• Title, Summary, Keyword: multi-span suspension bridge

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Study on economic performances of multi-span suspension bridges part 2: parametric study

  • Zhang, Li-Wen;Xiao, Ru-Cheng;Sun, Bin;Jiang, Yang;Zhang, Xue-Yi;Zhuang, Dong-Li;Zhou, Yun-Gang;Tu, Xue
    • Structural Engineering and Mechanics
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    • v.47 no.2
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    • pp.287-305
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    • 2013
  • Economic performances of consecutive multi-span suspension bridges are studied. The material amount and cost estimation formulas of the bridges have been derived in the part 1 of the study. A parametric study is carried out based on the formulas for investigating the different factors' effect on the bridge cost. The factors include the bridge sag, the bridge span, the bridge foundation and the environment condition, etc. Then, an economical layout of the bridges is proposed for different conditions. Lastly, a selection of suspension bridge types is discussed based on the economy of bridges.

Study on midtower longitudinal stiffness of three-tower four-span suspension bridges with steel truss girders

  • Cheng, Jin;Xu, Hang;Xu, Mingsai
    • Structural Engineering and Mechanics
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    • v.73 no.6
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    • pp.641-649
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    • 2020
  • The determination of midtower longitudinal stiffness has become an essential component in the preliminary design of multi-tower suspension bridges. For a specific multi-tower suspension bridge, the midtower longitudinal stiffness must be controlled within a certain range to meet the requirements of sliding resistance coefficient and deflection-to-span ratio. This study presents a numerical method to divide different types of midtower and determine rational range of longitudinal stiffness for rigid midtower. In this method, influence curves of midtower longitudinal stiffness on sliding resistance coefficient and maximum vertical deflection-to-span ratio are first obtained from the finite element analysis. Then, different types of midtower are divided based on the regression analysis of influence curves. Finally, rational range for longitudinal stiffness of rigid midtower is derived. The Oujiang River North Estuary Bridge which is a three-tower four-span suspension bridge with two main spans of 800m under construction in China is selected as the subject of this study. This will be the first three-tower four-span suspension bridge with steel truss girders and concrete midtower in the world. The proposed method provides an effective and feasible tool for engineers to design midtower of multi-tower suspension bridges.

Equivalent Suspension Bridge Model for Tower Design of Multi-span Suspension Bridges (다경간 현수교 주탑 설계를 위한 등가 현수교 모델)

  • Choi, Dong-Ho;Na, Ho-Sung;Yi, Ji-Yop;Gwon, Sun-Gil
    • Journal of Korean Society of Steel Construction
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    • v.23 no.6
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    • pp.669-677
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    • 2011
  • The multi-span suspension bridge generally has more than three towers and two main spans. To economically and effectively design a multi-span suspension bridge, the proper stiffness ratio of the center tower to the side tower must be determined. This study was conducted to propose a method of figuring out briefly the structural behavior of the towers in a multi-span suspension bridge. In the equivalent suspension bridge model, the main cable of the multi-span suspension bridge is idealized as an equivalent cable spring, and the external loads of horizontal and vertical forces that were calculated using the tensile forces of the main cable were applied on top of the towers. The equilibrium equations of the equivalent multi-span suspension bridge model were derived and the equations were solved via nonlinear analysis. To verify the proposed method, a sample four-span suspension bridge with a main span length of 3,000 m was analyzed using thefinite element method. The displacements and moment reactions of each tower in the proposed method were compared with the FEM analysis results. Consequently, the results of the analysis of the equivalent suspension bridge model tended to be consistent with the results of the FEM analysis.

Study on economic performances of multi-span suspension bridges part 1: simple estimation formulas

  • Zhang, Li-Wen;Xiao, Ru-Cheng;Sun, Bin;Jiang, Yang;Zhang, Xue-Yi;Zhuang, Dong-Li;Zhou, Yun-Gang;Tu, Xue
    • Structural Engineering and Mechanics
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    • v.47 no.2
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    • pp.265-286
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    • 2013
  • A study on economic performances of consecutive multi-span suspension bridges is carried out. In this part of the study, material amount and structural cost estimation formulas of the bridges is derived based on the structural ultimate carrying capacity. The bridge cost includes the part of superstructure and the part of substructure. Three types of bridge foundations, bored piles, concrete caissons and floating foundations, are considered in substructure. These formulas are to be used for the parametric study of the bridge cost in order to define its more economical layout under different conditions in the part two of the study.

Initial Equilibrium State Analysis of Cable Members for Preliminary Analysis of Multi-span Suspension Bridge under Dead Load (고정하중을 받는 다경간 현수교의 예비해석을 위한 케이블 부재의 초기평형상태 해석)

  • Choi, Dong-Ho;Na, Ho-Sung;Gwon, Sun-Gil
    • Journal of The Korean Society of Civil Engineers
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    • v.36 no.1
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    • pp.21-29
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    • 2016
  • This paper proposes a method to determine the initial equilibrium state of cable members for preliminary analysis of multi-span suspension bridge under dead load. The proposed method is simpler and more practical than the previous methods used in other studies. The proposed method can be applied to three-span or multi-span suspension bridges. To verify the proposed method, an three-span model as well as four-span models such as New Millenium Bridge in Korea and Yingwuzhou Bridge in China are analyzed. In the verification results, the initial coordinates and tensions of the members calculated by the proposed method are good agreement with those in the previous study for the three-span model and those in the design data of New Millenium Bridge. In addition, the proposed method gives the initial values to keep the initial configuration of Yingwuzhou Bridge.

The characteristics of the multi-span suspension bridge with double main cables in the vertical plane

  • Zhang, Li-Wen;Xiao, Ru-Cheng;Jiang, Yang;Chai, Sheng-Bo
    • Structural Engineering and Mechanics
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    • v.42 no.3
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    • pp.291-311
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    • 2012
  • The multi-span suspension bridge having double main cables in the vertical plane is investigated regarding endurance of live load distribution in the case of non-displaced pylon and pylon displacement. The coefficient formula of live load distribution described as the ratio of live load on the bottom cable to the top cable is obtained. Based on this formula, some function in respect of this bridge are derived and used to analyze its characteristics. This analysis targets the cable force, the cable sag and the horizontal displacement at the pylon top under live load etc. The results clarified that the performance of the live load distribution and the horizontal force of cables in the case of non-deformed pylon has a similar tendency to those in the case of deformed pylon, and the increase of pylon rigidity can increase live load distributed to the bottom cable and slightly raise the cable horizontal force under live load. However, effect on the vertical rigidity of bridge and the horizontal force increment of cables caused by live load is different in the case of non-deformed pylon and deformed pylon.

Optimal variables of TMDs for multi-mode buffeting control of long-span bridges

  • Chen, S.R.;Cai, C.S.;Gu, M.;Chang, C.C.
    • Wind and Structures
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    • v.6 no.5
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    • pp.387-402
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    • 2003
  • In the past decades, much effort has been made towards the study of single-mode-based vibration controls with dynamic energy absorbers such as single or multiple Tuned Mass Dampers(TMDs). With the increase of bridge span length and the tendency of the bridge cross-section being more slender and streamlined, multi-mode coupled vibrations as well as their controls have become very important for large bridges susceptible to strong winds. As a simple but effective device, the TMD system especially the semi-active one has become a promising option for such coupled vibration controls. However, despite various studies of optimal controls of single-mode-based vibrations with TMDs, research on the corresponding controls of the multi-mode coupled vibrations is very rare so far. For the development of a semi-active control strategy to suppress the multi-mode coupled vibrations, a comprehensive parametric analysis on the optimal variables of this control is substantial. In the present study, a multi-mode control strategy named "three-row" TMD system is discussed and the general numerical equations are developed at first. Then a parametric study on the optimal control variables for the "three-row" TMD system is conducted for a prototype Humen Suspension Bridge, through which some useful information and a better understanding of the optimal control variables to suppress the coupled vibrations are obtained. This information lays a foundation for the design of semi-active control.

Effects of Flexural Rigidity of Center Tower in Four-Span Suspension Bridges (4경간 현수교에서의 중앙주탑 휨강성의 영향)

  • Gwon, Sun-Gil;Yoo, Hoon;Choi, Dong-Ho
    • Journal of The Korean Society of Civil Engineers
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    • v.34 no.1
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    • pp.49-60
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    • 2014
  • For simple and accurate analysis for behaviors of multi-span suspension bridges which are expected to be frequently constructed as strait-crossing bridges, the deflection theory as the peculiar theory of a suspension bridge can be applied. This paper performs a structural analysis for four-span suspension bridges using the deflection theory. Simply-supported beams with tension are used for girders and the deflections of the beams due to the vertical loads and moments at supports are calculated. The calculation is performed iteratively until the deflections satisfy the compatibility equations of cables. The results of the deflection theory analysis considering tower rigidity are compared with those of the finite element analysis for verification. Importance of the tower rigidity for four-span suspension bridges is confirmed using various compatibility equations of the cable due to variation of the constraint conditions between main cable and top of towers. In addition, the simple parametric analysis for variation of the center tower rigidity is performed.

Suppression of aerodynamic response of suspension bridges during erection and after completion by using tuned mass dampers

  • Boonyapinyo, Virote;Aksorn, Adul;Lukkunaprasit, Panitan
    • Wind and Structures
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    • v.10 no.1
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    • pp.1-22
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    • 2007
  • The suppression of aerodynamic response of long-span suspension bridges during erection and after completion by using single TMD and multi TMD is presented in this paper. An advanced finite-element-based aerodynamic model that can be used to analyze both flutter instability and buffeting response in the time domain is also proposed. The frequency-dependent flutter derivatives are transferred into a time-dependent rational function, through which the coupling effects of three-dimensional aerodynamic motions under gusty winds can be accurately considered. The modal damping of a structure-TMD system is analyzed by the state-space approach. The numerical examples are performed on the Akashi Kaikyo Bridge with a main span of 1990 m. The bridge is idealized by a three-dimensional finite-element model consisting of 681 nodes. The results show that when the wind velocity is low, about 20 m/s, the multi TMD type 1 (the vertical and horizontal TMD with 1% mass ratio in each direction together with the torsional TMD with ratio of 1% mass moment of inertia) can significantly reduce the buffeting response in vertical, horizontal and torsional directions by 8.6-13%. When the wind velocity increases to 40 m/s, the control efficiency of a multi TMD in reducing the torsional buffeting response increases greatly to 28%. However, its control efficiency in the vertical and horizontal directions reduces. The results also indicate that the critical wind velocity for flutter instability during erection is significantly lower than that of the completed bridge. By pylon-to-midspan configuration, the minimum critical wind velocity of 57.70 m/s occurs at stage of 85% deck completion.