Prestressed Concrete Cable-stayed Bridge Research Articles

Damage detection under environmental and operational effects using cointegration analysis – Application to experimental data from a cable-stayed bridge

Abstract One of the main challenges that Structural Health Monitoring (SHM) faces when transitioning from academia to real-world applications is the discernment between structural changes due to damage and normal environmental, operational and long-term effects. In this context, a strategy for early damage detection based on multivariate cointegration analysis and statistical process control is proposed. The effects of environmental and operational variations are suppressed using cointegration analysis, being the cointegrating vector estimated following the multivariate Johansen procedure. The cointegrated residuals are then used for novelty detection by means of the Hotelling T2 control chart. The proposed strategy is systematised and is applied to a large prestressed concrete cable-stayed bridge of which 3.5 years of data are available, being the stay-cable forces used as damage sensitive-features. Several damage scenarios are studied involving increasing section loss of the stay cables. The damage intensities that can be detected using the proposed methodology and the available sensory system are quantified.

Online early damage detection and localisation using multivariate data analysis: Application to a cable‐stayed bridge

An online data-based methodology for early damage detection and localisation under the effects of environmental and operational variations (EOVs) is proposed. The methodology is described in detail and implemented in a large prestressed concrete cable-stayed bridge of which 3.5 years of data are available. The effects of EOVs are suppressed by the combined application of two well-established multivariate data analysis methods: multiple linear regression and principal component analysis. Criteria for the systematic choice of the predictor variables and the number of principal components to retain are proposed. Because the bridge is new and sound, the experimental time series are corrupted with numerically simulated damage scenarios in order to evaluate the damage detection ability. It is demonstrated that the sensitivity to damage is increased when daily, 2-day, or 3-day averaged data are used instead of hourly data. The effectiveness of the proposed methodology is also demonstrated with the detection of a real, small, and temporary sensor anomaly. The implemented methodology has revealed to be robust and efficient, presenting a contribution to the transition of structural health monitoring from academia to industry.

Design of Main Bridge of Second Penang Bridge in Malaysia

The main bridge of the Second Penang Bridge in Malaysia [1-2] is a two-pylon three-span prestressed concrete cable-stayed bridge, with span arrangement of (117.5+240+117.5) m.The pylons and the main girder are monolithic. The main girder, which is 34.6m wide, adopts the ladder type concrete deck section comprising top slab, transverse diaphragms and edge beams. The pylons are H-form pylons, and the stay cables are formed of parallel strands and are arranged in fan cable planes. Each pylon column carries 18 pairs of stay cables that are anchored by the deviation saddles in the pylons and anchor blisters in the main girder. The foundations consist of large diameter bored piles, varying from 2.3m to 2.0m in diameter. An optimized design scheme is tailored for the bridge, in which the main girder has the cross-section built up by a combination of slab, diaphragm and edge beam structuresand was constructed by using the rear supported form traveler and incorporating an optimization of construction timing. The scheme resolved the problems of load-bearing capacity verification for bridge deck and the verification of main girder prestress under the heavy vehicle loads prescribed in the BS5400. Meanwhile, a meticulous calculation method was put forward for the design and analysis of the main girder, to obtain the real load bearing conditions of the main girder and the bridge deck. The diaphragms were calculated by the spatial grillage analysis method, aimed at guaranteeing the load-bearing safety of the structure.

An adaptive support vector regression method for structural system reliability assessment and its application to a cable-stayed bridge

Engineering structures are most statically indeterminate structures consisting of various types of components and their failure modes exhibit randomness under random loads. A new adaptive support vector regression method is proposed for structural system reliability assessment. Compared with traditional support vector regression, the proposed adaptive support vector regression method involves two updating procedures to estimate structural limit state functions. Three verification examples involving a nonlinear limit state function, a truss bridge structure, and a geometrically nonlinear suspended structure are provided to illustrate the accuracy and the efficiency of the adaptive support vector regression method. A pre-stressed concrete cable-stayed bridge is utilized to demonstrate the applicability of the proposed method. The verification studies show that the proposed adaptive support vector regression method is an efficient method with reasonable accuracy for problems where closed-form failure functions are not available and the failure sequences exist in the structural system. The main failure sequences of the cable-stayed bridge are identified. The application studies of the cable-stayed bridge indicate that (a) the foremost failure sequence is the strength failure of side-span cables followed by the bending failure of towers and (b) the secondary failure sequence is the strength failure of mid-span cables followed by bending failure of mid-span girders.

Stochastic Analysis of Prestressed Concrete Cable-Stayed Bridges Considering Construction Errors

There is a deviation between finished bridge and design requirement of prestressed concrete (PC) cable-stayed bridge due to the construction errors in construction process. Besides, the randomness of construction errors will cause the variability of structure system in construction state. However, the most common analyses considering construction errors are based on deterministic analysis method, which concern the mean errors effect merely. These are inadequate obviously. In this paper the main construction errors of PC cable-stayed bridge and corresponding distributions are outlined firstly. Also several common stochastic analysis methods are introduced. Using Monte-Carlo method with ANSYS finite element analysis (FEA) software, then, a stochastic analysis of a single tower PC cable-stayed bridge considering construction errors is completed, and the probability characteristics of structural response under dead load are obtained. Finally, from the reliability point of view, the influence of randomness of construction errors on structural safety and the necessity of stochastic analysis for PC cable-stayed bridges are discussed.

The effect of cable loosening on seismic response of a prestressed concrete cable-stayed bridge

In conventional non-linear seismic analyses of cable-stayed bridges, the non-linear characteristics of the girders, stay cables and towers are considered. The non-linearity caused by cable loosening should also be considered because a large axial force fluctuation is generated in the cables of a prestressed concrete (PC) cable-stayed bridge that is subjected to strong seismic motion. In this paper, the possibility of the cable loosening in a PC cable-stayed bridge is discussed by using a cable model that can express the cable loosening. Furthermore, the effect of the cable loosening on the responses of the cables, girder and towers is evaluated using the mean value for three seismic waves. Numerical analytic results imply that the cable loosening appears in the bottom cables of the multi-cable system and the dynamic response of the bridge is slightly increased.

PC斜張橋の設計技術の現状

我が国のPC斜張橋の建設実績は100橋近くにまで達し, その設計技術は大きな発展をとげている。また基準類等でも, PC斜張橋に関して取り上げられてきている。そこで本論文では, PC斜張橋の設計技術の現状を施工実績を紹介しながら, 解析手法や各構造部位ごとの設計法に分けて説明するものとした。また, PC斜張橋と同種橋りょうであるエクストラドーズドPC橋やPC斜版橋についても併せてここに報告する。

わが国最大級のPC斜張橋の施工

秩父公園橋は, 現在, 埼玉県が秩父地域の振興を図るために建設を進めている秩父ミューズパークへのアクセス道路が, 一・級河川荒川を渡河する地点に架けられる2径間連続PC斜張橋である。本橋は, 支間195m+195mを有し, 総幅員は19.0mで, 3径間に換算すれば中央スパン400mクラスに匹敵するわが国最大級のPC斜張橋である。本稿では, 本橋施工にあたり, その合理化・急速化を目的に現場で採用した種々の施工法およびそれらの改良点について報告する。

左右非対称の高橋脚PC斜張橋の設計・施工

左右非対称の高橋脚PC斜張橋の設計・施工

STRUCTURAL BEHAVIOR MONITORING AND ADJUSTING SYSTEM USED IN SUPERSTRUCTURE CONSTRUCTION OF PRESTRESSED CONCRETE CABLE-STAYED BRIDGE, YOBUKO-OHASHI BRIDGE

The Yobuko-Ohashi Bridge, located in Yobuko Town, Saga Prefecture, is a 3-span continuous prestressed concrete cable-stayed road bridge with a center span of 250m, which connects an isolated island, Kabejima Island, to Kyushu. It is the longest-span concrete bridge in Japan. In construction of the superstructure, the girders were constructed by cast-in-place balanced cantilever method using travelers. And the deflection of girders, tensile forces in stay cables and stresses in girders, which are essential for prestressed concrete cable-stayed bridges, were monitored and adjusted rationally and promptly with the help of a new system using microcomputer. This report outlines the system used in this bridge construction project.