Main Pylon Research Articles

Quantifying site-response effect of spatial variability earthquake on seismic failure mode of long-span sea-crossing cable-stayed bridges

Long-span cable-stayed bridge is a prevalent bridge type for sea-crossing passages and occupies an essential role in the transportation system. Non-uniform excitations significantly impact the response of long-span cable-stayed bridges, especially the site-response effect (ESR), which is one of the three primary characteristics. This paper employs a long-span sea-crossing cable-stayed bridge with consideration of hydrodynamic and pile-soil effects to systematically study the influence regularity and parameter sensitivity of the site parameter ωc on the response of critical components, and develop probabilistic seismic demand models between each component and ωc. The results reveal that the fragility of each component exhibits dissimilar sensitivities related to ωc, specifically, the changing amplitude of bearing fragility is greater than that of the bridge pylon. Consequently, when the soil type at the pylons changes from soft to solid, the damage sequence of the main pylon, pier and bearing has been changed, which exhibits different damage mechanism and failure mode. Furthermore, the mathematical model between the seismic parameters and damage mechanism is established to quantify the impact of ESR on the failure mode of sea-crossing cable-stayed bridges. Thus, it could provide a theoretical basis for the earthquake damage assessment and seismic optimization of long-span cable-stayed bridges.

Geometry control of special-shaped arch pylon considering seasonal temperature changes during construction

Structures requiring long construction periods often experience significant temperature changes, which lead to a deviation of the completed alignment from the expectation, even to the failure of construction and usage in some cases. This paper introduces the main pylon of the cable-stayed bridge on the Yong-ding river, a steel box arch pylon assembled on temporary brackets. Further, a rapid modeling method is also proposed for steel box structures. Considering the contact between the main pylon and brackets, the geometry control is analyzed based on a pre-set deformation. After that, the change of temperature during the construction is presented and decomposed, and the control alignment of the pylon is recalculated based on seasonal and random temperatures. The results show that: The elements are strictly activated in the tangent mode only if the birth and death element method is coupled with the rectification of the stress-free state. The effect of temperature change in the construction is realized by taking into account the stress-free state of the structure. In the main pylon of the Yong-ding river, the seasonal temperature change leads to maximum variances of 7 cm and 4 cm along and across the bridge, respectively. Random temperature has a likelihood of less than 0.4% that the closing port's deviation exceeds the permissible value of 1/4000. For large and complex structures that experience different seasons, the influence of seasonal temperature changes on structure (alignment) cannot be ignored.

Study on dynamic characteristics and seismic response of the extradosed cable-stayed bridge with single pylon and single cable plane

Taking Sifang Bridge in Suijiang County, Yunnan Province as a research object, this paper established a three-dimensional finite-element model of the entire bridge. In the semi-floating structure system, the dynamic characteristics were calculated according to the pile–soil interaction, and the influence of pile–soil interaction on the dynamic characteristics of the structure was analyzed. Based on this, the seismic dynamic time history analysis method was used by considering the cable sag, nonlinearity of the support, rigidity of the structure, boundary condition setting, and the pile–soil interaction. Then, we analyzed the seismic performance of the structure and its responses by providing the seismic wave at different levels. The results showed that the structure can be softened by the pile–soil interaction. The dynamic characteristics of the structure in each direction could be accurately reflected by considering the pile–soil interaction. Due to the weak lateral stiffness of the main pylon, the other structural measures should be added in the design. The support between the pylon and girder was the most unfavorable part in the along bridge segment, while the bottom of the pylon was the most unfavorable part in the across bridge segment. Under the earthquake magnitude E1, the bridge sustained the damage and the structure was in the elastic working range. Under the earthquake magnitude E2, some local repairable damage has been detected in some segment of the bridge. The results of this study can be used as a potential reference for practical engineering problems as well as can provide the parameter basis for the subsequent seismic design of the bridge. At the same time, this study has also provided a theoretical reference and an effective method for the seismic analysis of cable-stayed bridge with single pylon and single cable plane of the same kind.

Optimization of Stay Cables in the Double-Set Arch Pylon Cable-Stayed Bridge

The determination of post-tensioning cable forces is one of the most important issues for the design of arch pylon cable stayed bridge. In this paper, the optimization module implemented in MATLB, together with the commercial finite element software MIDAS, were employed to evaluate the minimum bending strain energy of the bridge. After optimizing the cable forces, the bending moment of the pylons were bigger than the values of original design. The bending moment of the main arch pylon within 55m to 70m height increased by 7280 kN•m, and the bending moment of the auxiliary arch pylon within 30m to 60m height increased by 3926 kN•m .The stress of the pylons was still far below the allowance value when the obtained cable forces were applied. However, for the girder, the difference between the maximum positive and maximum negative bending moments due to dead load can be lessened greatly by the application of the obtained cable forces. The results obtained revealed that the method presented could make full use of cable forces and lead to optimal structural performance.

Research on Design and Construction of Main Pylon of Maanshan Changjiang River Highway Bridge

The subject investigated of this article is Maanshan Changjiang River Highway Bridge, which is a prestressed concrete cable-stayed bridge with three arched pylons. With the analysis of the details in design and construction of the main pylon of bridge, such as the set of the beams, the design of curve-shaped pylon and some significant parameters, it provide feasible experience in multi-pylon cable-stayed bridge. This article established the simplified finite element model with the software MIDAS/Civil and analyzed the load carrying capability and the deformation at the finished state of the bridge.

Full-Scale Model Test for Anchorage Zone of Pylon of Cable-Stayed Bridge

In this paper, the construction technology for main pylon of cable-stayed bridge is researched through test of full-scale model of anchorage zone of pylon of Guangzhou Bridge. Stress distribution and deformation condition of model under prestressed tendons and cable force are analyzed. Numerical simulation on this anchorage zone model is carried out. By comparing FEM results to the test results, some important conclusions are drawn out and give some advices to the optimum design of the bridge pylon. Parts of the achievements have been applied to actual bridge work and obtained successful engineering experience.

Analysis of Cable-Stayed Bridge for APDL-Based Optimization

Optimum design for a cable-stayed bridge structure is very complicated because of large number of design variables. Use of ANSYS parametric design language in optimizing such structure consumes little computational time. The finished dead state analysis for single pylon double cable plane cable-stayed bridge with 120m long is performed. Mechanics equivalent are developed for the main pylon with concrete-filled steel tube. Prestress girder finite element model is established also. The theory of minimum bending strain energy is used in deriving the objective function as the quadratic form of the post-tensioning cable forces. In addition, the maximum deflection of the pylon and the maximum stresses of the main girder are both implemented in the optimization model. Optimized cable forces are found by optimization. Calculated results show that after the optimization, the cable force slightly changes, yet the internal force state under dead load remarkably improves, the bending stress of girder as well as the deflection of pylon significantly decreases. All these variations are satisfied for the limit value of engineering code. The results obtained revealed that the method presented indeed leads to optimal structural performance for the cable-stayed bridge in particular, and might be a useful reference for the design of other similar bridges.

Airborne multi-axis DOAS measurements of atmospheric trace gases on CARIBIC long-distance flights

Abstract. A DOAS (Differential Optical Absorption Spectroscopy) instrument was implemented and operated onboard a long-distance passenger aircraft within the framework of the CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container). The instrument was designed to keep weight, size and power consumption low and to comply with civil aviation regulations. It records spectra of scattered light from three viewing directions (nadir, 10° above and below horizon) using a miniaturized telescope system. The telescopes are integrated in the main pylon of the inlet system which is mounted at the belly of the aircraft. Fibre bundles transmit light from the telescopes to spectrograph-detector units inside the DOAS container instrument. The latter is part of the removable CARIBIC instrument container, which is installed monthly on the aircraft for a series of measurement flights. During 30 flight operations within three years, measurements of HCHO, HONO, NO2, BrO, O3 and the oxygen dimer O4 were conducted. All of these trace gases except BrO could be analysed with a 30 s time resolution. HONO was detected for the first time in a deep convective cloud over central Asia, while BrO, NO2 and O3 could be observed in tropopause fold regions. Biomass burning signatures over South America could be seen and measurements during ascent and descent provided information on boundary layer trace gas profiles (e.g. NO2 or HCHO).

Aesthetic Design of Haneda Sky Arch

The Haneda Sky Arch, located in front of the new passenger terminal of Tokyo International Airport (Haneda Airport), consists of a pair of steelcable-stayed girder superstructures supported by a main arch pylon. In the construction of the new terminal, two design concepts were given priority, recognizability and architectural harmony. To help achieve such a goal, this unique arch bridge was designed to become the symbol for the newly enlarged airport. The three-dimensional arrangement of the cables lends an elegant grace to the Sky Arch when viewed from various vantage points, and its unique structural form makes it readily identifiable. The Sky Arch integrates numerous interesting features, including (a) slender main girder superstructures that suggest the lines of an airplane's wing, (b) interesting stainless steel details, (c) smooth cold-worked curves on arch rib corners, and (d) field-welded splices to minimize the use of mechanical fasteners. These features are in complete harmony with the architect...

Aesthetic Design of Haneda Sky Arch

The Haneda Sky Arch, located in front of the new passenger terminal of Tokyo International Airport (Haneda Airport), consists of a pair of steel-cable-stayed girder superstructures supported by a main arch pylon. In the construction of the new terminal, two design concepts were given priority, recognizability and architectural harmony. To help achieve such a goal, this unique arch bridge was designed to become the symbol for the newly enlarged airport. The three-dimensional arrangement of the cables lends an elegant grace to the Sky Arch when viewed from various vantage points, and its unique structural form makes it readily identifiable. The Sky Arch integrates numerous interesting features, including (a) slender main girder superstructures that suggest the lines of an airplane's wing, (b) interesting stainless steel details, (c) smooth cold-worked curves on arch rib corners, and (d) field-welded splices to minimize the use of mechanical fasteners. These features are in complete harmony with the architecture of the other facilities. Fulfilling both functional and decorative purposes, the remarkable design of the Haneda Sky Arch enhances the overall attractiveness of the new airport facilities.

Optimum Design System for Steel Cable-Stayed Bridges Dealing with Shape, Sizing Variables and Cable Prestresses

: A general-purpose, rigorous and efficient optimum design system for steel cable-stayed bridges is developed, in which not only can the cable anchor positions on the main girder and pylon, and the crosssectional dimensions of the member elements be dealt with as design variables, but also the pseudo-loads applied to the cables. A powerful two-stage optimum design method is proposed to determine the optimum values of design variables for the cost minimization problem under stress constraints. At the first-stage optimization process, the cable arrangement and sizing variables are optimized by using the approximate concept and dual method with mixed direct/inverse design variables. Then the optimum values of pseudoloads, which induce the optimum prestresses into the cables, and the optimum sizing variables are determined so as to minimize the total cost of the bridge further by utilizing the sensitivities with respect to the pseudo-loads and a modified linear programming algorithm. The rigorousness, eficiency and practical usefulness of the proposed optimum design system are demonstrated by giving numerical design examples and the investigations of the optimum solutions at various design conditions. The significances of dealing with cable anchor positions and pseudo-loads as design variables are also emphasized.