• Wind and Structures
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• v.7 no.1
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• pp.55-70
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• 2004

Aerostatic instability of a suspension bridge may suddenly appears when the deformed shape of the structure produces an increase in the value of the three components of displacement-dependent wind loads distributed in the structure. This paper investigates the aerostatic stability of suspension bridges using an advanced nonlinear method based on the concept of limit point instability. Particular attention is devoted to aerostatic stability analysis of symmetrical suspension bridges. A long-span symmetrical suspension bridge (Hu Men Bridge) with a main span of 888 m is chosen for analysis. It is found that the initial configuration (symmetry or asymmetry) may affect the instability configuration of structure. A finite element software for the nonlinear aerostatic stability analysis of cable-supported bridges (NASAB) is presented and discussed. The aerostatic failure mechanism of suspension bridges is also explained by tracing aerostatic instability path.

• 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.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.24-29
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• 2015

Bridge construction cost estimates have generally been conducted by using historial unit-price(per meter or square meter). The traditional estimating method based on unit-price references can never completely reflect the specialty of cable supported bridge. In this paper, we have developed the system for supporting the approximate construction cost and the quantity estimation based on 3D model information in the pre-project planning phase of 3-span continuous suspension bridge with 2-pylons. First of all, we'd analyzed the design information (such as structural design report, blueprint and quantity) and the real cost data from the existing suspension bridges and derived the design variables of the bridges. We developed the BIM wizard that generates a suspension bridge model parametrically based on derived design variables. The principle material quantities of suspension bridge are calculated directly from 3-dimensional bridge model built by using the BIM wizard. We have established the system that the construction cost can be estimated more specific than the traditional estimating method.

• Steel and Composite Structures
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• v.32 no.2
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• pp.189-198
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• 2019

This paper aims to study the mechanical performance of three-tower four-span suspension bridges with steel truss girders, including the static and dynamic characteristics of the bridge system, and more importantly, the influence of structural parameters including the side-main span ratio, sag-to-span ratio and the girder stiffness on key mechanical indices. For this purpose, 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 taken as an example in this study. This will be the first three-tower suspension bridge with steel truss girders in the world. The mechanical performance study and parametric analysis are conducted based on a validated three-dimensional spatial truss finite element model established for the Oujiang River North Estuary Bridge using MIDAS Civil. It is found that a relatively small side-main span ratio seems to be quite appropriate from the perspective of mechanical performance. And decreasing the sag-to-span ratio is an effective way to reduce the horizontal force subjected to the midtower and improve the antiskid safety of the main cable, while the vertical stiffness of the bridge will be reduced. However, the girder stiffness is shown to be of minimal significance on the mechanical performance. The findings from this paper can be used for design of three-tower suspension bridges with steel truss girders.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.551-556
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• 2007

In this paper, the contents of numerical in the innovative tender design of the super long-span suspension bridge to be constructed between Myodo and are introduced. The total span length of the bridge, of which the main span is the third in the world so far, reaches 2,260km, and the has the floating type girder which has no vertical points at pylon. Judging from the condition of navigation, wind climate on, and construction cost, it is inevitable to make the central span 1,545m and to the technical level applied to the structural components in the existing suspension system. To realize the innovative super long-span suspension bridge, the close numerical investigations for the structural capacity, aerodynamic serviceability, and dynamic serviceability are carried out by various tools of computational mechanics.

• Wind and Structures
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• v.5 no.5
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• pp.407-422
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• 2002

Passive control of the flutter condition of suspension bridges using a combined vertical and torsional tuned mass damper (TMD) system is presented. The proposed TMD system has two degrees of freedom, which are tuned close to the frequencies corresponding to vertical and torsional symmetric modes of the bridge which get coupled during flutter. The bridge-TMD system is analyzed for finding critical wind speed for flutter using a finite element approach. Thomas Suspension Bridge is analyzed as an illustrative example. The effectiveness of the TMD system in increasing the critical flutter speed of the bridge is investigated through a parametric study. The results of the parametric study led to the optimization of some important parameters such as mass ratio, TMD damping ratio, tuning frequency, and number of TMD systems which provide maximum critical flutter wind speed of the suspension bridge.

• Wind and Structures
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• v.14 no.3
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• pp.187-208
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• 2011

Based on the ANSYS, an approach of full-mode aerodynamic flutter analysis for long-span suspension bridges has been presented in this paper, in which the nonlinearities of structure, aerostatic and aerodynamic force due to the deformation under the static wind loading are fully considered. Aerostatic analysis is conducted to predict the equilibrium position of a bridge structure in the beginning, and then flutter analysis of such a deformed bridge structure is performed. A corresponding computer program is developed and used to predict the critical flutter wind velocity and the corresponding flutter frequency of a long-span suspension bridge with double main span. A time-domain analysis of the bridge is also carried out to verify the frequency-domain computational results and the effectiveness of the approach proposed in this paper. Then, the nonlinear effects on aerodynamic behaviors due to aerostatic action are discussed in detail. Finally, the results are compared with those of traditional suspension bridges with single main span. The results show that the aerostatic action has an important influence on the flutter stability of long-span suspension bridges. As for a suspension bridge with double main spans, the flutter mode is the first anti-symmetrical torsional vibration mode, which is also the first torsional vibration mode in natural mode list. Furthermore, a double main-span suspension bridge is better in structural dynamic and aerodynamic performances than a corresponding single main-span structure with the same bridging capacity.

• PNF and Movement
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• v.18 no.3
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• pp.315-321
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• 2020

Purpose: Recent studies have indicated that applying different inclination angles and suspension devices could be a useful way of performing exercises that include the co-activation of the trunk muscles. Present study was to examine the influences of changes in the inclination angle during trunk muscle activity while engaging in a bridge exercise with a suspension device. Methods: 18 healthy, physically active male volunteers completed three trunk inclination angles (15°, 30°, and 45°) for bridge exercise variations. The surface electromyography responses of the rectus abdominis, internal oblique (IO), erector spinae (ES), and rectus femoris (RF), as well as the subjective difficulty (Borg RPE score), were investigated during these bridge exercises. Results: The bridge with a 45° inclination angle suspension significantly increased the muscular activities of the RA and RF and increased the Borg RPE scores (p<0.05). The bridge with a 15° suspension significantly elevated the ES activities when compared to the other conditions. Conclusion: The present study demonstrated that a higher inclination angle could not activate the overall trunk muscles during the bridge exercise. The RA and RF produced greater activation during the bridge exercise with the higher inclination angle. On the other hand, the activities of the erector spine were greater during the bridge exercise with the lower inclination angle. The present study suggests that applying a low trunk inclination angle for the supine bridge exercise is suitable for activating the erector spine muscles.

• Structural Engineering and Mechanics
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• v.50 no.2
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• pp.215-229
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• 2014

Due to the lack of effective longitudinal constraint for center tower, structural stiffness of three-tower suspension bridge becomes less than that of two-tower suspension bridge, and therefore it becomes more susceptible to the seismic action. By taking a three-tower suspension bridge-the Taizhou Highway Bridge over the Yangtze River with two main spans of 1080 m as example, structural dynamic characteristics and seismic performance of the bridge is investigated, and the effects of cable's sag to span ratio, structural stiffness of the center tower, and longitudinal constraint of the girder on seismic response of the bridge are also investigated, and the favorable structural system is discussed with respect to seismic performance. The results show that structural response under lateral seismic action is more remarkable, especially for the side towers, and therefore more attentions should be paid to the lateral seismic performance and also the side towers. Large cable's sag, flexible center tower and the longitudinal elastic cable between the center tower and the girder are favorable to improve structural seismic performance of long-span three-tower suspension bridges.

• Wind and Structures
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• v.9 no.4
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• pp.331-344
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• 2006

The cable-stayed-suspension hybrid bridge is a cooperative system developed from the traditional cable-stayed and suspension bridges, and takes some advantages of the two bridge systems. It is also becoming a competitive design alternative for some long and super long-span bridges. But due to its great flexibility, the flutter stability plays an important role in the design and construction of this bridge system. Considering the geometric nonlinearity of bridge structures and the effects of nonlinear wind-structure interaction, method and its solution procedure of three-dimensional nonlinear flutter stability analysis are firstly presented. Parametric analyses on the flutter stability of a cable-stayed-suspension hybrid bridge with main span of 1400 meters are then conducted by nonlinear flutter stability analysis, some design parameters that significantly influence the flutter stability are pointed out, and the favorable structural system of the bridge is also discussed based on the wind stability.