Review on the Impact of Elements Used During Bridge Construction

The requirement of long span bridge is increase with development of infrastructure facility in every nation. Long span bridge could be achieved with use of high strength materials and innovative techniques for analysis of bridge. Generally, cable-supported bridges comprise both suspension and cable-stayed bridges. Cable-supported bridges are very flexible in behavior. These flexible systems are susceptible to the dynamic effects of wind and earthquake loads. The cable-stayed bridge could provide more rigidity due to the presence of tensed cable stays as a force resistance element.

SHM System and a FEM Model-Based Force Analysis Assessment in Stay Cables

The Rędziński Bridge in Wrocław is the biggest Polish concrete cable-stayed bridge. It is equipped with a large structural health monitoring (SHM) system which has been collecting the measured data since the bridge opening in the year 2011. This paper presents a comparison between the measured data and the finite element method (FEM) calculations, while taking into account 7 years of data collection and analyses. The first part of this paper concerns the SHM application. In the next part, which contains comparisons between forces in cables and temperature changes throughout the structure, the measured data are presented. The third part includes SHM-based calculations and simulations with a complex FEM model to check the measured data and to estimate future measurements. The last part contains a durability assessment calculation for the cable stays.

Replacement of Cable Stays in Yonghe Bridge in Tianjin, China

Cable replacement is one of the most important approaches for retrofitting an existing cable-stayed bridge. The Yonghe Bridge opened to traffic in 1987 and was the largest concrete cable-stayed bridge in Asia at the time. After nearly 20 years in service, its stay-cable system was completely replaced. The present paper details the key technical points of cable replacement in this bridge, including causes of replacement, cable replacement design, construction monitoring during replacement, and cable tension tuning after replacement. Based on the measurements during construction, the variation in structural condition indexes was thoroughly investigated, such as cable forces throughout the bridge, geometry profile of bridge deck, and tower horizontal displacements. The structural changes due to cable replacement were evaluated, and then, a relatively desirable scheme of cable adjustment was correspondingly put forward. The measured results showed that, influenced by the accumulated tolerances of cable forces during construction, cable replacement may often lead to a further deviation of structural condition. In this instance, cable adjustment is an effective compensation measure to improve the overall structural condition of the bridge. The practice of cable replacement in the Yonghe Bridge has provided some valuable experience or beneficial references for the similar retrofitting cases.

ALAMILLO BRIDGE: CONSTRUCTION SIMULATION MODELS IN EZSTROBE

The Puente del Alamillo in Seville, Spain, designed by Santiago Calatrava, has a single pylon that rises at an angle away from the deck, and which together with the deck resembles a harp whose strings are the cable stays from the pylon to the deck. It is the only bridge of its kind in the world whose pylon is not back-anchored, and its deck and pylon balance at a single massive footing below the pylon. This design made construction of the bridge very risky because the unfinished bridge had to be kept in balance like a giant teeter-totter until it could rest at the secondary support away from the pylon. A total of three construction plans were investigated by the contractor with the first two rejected and the third used for construction. Previous research presented simulation models for these three plans in CYCLONE along with construction time estimates for the bridge deck and pylon. Unfortunately, the published simulation models had mistakes that led to incorrect statistical results and conclusions. This paper describes these mistakes and presents three simulation models in EZStrobe that produce appropriate statistics and conclusions. These models can be used as practical examples for the application of discrete-event simulation to construction.

Unfinished Business (1863–69)

returned to Cincinnati in 1863 to find his two solitary bridge towers ready to receive the complex system of suspension cables, supporting beams, cable stays, and trusses he had designed. The work of completing the bridge took a further year and half, during which his wife Johanna passed away, a fact that led John to dabble for almost a year in séances. Fortunately, John’s triumph over the Ohio came just as New York was clamoring for someone to bridge the East River. It didn’t take long for the board of trustees to offer John a contract. Over the next two years, John worked feverishly at his drawing board. Unfortunately, the task would prove harder than even the most ardent sceptic had imagined, and John himself would not live to see it done. On June 28, 1869, John’s right foot was crushed by a ferry as he surveyed the Brooklyn waterfront, and he contracted lockjaw. He died in agony several weeks later.

Experimental and Theoretical Studies of Wet Snow Accumulation on Inclined Cylindrical Surfaces

Wet snow accumulation on bridge cables and its shedding due to external phenomena such as rise in temperature, wind, and gravity is a serious threat to the safety of cars and pedestrians crossing the bridge. Commonly the accumulated snow on bridge cables is removed by external means such as mechanical removal or heat treatment which are expensive, time-consuming, and high-risk processes and are conducted based on little or no information available regarding the actual size and shape of the accumulated snow. In addition, cleaning of cables using the mechanical methods can potentially lead to erosion of cable materials when applied over years, resulting in enhanced surface roughness and potentially increased wet snow/ice accumulation during future precipitation events, and sometimes might require replacement of cable stays, which is an extremely costly and complicated task. Optimizing the number of mechanical cleaning procedures such as chain release through predicting the shape and thickness of the accumulated snow on the cable stays reduces the cost, time, and risk associated with the process. In this study, wet snow accumulation on torsionally rigid inclined cylinders of high-density polyethylene (HDPE) has been studied experimentally and numerically. A 2-D numerical model has been developed utilizing weather data to predict the thickness and the shape of the accumulated wet snow on inclined cylindrical surfaces. Outdoor experiments were also conducted to measure the density and thickness of accumulated snow, while monitoring the weather data real time. Overall, snow density was found to be linearly increasing with an increase in wind velocity, during snow precipitation. The maximum thickness and shape of the accumulated snow on cables obtained from the numerical model were found to be in good agreement with the outdoor experimental data. This work aims to provide a mean for prediction of snow accumulation on surfaces for optimizing the efficiency of the costly and high-risk snow removal procedures.

Monitoring, analysis and durability assessment of a concrete cable-stayed bridge

<p>Over the last 20 years big bridges in Poland have been built and equipped in Structural Health Monitoring systems (SHM). One of those objects is the Rędziński Bridge in Wrocław. It is a cable-stayed concrete bridge built along the motorway A8 in 2011. Since this time the SHM has been collecting data from 222 installed sensors. The bridge is outstanding because of its unusual structure: two separate concert box girders are suspended to a single pylon. The connection is made of 160 stay cables – so this is also the most sensitive part of the structure.</p><p>The first part of the paper concerns the SHM application. In the next part the measured data form the period 2011-2017 are presented, containing comparisons between forces in cables and temperature changes in the whole structure. The third part will include SHM based calculations and simulations with a complex FEM model, to check the measured data and to estimate future measurements. The last part contains the durability assessment calculation for the cable stays.</p>

Specifics of determining the tension forces of the cable-stayed bridge elements

Objective: to improve the method of determining the force in the cable stays by frequencies of natural transverse oscillations. Methods: synthesis and analysis of theoretical and experimental data, experimental methods for studying the structures. Results: in the paper, the problems of determining the tension forces of the cable stays by the frequencies of their natural oscillations are considered taking into account various factors (the design of anchor fastenings, the angle of inclination and sagging of the cable stay, the change of temperature). The estimation of possible errors in calculations is given. The degree of coincidence of the actual and design stress-strain state of the cable stays depends on the correctness of accounting the influence of the factors considered. The effect of the temperature change and the anchor fastening structure on the frequency of the natural oscillations of the cable stays has been experimentally tested. The recommendations on the determination of the forces in the cable stays by dynamic parameters are given. A method for controlling the tension forces of the cable stays and specialized software “Vant” (“Cable”) for automation of the measurement process are developed. The method has been tested on several bridge structures that have cable-stayed elements. Practical significance: the ability to use the developed method for controlling the tension forces of cable-stayed elements during the operation of artificial structures.