Reliability Assessment for the Balanced Cantilever Construction Phases of Super Long-Span Cable-Stayed Bridges with Steel Box Girder

2014 ◽  
Vol 578-579 ◽  
pp. 1542-1550 ◽  
Author(s):  
Bing Bai ◽  
Qing Hua Zhang ◽  
Qiao Li
Keyword(s):  
Reliability Evaluation ◽  
Long Span ◽  
Stay Cables ◽  
Sample Structure ◽  
Sutong Bridge ◽  
The Stability ◽  
High Level ◽  
Cantilever Construction ◽  
Random Nature ◽  
Cable Stayed Bridges

Balanced cantilever construction phases are of great importance for the total life cycle processes of super long-span cable-stayed bridges. For assessment purpose, a systematic study on the reliability evaluation of these phases is carried out. Taking Sutong bridge as the sample structure studied, a series of load and resistance models are then established on the basis of field measurement. Using all these achievements, a typical phase of girder segment 6# lifting is chosen for reliability evaluation. Results of the analysis show that the established models are quite representative and reflect actual random nature perfectly. Furthermore, compared with pylon and stay cables the stiffening girder seems more likely to fail in accordance with reliability index. The major failure mode of it in terms of present analysis is the stability failure due to the action of bending and axial load. Nonetheless, the components on the whole are still in a high level of reliability, which can guarantee the proceeding of construction with efficiency.

scholarly journals Serviceability Assessment Method of Stay Cables with Vibration Control Using First-Passage Probability

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Seunghoo Jeong ◽  
Young-Joo Lee ◽  
Sung-Han Sim
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
Principal Component ◽  
Assessment Method ◽  
Stay Cable ◽  
First Passage ◽  
Long Span Bridges ◽  
Long Span ◽  
Stay Cables ◽  
Cable Stayed Bridges

As the construction of long-span bridges such as cable-stayed bridges increases worldwide, maintaining bridge serviceability and operability has become an important issue in civil engineering. The stay cable is a principal component of cable-stayed bridges and is generally lightly damped and intrinsically vulnerable to vibration. Excessive vibrations in stay cables can potentially cause long-term fatigue accumulation and serviceability issues. Previous studies have mainly focused on the mitigation of cable vibration within an acceptable operational level, while little attention has been paid to the quantitative assessment of serviceability enhancement provided by vibration control. This study accordingly proposed and evaluated a serviceability assessment method for stay cables equipped with vibration control. Cable serviceability failure was defined according to the range of acceptable cable responses provided in most bridge design codes. The cable serviceability failure probability was then determined by means of the first-passage problem using VanMarcke’s approximation. The proposed approach effectively allows the probability of serviceability failure to be calculated depending on the properties of any installed vibration control method. To demonstrate the proposed method, the stay cables of the Second Jindo Bridge in South Korea were evaluated and the analysis results accurately reflected cable behavior during a known wind event and show that the appropriate selection of vibration control method and properties can effectively reduce the probability of serviceability failure.

scholarly journals Probabilistic Assessment Approach of the Aerostatic Instability of Long-Span Symmetry Cable-Stayed Bridges

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2413
Author(s):  
Fenghui Dong ◽  
Feng Shi ◽  
Libin Wang ◽  
Yang Wei ◽  
Kaiqi Zheng
Keyword(s):  
Finite Element ◽  
Safety Factor ◽  
Random Variables ◽  
Safety Analysis ◽  
Safety Factors ◽  
Long Span ◽  
Reliability Method ◽  
Sutong Bridge ◽  
Cable Stayed Bridges ◽  
Probabilistic Safety

The existing safety analysis methods for the assessment of the aerostatic stability of long-span symmetry cable-stayed bridges have difficulties in meeting the requirements of engineering applications. Based on the finite element method and the inverse reliability theory, an approach for the probabilistic safety analysis of the aerostatic instability of long-span symmetry cable-stayed bridges is proposed here. The probabilistic safety factor of aerostatic instability of long-span symmetry cable-stayed bridges was estimated using the proposed method, with Sutong Bridge as an example. The probabilistic safety factors for the aerostatic instability of Sutong Bridge were calculated using the finite element inverse reliability method, based on the FORM approach. The influences of the mean value and the coefficient of variation of random variables, as well as the iterative step length of finite difference, on the probabilistic safety factors of aerostatic instability of Sutong Bridge were analyzed. The results indicated that it is necessary to consider the uncertainties of random variables in probabilistic safety factor assessments of aerostatic instability in cable-stayed bridges using the proposed method, which could be recommended for the assessment of safety factors involved in the aerostatic instability of long-span symmetry cable-stayed bridges. The randomness of the parameters had an important influence on the probabilistic safety factor of the aerostatic stability of Sutong Bridge. Neglecting the randomness of these parameters may result in instability of the structure.

Main span closure for the New Samuel de Champlain Bridge (NSCB) - An innovative alternative closure using a temporary king-post to accelerate construction

2019 ◽  
Author(s):  
Gonzalo Osborne ◽  
Frederic Saleh
Keyword(s):  
Stay Cable ◽  
Project Completion ◽  
Long Span ◽  
Stay Cables ◽  
The Subject ◽  
Construction Schedule ◽  
Lifting Equipment ◽  
Main Bridge ◽  
Cable Stayed Bridges ◽  
Schedule Requirement

<p>Signature Saint Laurent (SSLC) is the consortium comprised of SNC Lavalin, Flatiron Constructors Canada, Dragados USA and EBC, that selected the design and construction for the New Samuel de Champlain Bridge (NSCB) in Montreal, Canada.</p><p>The NSCB’s construction schedule was the major challenge for a successful project completion. The geometry of the main bridge is complex, with an asymmetric stay cable arrangement and a unique transverse behavior with three independent corridors connected by crossbeams, involving the location of the stay cable anchorages. This geometry questioned the constructability and the stringent schedule requirement. The subject of this paper is relevant to this conference as it pertains to an innovative construction method for cable-stayed bridges.</p><p>The back span was fully erected on temporary towers in advance, followed by the main span which was to be built with heavy lifting equipment in cantilever sequentially from the main single pylon towards to the East approach. A set of three gantries erected the preassembled segments from the ground to the tip of the deck, where they were connected to the previous segment.</p><p>To expedite the construction, an innovative method was developed to erect some segments from the opposite end with cranes from the ground, with a stick-built conventional method. The closure location was therefore shifted by 50 meters (four segments) towards the pylon. These segments would be supported with temporary stay cables anchored to a 36-meter high king-post on top of the deck. The king-post would be sitting on top of the deck, supported temporarily by shoring towers to reduce the demands in the superstructure and adjacent pier.</p><p>This erection system can serve as an alternative method to expedite construction for long span single tower cable stayed bridges, by erecting segments with a temporary stay tower from the opposite end, therefore reducing schedule constraints.</p>

Structural Design of Experimental Study on Rain-Wind-Induced Vibration of Strayed Cables

2012 ◽  
Vol 532-533 ◽  
pp. 412-416
Author(s):  
Wei Li ◽  
Wei Guo ◽  
Hua Bai
Keyword(s):  
Aerodynamic Characteristics ◽  
Wind Pressure ◽  
3 Dimensional ◽  
Pressure Coefficients ◽  
Long Span ◽  
Stay Cables ◽  
Safe Production ◽  
Wind Induced Vibration ◽  
Fluctuating Wind ◽  
Cable Stayed Bridges

To study the aerodynamic characteristics of strayed cable under wind and rain, with the object of the Zhijiang bridge, pressure experiments on the 2- and 3-dimensional models of stay cables in wind tunnel are made. Mean and fluctuating wind-pressure coefficients with 2 kinds of surface morphology under different wind direction angle are obtained. The results show that the rivulet position will greatly influence the distribution of pressure coefficients on the cable surface, and the separation point of the flow nearby the rivulet will be changed obviously. Aerodynamic coefficients will be changed when the rivulet be in a certain position, then the rain-wind-induced vibration will occur .The experimental results will be the guidance for the wind-resistant design and the safe production of the long-span cable-stayed bridges.

System reliability evaluation of long-span cable-stayed bridges

2010 ◽  
Vol 97 (28) ◽  
pp. 57-63
Author(s):  
Jin Cheng ◽  
Xiao-luan Liu ◽  
Ru-cheng Xiao
Keyword(s):  
System Reliability ◽  
Reliability Evaluation ◽  
Long Span ◽  
Cable Stayed Bridges

scholarly journals Automated Real-Time Assessment of Stay-Cable Serviceability Using Smart Sensors

2019 ◽  
Vol 9 (20) ◽  
pp. 4469 ◽  
Author(s):  
Seunghoo Jeong ◽  
Young-Joo Lee ◽  
Do Hyoung Shin ◽  
Sung-Han Sim
Keyword(s):  
Real Time ◽  
Damping Ratio ◽  
Assessment System ◽  
Smart Sensors ◽  
Stay Cable ◽  
Long Span Bridges ◽  
Long Span ◽  
Stay Cables ◽  
High Flexibility ◽  
Cable Stayed Bridges

The number of cable-stayed bridges being built worldwide has been increasing owing to the increasing demand for long-span bridges. As the stay-cable is one of critical load-carrying members of cable-stayed bridges, its maintenance has become a significant issue. The stay-cable has an inherently low damping ratio with high flexibility, which makes it vulnerable to vibrations owing to wind, rain, and traffic. Excessive vibration of the stay-cable can cause long-term fatigue problems in the stay-cable as well as the cable-stayed bridge. Therefore, civil engineers are required to carry out maintenance measures on stay-cables as a high priority. For the maintenance of the stay-cables, an automated real-time serviceability assessment system using wireless smart sensors was developed in this study. When the displacement of the cable in the mid-span exceeds either the upper or the lower bound provided in most bridge design codes, it is considered as a serviceability failure. The system developed in this study features embedded on-board processing, including the measurement of acceleration, estimation of displacement from measured acceleration, serviceability assessment, and monitoring through wireless communication. A series of laboratory tests were carried out to verify the performance of the developed system.

Feasibility of Using a Negative Stiffness Damper to Two Interconnected Stay Cables for Damping Enhancement

2019 ◽  
Vol 19 (06) ◽  
pp. 1950058 ◽  
Author(s):  
Peng Zhou ◽  
Min Liu ◽  
Huigang Xiao ◽  
Hui Li
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Responses ◽  
Negative Stiffness ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Stay Cables ◽  
Modal Damping ◽  
Vibration Responses ◽  
White Noises ◽  
Cable Stayed Bridges

The dynamic behavior of stay cables has a significant impact on the safety and serviceability of cable-stayed bridges. As tuning such dynamic behavior could be effectively achieved by a damping increase on stay cables, this paper investigates on the feasibility of increasing damping on two stay cables simultaneously through interconnecting them with a negative stiffness damper (NSD). It presents the passive realization of the NSD through the following process. First, under harmonic excitations, the steady-state dynamic responses of the two cables in the network are derived. Then, the asymptotic solutions for the additional modal damping ratios are formulated with the critical viscous damping and negative stiffness determined approximately. Subsequently, a parametric analysis is performed to verify the theoretical derivations using two stay cables of a real long-span cable-stayed bridge, under a series of numerical evaluations consisting of sinusoidal excitations and white noises vibrational responses for both cables. Both the theoretical and numerical results show superior damping enhancement by the NSD, in that the vibration responses of the two cables are reduced remarkably.

Radiation Effects on Hollandite Ceramics developed for Radioactive Cesium Immobilization

2003 ◽  
Vol 792 ◽  
Author(s):  
V. Aubin ◽  
D. Caurant ◽  
D. Gourier ◽  
N. Baffier ◽  
S. Esnouf ◽  
...  
Keyword(s):  
Radiation Effects ◽  
Liquid Waste ◽  
Fission Products ◽  
Radioactive Cesium ◽  
Radioactive Liquid Waste ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Γ Radiation ◽  
The Stability ◽  
High Level

ABSTRACTProgress on separating the long-lived fission products from the high level radioactive liquid waste (HLW) has led to the development of specific host matrices, notably for the immobilization of cesium. Hollandite (nominally BaAl2Ti6O16), one of the main phases constituting Synroc, receives renewed interest as specific Cs-host wasteform. The radioactive cesium isotopes consist of short-lived Cs and Cs of high activities and Cs with long lifetime, all decaying according to Cs+→Ba2++e- (β) + γ. Therefore, Cs-host forms must be both heat and (β,γ)-radiation resistant. The purpose of this study is to estimate the stability of single phase hollandite under external β and γ radiation, simulating the decay of Cs. A hollandite ceramic of simple composition (Ba1.16Al2.32Ti5.68O16) was essentially irradiated by 1 and 2.5 MeV electrons with different fluences to simulate the β particles emitted by cesium. The generation of point defects was then followed by Electron Paramagnetic Resonance (EPR). All these electron irradiations generated defects of the same nature (oxygen centers and Ti3+ ions) but in different proportions varying with electron energy and fluence. The annealing of irradiated samples lead to the disappearance of the latter defects but gave rise to two other types of defects (aggregates of light elements and titanyl ions). It is necessary to heat at relatively high temperature (T=800°C) to recover an EPR spectrum similar to that of the pristine material. The stability of hollandite phase under radioactive cesium irradiation during the waste storage is discussed.

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