Parsing on the Processing Methods of Seamline for Concrete Bridgewith Seamless Broaden Technology

In view of the difference in design, construction and the usage of the old and the new bridges, there are always stress defects in seamline because of the concrete creep and shrinkage, temperature effect and prestress loss, which seriously affect the service and driving safety. The current ways in foreign and domestic, such as plant steel and semi-rigid connection method, are passive processing based on structure, can’t ensure the long-term performance. According to the three direction stress existing in the seamline, this paper decomposes the material contribution and structure influence, putting forward respectively using material and structure to overcome the adverse situation, using material to remove partial long-term effect, and through the sensitivity analysis of related parameters, to make the structure bearing the rest adverse effect, ensuring the long-term performance of seamline. The relevant conclusion can provide reference for the design and construction of the concrete bridge seamline.

Download Full-text

Literature Reviews and Summary of Concrete Bridge Seamless Broaden Technology

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.193-194.1290 ◽

2012 ◽

Vol 193-194 ◽

pp. 1290-1295 ◽

Cited By ~ 3

Author(s):

Fang Yuan Li ◽

Zheng Yuan Xie ◽

Xiao Shuai Guo

Keyword(s):

Concrete Bridge ◽

Prestress Loss ◽

Shrinkage Temperature ◽

Literature Reviews ◽

Rigid Connection ◽

Long Term Performance ◽

Term Performance ◽

Creep And Shrinkage ◽

Design Construction

When the bridges broaden with seamless technology, there are differences between the existing bridge and the new bridge in design, construction and service. Because of concrete creep and shrinkage, temperature effect and prestress loss, there are stress defects in the seam, which will affect the service and safety. The current methods for the seam in foreign and domestic, such as plant steel and semi-rigid connection method are passive measures based on structure exiting state, which cannot ensure the long-term performance of the seam.

Download Full-text

Analysis of Long-Term Prestress Loss in Prestressed Concrete (PC) Structures Using Fiber Bragg Grating (FBG) Sensor-Embedded PC Strands

Applied Sciences ◽

10.3390/app112412153 ◽

2021 ◽

Vol 11 (24) ◽

pp. 12153

Author(s):

Sung-Tae Kim ◽

Young-Soo Park ◽

Chul-Hwan Yoo ◽

Soobong Shin ◽

Young-Hwan Park

Keyword(s):

Optical Fiber ◽

Prestressed Concrete ◽

Optical Fiber Sensor ◽

Fiber Sensor ◽

Prestress Loss ◽

Fbg Sensor ◽

Embedded Pc ◽

Long Term Performance ◽

Term Performance

This study aims to develop a prestressed concrete steel (PC) strand with an embedded optical Fiber Bragg Grating (FBG) sensor, which has been developed by the Korea Institute of Civil Engineering and Building Technology since 2013. This new strand is manufactured by replacing the steel core of the normal PC strand with a carbon-fiber-reinforced polymer (CFRP) rod with excellent tensile strength and durability. Because this new strand is manufactured using the pultrusion method, which is a composite material manufacturing process, with an optical fiber sensor embedded in the inner center of the CFRP Rod, it ensures full composite action as well as proper function of the sensor. In this study, a creep test for maintaining a constant load and a relaxation test for maintaining a constant displacement were performed on the proposed sensor-type PC strand. Each of the two tests was conducted for more than 1000 h, and the long-term performance verification of the sensor-type PC strand was only completed by comparing the performance with that of a normal PC strand. The test specimens were fabricated by applying an optical fiber sensor-embedded PC strand, which had undergone long-term performance verification tests, to a reinforced concrete beam. Depending on whether grout was injected in the duct, the specimens were classified into composite and non-composite specimens. A hydraulic jack was used to prestress the fabricated beam specimens, and the long-term change in the prestress force was observed for more than 1600 days using the embedded optical fiber sensor. The experimental results were compared with the analytical results to determine the long-term prestress loss obtained through finite-element analysis based on various international standards.

Download Full-text

The Relations between QFII Holdings and Company Performance: Evidence from China’s A-Share Listed Companies

Discrete Dynamics in Nature and Society ◽

10.1155/2014/821463 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Xiong Wang ◽

Shuanghong Zhou ◽

Wenqian Fang

Keyword(s):

Listed Companies ◽

Company Performance ◽

Company Value ◽

Long Run ◽

Long Term Effect ◽

Report Data ◽

Long Term Performance ◽

Term Performance ◽

A Share

In order to investigate the relations between qualified foreign institutional investors (QFII) holdings and the performance of the A-share listed companies and effectively distinguish between QFIIs’ ability to identify value companies and their ability to enhance company value, this paper empirically examines the relations between QFII holdings and company performance using Chinese annual report data from 2010 to 2012. The results show that QFIIs have strong ability in identifying value companies. However, the effect of QFII holdings on company performance improvement is mainly manifested in the short term, and the long-term effect is insignificant. In the long run, QFIIs may not be considered as “value boosters,” implying that it is unlikely for QFIIs to greatly enhance company value and help the invested companies to improve the level of governance and their long-term performance.

Download Full-text

Long-Term Performance Evaluation of Main Cable for Large Span Suspension Bridge Based on ARIMA Model

10.3233/atde210174 ◽

2021 ◽

Author(s):

Shiqiao Xu ◽

Rujin Ma ◽

Chuanjie Cui

Keyword(s):

Time Series ◽

Performance Evaluation ◽

Arima Model ◽

Engineering Research ◽

Large Span ◽

Main Cable ◽

The Difference ◽

Long Term Performance ◽

Term Performance

Main cables are major load-bearing components and play a decisive role in the long-term performance of suspension bridges. In particular, the wide application of health monitoring systems in large-span bridges facilitates a new channel for the performance evaluation of bridges. Under this context, Xihoumen Bridge is taken as the engineering research background. The long-term performance of the bridge’s main cable was evaluated by analyzing the main cable strand force data from January 2015 to October 2020, which was collected by the anchor rope meter. Firstly, the difference calculation was performed on the basis of the modeling theory of stationary time series to realize the stationary process of the original time series. Then, the Autoregressive Integrated Moving Average (ARIMA) model is established to predict the main cable strand force of the Xihoumen Bridge by model order estimation and parameter identification. Finally, the load degree index is defined in the discussion part to evaluate the long-term performance and determine the performance grading of the main cable.

Download Full-text

Enhancement of a UASB-septic tank performance for decentralised treatment of strong domestic sewage

Water Science & Technology ◽

10.2166/wst.2011.690 ◽

2011 ◽

Vol 64 (4) ◽

pp. 923-929 ◽

Cited By ~ 5

Author(s):

Nidal Mahmoud ◽

Jules B. van Lier

Keyword(s):

Domestic Sewage ◽

Cod Removal ◽

Septic Tank ◽

Anaerobic Sludge ◽

Reactor Performance ◽

Removal Efficiencies ◽

The Difference ◽

Long Term Performance ◽

Term Performance

The possibility of enhancing the process performance of the UASB-septic tank for treating strong sewage in Palestine by means of inoculating the reactor with well adapted anaerobic sludge and/or adding a packing media to the upper part of the reactor, creating an anaerobic hybrid (AH)-septic tank, was investigated. To achieve these objectives, two community onsite UASB-septic tank and AH-septic tank were operated in parallel at 2 days HRT for around 8 months overlapping the cold and hot periods of the year in Palestine. The achieved removal efficiencies of CODtot in the UASB-septic tank and AH-septic tank during the first months of operation, coinciding with the cold period and the subsequent hot period, were respectively 50(±15)% and 48(±15)% and 66(±8)% and 55(±8)%. This shows that the UASB-septic tank performed significantly better (p < 0.05) than the AH-septic tank after rather long periods of operation. The difference in the CODtot removal efficiency was mainly due to the better CODss removal efficiencies in the UASB-septic tank. The removal efficiencies over the last 50 days of operation for CODtot, CODsus, CODcol and CODdis were 70, 72, 77 and 55% and 53, 54, 78 and 45% for the UASB-septic tank and AH-septic tank, respectively. Comparing the here achieved COD removal efficiencies with previously reported efficiencies of UASB-septic tanks operated in Palestine shows that the reactor performance in terms of COD removal and conversion, during the first 8 months of operation, has improved substantially by being started with well adapted anaerobic sludge, simulating and predicting long-term performance. Adding packing media did not lead to an improvement.

Download Full-text