scholarly journals Long-Term Deflection of Prestressed Concrete Bridge Considering Nonuniform Shrinkage and Crack Propagation by Equivalent Load Approach

2020 ◽  
Vol 10 (21) ◽  
pp. 7754
Author(s):  
Fiseha Nega Birhane ◽  
Sung-Il Kim ◽  
Seung Yup Jang
Keyword(s):  
Prestressed Concrete ◽  
Three Dimensional ◽  
Simplified Approach ◽  
Long Span Bridges ◽  
Long Span ◽  
Dimensional Finite Element ◽  
Current Design ◽  
Equivalent Load ◽  
Three Dimensional Finite Element

Long-span prestressed concrete (PSC) bridges often suffer excessive deflection during their service lives. The nonuniform shrinkage strains of concrete caused by uneven moisture distributions can induce significant additional deflections, when combined with the creep and cracking of the concrete. Current design practices usually overlook these factors, and the few proposed approaches to consider them are complex and computationally expensive. This study proposes a simplified approach for considering the effect of nonuniform shrinkage by using the equivalent load concept in combination with a nonlinear analysis of the creep and cracking using three-dimensional finite element models. The long-term deflections of short-, medium-, and long-span PSC bridges are calculated under the combined effects of creep, shrinkage, and cracking. The results show that the nonuniform shrinkage effect is significant in medium- to long-span bridges, and that the cracking of the concrete reduces the stiffness, thereby increasing the long-term deflection of the bridges (more severely so in combination with creep and shrinkage). The predicted long-term deflections reasonably agree with the measured data. Thus, the equivalent load approach is effective for calculating long-term deflections considering nonuniform shrinkage strains, without the complicated and expensive coupling of moisture transport and structural analyses.

scholarly journals First-passage probability of the deflection of a cable-stayed bridge under long-term site-specific traffic loading

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668727 ◽  
Author(s):  
Naiwei Lu ◽  
Mohammad Noori ◽  
Yang Liu
Keyword(s):  
Heavy Traffic ◽  
First Passage ◽  
Computational Framework ◽  
Traffic Loading ◽  
Long Span Bridges ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Traffic Growth ◽  
First Passage Probability

Long-span bridges suffer from higher traffic loads and the simultaneous presence of multiple vehicles, which in conjunction with the steady traffic growth may pose a threat to the bridge safety. This study presents a methodology for first-passage probability evaluation of long-span bridges subject to stochastic heavy traffic loading. Initially, the stochastic heavy traffic loading was simulated based on long-term weigh-in-motion measurements of a highway bridge in China. A computational framework was presented integrating Rice’s level-crossing theory and the first-passage criterion. The effectiveness of the computational framework was demonstrated through a case study of a cable-stayed bridge. Numerical results show that the upper tail fitting of the up-crossing rate is an appropriate description of probability characteristics of the extreme traffic load effects of long-span bridges. The average daily truck traffic growth increases the probability of exceedance due to an intensive heavy traffic flow and results in a higher first-passage probability, but this increased trend is weakening as the continuous increase of the traffic volume. Since the sustained growth of gross vehicle weight has a constant impact on the probability of failure, setting a reasonable threshold overload ratio is an effective scheme as a traffic management to ensure the bridge serviceability.

Latent Defects in a 24-Year Old Waste-to-Energy Facility: Fact or Fiction? Pinellas County Case Study

2008 ◽  
Author(s):  
Paul J. Stoller ◽  
Anthony LoRe ◽  
William Crellin ◽  
Robert Hauser
Keyword(s):  
Waste To Energy ◽  
Procurement Process ◽  
Term Operation ◽  
Pinellas County ◽  
Preliminary Results ◽  
Latent Defects ◽  
Operation And Maintenance ◽  
Energy Facility

This paper presents the preliminary results of one of the key financial liability issues raised by the operating companies during the competitive procurement process for the long-term operation and maintenance of the 24-year old Pinellas County 3,000 tpd waste-to-energy facility.

scholarly journals A METHOD FOR THE EXTRACTION OF LONG-TERM DEFORMATION CHARACTERISTICS OF LONG-SPAN HIGH-SPEED RAILWAY BRIDGES USING HIGH-RESOLUTION SAR IMAGES

2016 ◽  
Vol XLI-B7 ◽  
pp. 35-38
Author(s):  
H. G. Jia ◽  
L. Y. Liu
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Control Point ◽  
Deformation Monitoring ◽  
Structural Deformation ◽  
Sar Images ◽  
High Speed Railway ◽  
Long Span Bridges ◽  
Long Span

Natural causes and high-speed train load will result in the structural deformation of long-span bridges, which greatly influence the safety operation of high-speed railway. Hence it is necessary to conduct the deformation monitoring and regular status assessment for long-span bridges. However for some traditional surveying technique, e.g. control-point-based surveying techniques, a lot of human and material resources are needed to perform the long-term monitoring for the whole bridge. In this study we detected the long-term bridge deformation time-series by persistent scatterer interferometric synthetic aperture radar (PSInSAR) technique using the high-resolution SAR images and external digital elevation model. A test area in Nanjing city in China is chosen and TerraSAR-X images and Tandem-X for this area have been used. There is the Dashengguan bridge in high speed railway in this area as study object to evaluate this method. Experiment results indicate that the proposed method can effectively extract the long-term deformation of long-span high-speed railway bridge with higher accuracy.

Long-term extreme buffeting response of long-span bridges considering uncertain turbulence parameters

2021 ◽  
Author(s):  
Tor Martin Lystad ◽  
Aksel Fenerci ◽  
Ole Øiseth
Keyword(s):  
Short Term ◽  
Long Span Bridges ◽  
Buffeting Response ◽  
Long Span ◽  
Long Span Bridge ◽  
Extreme Response ◽  
Current Design ◽  
Extreme Responses ◽  
Turbulence Parameters

<p>Long-term extreme response analyses are recognized as the most accurate way to predict the extreme responses of marine structures excited by stochastic environmental loading. In wind engineering for long-span bridges this approach has not become the standard method to estimate the extreme responses. Instead, the design value is often estimated as the expected extreme response from a short-term storm described by an N-year return period mean wind velocity.</p><p>In this study, the long-term extreme buffeting response of a long-span bridge is investigated, and the uncertainty of the turbulent wind field is described by a probabilistic model. The results indicate that the current design practice may introduce significant uncertainty to the buffeting load effects used in design, when the variability in the turbulence parameters as well as the uncertainty of the short-term extreme response is neglected.</p>

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