의 실용설계)

  • Yoon, Tae-Ho;Kim, Jin-Sang
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.15 no.1
    • /
    • pp.525-532
    • /
    • 2014
  • In this study, practical design method of coupling beams is proposed. The member forces varies according to the location of the members and the members at 25%~40% of building height shows large member forces. The 100mm increase of wall thickness causes 3~4% variation of member forces and the 100MPa increase of concrete strength decrease approximately 3% of member forces. The required strength of coupling beams is twice the resistant strength and 80% reduction of coupling beam stiffness is necessary to fulfill the design criteria. The stiffness reduction of coupling beams is not necessary over the entire stories and the strength reduction range can be estimated considering design requirements.

A Study on the Development of Force Limiting Devices of Folded Plate Type (절판형 응력제한 기구의 개발에 관한 연구)

  • Kim, Cheol Hwan;Chae, Won Tak
    • Journal of Korean Society of Steel Construction
    • /
    • v.26 no.6
    • /
    • pp.571-579
    • /
    • 2014
  • The steel braces are used to control the lateral drift of high rise buildings. The braces are designed as tensile members since the braces consisted of slender member can not resist compressive loads by elastic buckling. To resolve this problem, a lot of research were performed to develop the non-buckling member. The force limiting device (FLD.) is one of them. The purpose of this study is the development of FLD. to prevent a elastic buckling for a slender member. The folded plate type is proposed to induce the yielding before occurring elastic buckling. In this study, member test and FEM analysis for proposed type were performed. Further, It is verified that the structure with FLD member is stable by high energy absorption. The proposed folded plate type FLD could be effective to preserve the compressive member from the elastic buckling.

Design Method to Control Wind-Induced Vibration of High-Rise Buildings Using Resizing Algorithm (재분배기법을 이용한 고층건물의 풍응답 가속도 조절 설계기법)

  • Seo, Ji-Hyun;Park, Hyo-Seon
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.23 no.5
    • /
    • pp.465-473
    • /
    • 2010
  • As increase of height and slenderness of buildings, serviceability design criteria such as maximum lateral drift and wind-induced vibration level play an important role in structural design of high-rise buildings. Especially, wind-induced vibration is directly related to discomfort of occupants. However, no practical algorithm or design method is available for structural designers to control the acceleration level due to wind. This paper presented a control method for wind-induced vibration of high-rise buildings using the resizing algorithm. The level of vibration due to wind is calculated by well known estimation rules of ASCE 7-02, NBCC 95, SAA83, and Solari method. Based on the fact that the level of wind-induced vibration is inversely proportional to the magnitude of natural periods of buildings, in the design method, natural periods of a high-rise building are modified by redistribution of structural weight according to the resizing algorithm. The design method is applied to wind-induced vibration control design of real 42-story residential building and evaluated the efficiency and effectiveness.

Development of Resizing Techniques for Drift Designs of High-rise Buildings subjected to Lateral and Vertical Loads (횡하중과 연직하중을 받는 고층건물의 변위설계를 위한 재분배기법 개발)

  • 서지현;박효선
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.17 no.1
    • /
    • pp.49-58
    • /
    • 2004
  • Drift design of a high-rise building is a governing factor in the determination of structural weights and lateral resisting systems. However, high-rise buildings are composed of tens of thousands of structural member, designer can not know which members are active to lateral drift control and how much they contribute to lateral drifts. Resizing technique was proved to be a practical method for drift design of high-rise buildings. However, no resizing algorithm has been considered the effect of vertical loads in drift designs. Thus, in this paper, a resizing algorithm has been developed for drift designs of high-rise buildings subjected to both lateral and vertical loads. The drift design model has been applied to drift designs of two high-rise building examples.

Cyclic Lateral Load Test on the Punching Shear Strength and the Lateral Displacement Capacity of Slab-Column Connections (슬래브-기둥 접합부의 펀칭강도 및 횡변위 성능에 관한 반복 횡하중 실험)

  • Choi, Jung-Wook;Song, Jin-Gyu;Kim, Jun-Hee
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.11 no.4
    • /
    • pp.99-108
    • /
    • 2007
  • In the flat-plate slab design of the KCI and ACI building code, the punching shear strength of connections with shear reinforcement can increase one and half times to that of connections without shear reinforcement. And the ACI-ASCE committee 352 recommendations propose limiting the direct shear ratio $V_g$/$V_c$ on interior connections to 0.4 to insure adequate drift capacity. In this study, four interior column-slab connections were tested to look into the punching shear strength and the lateral displacement capacity of the flat-plate slab with and without shear reinforcement under cyclic lateral loading. Based on the test results, it is found that the provision about punching shear strength in the codes may appropriate for the gravity loading only whereas it is unconservative for the lateral loading and that the limit of ACI-ASCE committee 352 appears conservative.

Nonlinear Analysis of Precast Concrete Wall Structures (프리캐스트 콘크리트 판구조의 비선형 해석)

  • 서수연;이원호;이리형
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.13 no.2
    • /
    • pp.189-196
    • /
    • 2000
  • The objective of this paper is to propose an analysis technique to predict the behavior of PC wall structures subjected to cyclic load. While PC wall panel is idealized by finite elements, the joints at which PC walls are connected each other are idealized by nonlinear spring elements. Axial and shear spring elements are developed for simulating shear, compression and tension behaviors of joints. The strength and stiffness of each spring elements we presented from the previous research results and incorporated into the computer program of DRAIN-2DX. The proposed analysis technique is evaluated by analyzing specimens previously tested and comparing with those. On the strength, stiffness, energy dissipation and lateral drift, analytical results show good agreements with test results. This means the proposed technique is effective to predict the response of the PC wall structures.

  • PDF

Embossed Structural Skin for Tall Buildings

  • Song, Jin Young;Lee, Donghun;Erikson, James;Hao, Jianming;Wu, Teng;Kim, Bonghwan
    • International Journal of High-Rise Buildings
    • /
    • v.7 no.1
    • /
    • pp.17-32
    • /
    • 2018
  • This paper explores the function of a structural skin with an embossed surface applicable to use for tall building structures. The major diagrid system with a secondary embossed surface structure provides an enhanced perimeter structural system by increasing tube section areas and reduces aerodynamic loads by disorienting major organized structure of winds. A parametric study used to investigate an optimized configuration of the embossed structure revealed that the embossed structure has a structural advantage in stiffening the structure, reducing lateral drift to 90% compared to a non-embossed diagrid baseline model, and results of wind load analysis using computational fluid dynamics, demonstrated the proposed embossed system can reduce. The resulting undulating embossed skin geometry presents both opportunities for incorporating versatile interior environments as well as unique challenges for daylighting and thermal control of the envelope. Solar and thermal control requires multiple daylighting solutions to address each local façade surface condition in order to reduce energy loads and meet occupant comfort standards. These findings illustrate that although more complex in geometry, architects and engineers can produce tall buildings that have less impact on our environment by utilizing structural forms that reduce structural steel needed for stiffening, thus reducing embodied $CO^2$, while positively affecting indoor quality and energy performance, all possible while creating a unique urban iconography derived from the performance of building skin.

Comparisons of Numerical Analyses considering the Effects of Shear Strength Degradation For Nonseismic Designed RC Frame (비내진 설계된 RC 골조에 대한 전단강도 감소 효과를 고려한 수치해석의 비교)

  • Lee, Young-Wook
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.10 no.1
    • /
    • pp.1-8
    • /
    • 2006
  • Nonseismic designed RC frame have a possibility of shear failure because of deficiencies of reinforcing details. To model the shear failure in numerical analysis, shear strength degradation models which Include Moehle's and ATC 40 are compared and applied to push-over analysis. For numerical analysis, three storied building frame is selected and designed according to Korean Concrete Design Code(2003). As results, It is shown that Moehle's shear strength degradation model estimates the shear strength lower than NZSEE model and has less variation than ATC 40 model and all the shear strengths of models are greater than the nominal shear strength of ACI 318. Also, from the numerical analysis, it is pointed out that there may be great difference in lateral drift capacity if a different shear strength model is used. And the capacity can be severely underestimated if the restraining model of plastic rotation of ATC 40 is used, compared to the use of shear spring model for shear degradation.

ROAD CROWN, TIRE, AND SUSPENSION EFFECTS ON VEHICLE STRAIGHT-AHEAD MOTION

  • LEE J-H.;LEE J. W.;SUNG I. C.
    • International Journal of Automotive Technology
    • /
    • v.6 no.2
    • /
    • pp.183-190
    • /
    • 2005
  • During normal operating conditions, a motor vehicle is constantly subjected to a variety of forces, which can adversely affect its straight-ahead motion performance. These forces can originate both from external sources such as wind and road and from on-board sources such as tires, suspension, and chassis configuration. One of the effects of these disturbances is the phenomenon of vehicle lateral-drift during straight-ahead motion. This paper examines the effects of road crown, tires, and suspension on vehicle straight-ahead motion. The results of experimental studies into the effects of these on-board and external disturbances are extremely sensitive to small changes in test conditions and are therefore difficult to guarantee repeatability. This study was therefore conducted by means of computer simulation using a full vehicle model. The purpose of this paper is to gain further understanding of the straight-ahead maneuver from simulation results, some aspects of which may not be obtainable from experimental study. This paper also aims to clarify some of the disputable arguments on the theories of vehicle straight-ahead motion found in the literature. Tire residual aligning torque, road crown angle, scrub radius and caster angle in suspension geometry, were selected as the study variables. The effects of these variables on straight-ahead motion were evaluated from the straight-ahead motion simulation results during a 100m run in free control mode. Examination of vehicle behavior during straight-ahead motion under a fixed control mode was also carried out in order to evaluate the validity of several disputable arguments on vehicle pull theory, found in the literature. Finally, qualitative comparisons between the simulation results and the test results were made to support the validity of the simulation results.