• Title/Summary/Keyword: SDOF model

Search Result 77, Processing Time 0.019 seconds

Estimation of Nonlinear Response for Moment Resisting Reinforced Concrete Frames Using Equivalent SDOF System (등가 1 자유도계에 의한 철근콘크리트 건물의 비선형 동적해석의 검토)

  • 전대한;노필성
    • Proceedings of the Earthquake Engineering Society of Korea Conference
    • /
    • 2003.09a
    • /
    • pp.205-212
    • /
    • 2003
  • To evaluate the seismic performance of multistory building structures use an equivalent SDOF model. This paper presents a method of converting a MDOF system into an equivalent SDOF model. The principal objective of this investigation is to evaluate appropriateness of converting method through perform nonlinear time history analysis of a multistory building structures and an equivalent SDOF model. The hysteresis rules to be used an equivalent SDOF model is obtained from the pushover analysis. The conclusion of this study is following; A method of converting a MDOF system into an equivalent SDOF model through the nonlinear time history response analysis is valid. The representative lateral displacement of a moment resisting reinforced concrete frames is close to the height of the first modal participation vector $_1$$\beta$$_1$u}=1. It can be found that the hysteresis rule of an equivalent SDOF model have influence on the time history response. Therefore, it is necessary for selecting hysteresis rules to consider hysteresis characteristics of a moment resisting reinforced concrete frames.

  • PDF

Analytical study of wind-rain-induced cable vibration : 2DOF model

  • Wang, L.Y.;Xu, Y.L.
    • Wind and Structures
    • /
    • v.6 no.4
    • /
    • pp.291-306
    • /
    • 2003
  • Many investigations have been conducted to find out the reason behind wind-rain-induced cable vibration in cable-stayed bridges. A single-degree-of-freedom (SDOF) analytical model, which could capture main features of wind-rain-induced cable vibration, was recently presented by the writers. This paper extends the SDOF model to a 2DOF model by including the equation of motion of upper rivulet. The interaction between the upper rivulet and the cable is described in terms of nonlinear damping force, linear restoring force, and inertia force. The computed results using the 2DOF model are first compared with the results from simulated wind-rain tunnel tests, and the comparison is found satisfactory in general. The possible mechanisms of wind-rain-induced cable vibration are discussed and a parametric study is then conducted. Finally, the computed results using the 2DOF model are compared with those predicted by the SDOF model. The 2DOF model is found better than the SDOF model but the SDOF model is still acceptable for its simplicity.

Estimation of Interstory Drift for Moment Resisting Reinforced Concrete Frames Using Equivalent SDOF System (등가 1자유도계를 이용한 철근콘크리트 골조건물의 층간변위 응답 산정)

  • Kang, Ho-Geun;Jun, Dae-Han
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.8 no.5 s.39
    • /
    • pp.25-33
    • /
    • 2004
  • To evaluate the seismic capacity of a multistorey building structures in performance based seismic design, it is needed to convert MDOF model into equivalent SDOF model. This paper presents predictions for interstory drift of multistorey structures using method of converting a MDOF system into an equivalent SDOF model. The principal objective of this investigation is to evaluate appropriateness of converting method through performing nonlinear time history analysis of a multistory building structures and an equivalent SDOF model. Comparing the interstory drift of multistorey structures calculated by time history analysis and those evaluated by an equivalent SDOF model, the adequacy and the validity of converting method is verified. The conclusion of this study is following; A method of converting a MDOF system into an equivalent SDOF model through the nonlinear time history response analysis is valid. Inelastic first mode shapes are expected to be more accurate than elastic first mode shapes in obtaining interstory drift of multistorey structures from equivalent SDOF model.

A new SDOF method of one-way reinforced concrete slab under non-uniform blast loading

  • Wang, Wei;Zhang, Duo;Lu, Fangyun;Liu, Ruichao
    • Structural Engineering and Mechanics
    • /
    • v.46 no.5
    • /
    • pp.595-613
    • /
    • 2013
  • A new effective model for calculation of the equivalent uniform blast load for non-uniform blast load such as close-in explosion of a one-way square and rectangle reinforced concrete slab is proposed in this paper. The model is then validated using single degree of freedom (SDOF) system with the experiments and blast tests for square slabs and rectangle slabs. Test results showed that the model is accurate in predicting the damage level on the tested RC slabs under the given explosive charge weight and stand-off distance especially for close-in blast load. The results are also compared with those obtained by conventional SDOF analysis and finite element (FE) analysis using solid elements. It is shown that the new model is more accurate than the conventional SDOF analysis and is running faster than the FE analysis.

The influence of load pulse shape on pressure-impulse diagrams of one-way RC slabs

  • Wang, Wei;Zhang, Duo;Lu, Fangyun
    • Structural Engineering and Mechanics
    • /
    • v.42 no.3
    • /
    • pp.363-381
    • /
    • 2012
  • This study is aimed at providing an efficient analytical model to obtain pressure- impulse diagram of one-way reinforced concrete slabs subjected to different shapes of air blast loading using single degree of freedom method (SDOF). A tri-linear elastic perfectly plastic SDOF model has been used to obtain the pressure-impulse diagram to correlate the blast pressure and the corresponding concrete flexural damage. In order to capture the response history for the slab, a new approximately SDOF method based on the conventional SDOF method is proposed and validated using published test data. The influences of pulse loading shape on the pressure-impulse diagram are studied. Based on the results, a pressure-impulse diagram generation method using SDOF and an analytical equation for the pressure-impulse diagram is proposed to different damage levels and different blast loading shapes.

Inelastic two-degree-of-freedom model for roof frame under airblast loading

  • Park, Jong Yil;Krauthammer, Theodor
    • Structural Engineering and Mechanics
    • /
    • v.32 no.2
    • /
    • pp.321-335
    • /
    • 2009
  • When a roof frame is subjected to the airblast loading, the conventional way to analyze the damage of the frame or design the frame is to use single degree of freedom (SDOF) model. Although a roof frame consists of beams and girders, a typical SDOF analysis can be conducted only separately for each component. Thus, the rigid body motion of beams by deflections of supporting girders can not be easily considered. Neglecting the beam-girder interaction in the SDOF analysis may cause serious inaccuracies in the response values in both Pressure-Impulse curve (P-I) and Charge Weight-Standoff Diagrams (CWSD). In this paper, an inelastic two degrees of freedom (TDOF) model is developed, based on force equilibrium equations, to consider beam-girder interaction, and to assess if the modified SDOF analysis can be a reasonable design approach.

An SDOF model of a four-sided fixed RC wall having an opening for blast response simulation

  • S.H., Sung;H., Ji
    • Structural Engineering and Mechanics
    • /
    • v.84 no.5
    • /
    • pp.675-684
    • /
    • 2022
  • The conventional single-degree-of-freedom (SDOF) system is appropriate for dynamic response analysis of paneltype structures without an opening. However, the typical building structures usually have four-sided fixed walls having an opening. Therefore, it may induce a considerable error when dynamic responses are estimated based on the conventional SDOF system, since the SDOF system cannot consider the effect of an opening during the SDOF analysis. For this reason, this study proposes a new SDOF system to consider the effect of an opening by adjusting its load-mass factor. The load-mass factor can be modified based on the assumption that the behaviors of the four-sided fixed wall with an opening is very similar to the behaviors of the same size wall without an opening, when the uniformly distributed blast loaded area is identical. In order to confirm a feasibility of the proposed SDOF system, a series of numerical simulations were carried out for the four-sided fixed reinforced concrete (RC) wall under a blast load. The dynamic responses estimated from the proposed SDOF system and the conventional SDOF system were compared with the dynamic responses evaluated from the finite element (FE) analysis. Especially, for the maximum dynamic responses except for 50% opening case, the proposed SDOF system had about 1.1% to 25.7% normalized errors while the conventional SDOF system had about 4.1% to 49.1% normalized errors.

Evaluation of Nonlinear Response for Moment Resisting Reinforced Concrete Frames Based on Equivalent SDOF System (등가 1 자유도계에 의한 철근콘크리트 모멘트 골조구조의 비선형 지진응답 평가법의 검토)

  • 송호산;전대한
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.7 no.1
    • /
    • pp.9-16
    • /
    • 2003
  • To evaluate the seismic performance of multistory building structures use an equivalent SDOF model to represent the resistance of the structure to deformation as it respond in its predominant mode. This paper presents a method of converting a MDOF system into an equivalent SDOF model. The principal objective of this investigation is to evaluate appropriateness of converting method through perform nonlinear time history analysis of a multistory building structures and an equivalent SDOF model. The hysteresis rules to be used an equivalent SDOF model is obtained from the pushover analysis. Comparing the peak inelastic response of a moment resisting reinforced concrete frames and an equivalent SDOF model, the adequacy and the validity of the converting method is verified. The conclusion of this study is following; A method of converting a MDOF system into an equivalent SDOF model through the nonlinear time history response analysis is valid. The representative lateral displacement of a moment resisting reinforced concrete frames is close to the height of the first modal participation vector \ulcorner$_1{\beta}$${_1{\mu}}=1$. It can be found that the hysteresis rule of an equivalent SDOF model have influence on the time history response. Therefore, it necessary for selecting hysteresis rules to consider hysteresis characteristics of a moment resisting reinforced concrete frames.

A Review on Practical Use of Simple Analysis Method based on SDOF Model for the Stiffened Plate Structures subjected to Blast Loads (폭발하중을 받는 보강판 구조물의 간이 해석법에 대한 실용성 검토)

  • Kim, Ul-Nyeon;Ha, Simsik
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.57 no.2
    • /
    • pp.70-79
    • /
    • 2020
  • The offshore installation units may be subjected to various accidental loads such as collision from supply vessels, impact from dropped objects, blast load from gas explosion and thermal load from fire. This paper deals with the design and strength evaluation method of the stiffened plate structures in response to a blast load caused by a gas explosion accident. It is a comprehensive review of various items used in actual project such as the size and type of the explosive loads, general design procedure/concept and analysis method. The structural analyses using simple analysis methods based on SDOF model and nonlinear finite element analysis are applied to the particular FPSO project. Also validation studies on the design guidance given by simple analysis method based on SDOF model have also considered several items such as backpressure effects, material behavior and duration time of the overpressure. A good correlation between the prediction made by simple analysis method based on SDOF model and nonlinear finite element analysis can be generally obtained up to the elastic limit.

Comparative Study on Seismic Performance of Viscously Damped Self-Centering SDOF Systems with Elasto-Plastic SDOF Systems (점성 감쇠기를 가진 셀프 센터링 단자유도 시스템과 탄소성거동의 단자유도 시스템의 내진성능 비교에 관한 연구)

  • Kim, Hyung-Joon
    • Journal of Korean Society of Steel Construction
    • /
    • v.22 no.6
    • /
    • pp.553-561
    • /
    • 2010
  • The purpose of this paper is to analytically find the approximate supplement damping ratio of the viscous damper installed in self-centering (SC) single-degree-of-freedom (SDOF) systems with maximum displacements that are similar to those of elasto-plastic (EP) SDOF systems. The behavior of an SC SDOF system under harmonic cyclic loading was first described. Then an analytical model that can capture the behavior of the viscously damped SC SDOF system was introduced. Analysis parameters that characterize the hysteresis of the EP and SC SDOF systems were chosen, and nonlinear time-history analyses were performed using 20 historical accelerograms. Most of the SC SDOF systems with viscous dampers with approximately 10-15% damping ratios presented mean maximum displacement values that were similar to those of the EP SDOF systems. To investigate in detail the seismic performance of both systems, three EP SDOF systems and six corresponding SC SDOF systems were selected. The analyses showed that all the SC SDOF systems eliminated the residual displacements after the end of their shaking, and that the SC SDOF systems with 15% damping ratios performed better than the EP SDOF systems in terms of maximum displacement and acceleration response.