scholarly journals Effect of Construction Method on Shear Lag in Prestressed Concrete Box Girders

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Shi-Jun Zhou
Keyword(s):  
Cross Sections ◽  
Prestressed Concrete ◽  
Construction Process ◽  
Shear Lag ◽  
Box Girders ◽  
Box Girder ◽  
Construction Methods ◽  
Concrete Box Girder ◽  
Concrete Box Girder Bridges ◽  
Girder Bridge

Most of the previous researches conducted on shear lag of box girders were only concerned about simple types of structures, such as simply supported and cantilever beams. The structural systems concerned in these previous researches were considered as determined and unchangeable. In this paper, a finite element method considering shear lag and creep of concrete was presented to analyze the effect of dynamic construction process on shear lag in different types of concrete box-girder bridges. The shear lag effect of the three types of a two-span continuous concrete beam classified by construction methods was analyzed in detail according to construction process. Also, a three-span prestressed concrete box-girder bridge was analyzed according to the actual construction process. The shear lag coefficients and stresses on cross sections along the beam including shear lag were obtained. The different construction methods, the changes of structural system with the construction process, the changes of loading and boundary conditions with the construction process and time, the prestressing, and creep were all imitated in the calculations. From comparisons between the results for beams using different construction methods, useful conclusions were made.

scholarly journals Load Distribution In Adjacent Precast "Deck Free" Concrete Box-Girder Bridges

2021 ◽  
Author(s):  
Waqar Khan
Keyword(s):  
Prestressed Concrete ◽  
Precast Concrete ◽  
Box Girders ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Concrete Box Girder ◽  
Concrete Box Girder Bridges ◽  
Girder Bridge ◽  
The Moment

Bridges built with adjacent precast, prestressed concrete box-girders are a popular and economical solution for short-span bridges because they can be constructed rapidly. The top flanges of the precast box girders form the bridge deck surface. A shear key is introduced between the adjacent boxes over the depth of the top flange (i.e. 225 mm thick as the thickness of the box's top flange). Canadian Highway Bridge Design Code, CHBDC specifies empirical equations for the moment and shear distribution factors for selected bridge configurations but not for adjacent precast concrete box-girder bridge type. In this study, a parametric study was conducted, using the 3D finite-element modeling, and a set of simplified equations for the moment, shear and deflection distribution factors for the studied bridge configuration was developed.

scholarly journals Load Distribution In Adjacent Precast "Deck Free" Concrete Box-Girder Bridges

2021 ◽  
Author(s):  
Waqar Khan
Keyword(s):  
Prestressed Concrete ◽  
Precast Concrete ◽  
Box Girders ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Concrete Box Girder ◽  
Concrete Box Girder Bridges ◽  
Girder Bridge ◽  
The Moment

Bridges built with adjacent precast, prestressed concrete box-girders are a popular and economical solution for short-span bridges because they can be constructed rapidly. The top flanges of the precast box girders form the bridge deck surface. A shear key is introduced between the adjacent boxes over the depth of the top flange (i.e. 225 mm thick as the thickness of the box's top flange). Canadian Highway Bridge Design Code, CHBDC specifies empirical equations for the moment and shear distribution factors for selected bridge configurations but not for adjacent precast concrete box-girder bridge type. In this study, a parametric study was conducted, using the 3D finite-element modeling, and a set of simplified equations for the moment, shear and deflection distribution factors for the studied bridge configuration was developed.

Study on Crack Causes and Strengthening Measures of Large Span PC Continuous Box Girder Bridges

2010 ◽  
Vol 163-167 ◽  
pp. 3551-3554
Author(s):  
Wei Peng ◽  
Zhi Xiang Zha
Keyword(s):  
Prestressed Concrete ◽  
Load Test ◽  
Box Girder Bridges ◽  
Element Analysis ◽  
Box Girder ◽  
Girder Bridges ◽  
Long Span ◽  
Concrete Box Girder Bridges ◽  
Girder Bridge ◽  
Engineering Projects

This template Based on cracks observation and finite element analysis of real engineering projects as well as bridge load test after reinforcement, causes and types of cracks in prestressed concrete box girder bridges and treating measurements are systematically studied. The results obtained from the calculation are presented to demonstrate the effect of sensitive factors, such as arrangement of longitudinal prestressed tendons, the magnitude of vertical prestressed force, temperature gradient, etc. The results show that the arrangement of longitudinal prestressed tendons and the magnitude of vertical prestressed force take key roles in cracks control of box girder webs. Lots of treating measurements are presented in accordance with different types of cracks, some of them are applied to a reinforcement engineering of a long span pretressed concrete continuous box girder bridge with cracks. Load test after reinforcement of the bridge demonstrates the reasonability of the treating measurements. Several design recommendations and construction measures about reinforcements and some sensitive factors mentioned above are proposed to control cracks.

scholarly journals Numerical Analysis of Temperature Influence on Transverse Cracks in Concrete Box-Girder Bridges

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Hanzheng Xu ◽  
Xiaofeng Yan
Keyword(s):  
Numerical Analysis ◽  
Highway Bridges ◽  
Hydration Reaction ◽  
Box Girders ◽  
Transverse Cracks ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Concrete Box Girder ◽  
Concrete Box Girder Bridges

Concrete box-girder bridges are widely used in China. During several routine inspections of two-year-old highway bridges of this type in the China Central Plains region, we found that transverse cracks are widespread on the bottom flanges of those box girders, mainly distributed in the area of 1/4L to 3/4L of the span. Selected cracks were then monitored continuously for one year. Our results showed that there had been no change in the widths of the cracks, but their lengths had increased and new cracks had formed. Taking into consideration factors like hydration reaction, relative humidity difference, shrinkage and creep, sunlight thermal differential effect, sudden temperature change, vehicle load, and their combined efforts, we have developed spatial structural models and conducted stress analyses on the reinforced concrete and prestressed concrete box-girder bridges, respectively. Our numerical analysis results indicated that the hydration reaction is the main reason for the initial bottom flange crack and the temperature difference between the inside and the outside of the box girders caused the crack developments at the later stage.

Optimization on Closure Scheme of Multi-Span Prestressed Concrete Box-Girder Bridge

2010 ◽  
Vol 163-167 ◽  
pp. 2369-2375 ◽  
Author(s):  
Ming Yuan ◽  
Dong Huang Yan
Keyword(s):  
Stress State ◽  
Prestressed Concrete ◽  
Box Girder ◽  
Rigid Frame ◽  
Closure Scheme ◽  
Concrete Box Girder ◽  
Box Girder Bridge ◽  
Girder Bridge ◽  
Cantilever Construction ◽  
Rigid Frame Bridge

The stress state of finished bridge and service stage is influenced by various closure schemes in cantilever construction of multi-span prestressed concrete box-girder bridge. Two typical bridges—multi-span prestressed concrete continuous rigid frame bridge and girder bridge are investigated, The stress state in different closure schemes are analyzed using finite element(FE) analysis. Meanwhile, compared the healthy monitoring data, it has been found that taking the closure sequence from side span to middle span in cantilever construction of multi-span prestressed concrete box-girder bridge can lower stress of girder and pier in finished bridge stage, as well as reducing deformation of girder in service stage. Hence, the closure sequence from side span to middle span is more suitable for cantilever construction of multi-span prestressed concrete box-girder bridge.

scholarly journals Computation of Deflections for PC Box Girder Bridges with Corrugated Steel Webs considering the Effects of Shear Lag and Shear Deformation

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Wei Ji ◽  
Kui Luo ◽  
Jingwei Zhang
Keyword(s):  
Shear Deformation ◽  
Prestressed Concrete ◽  
Displacement Function ◽  
Shear Lag ◽  
Longitudinal Displacement ◽  
Box Girders ◽  
Element Analysis ◽  
Box Girder ◽  
Bridge Model ◽  
Bridge Models

Prestressed concrete (PC) girders with corrugated steel webs (CSWs) have received considerable attention in the past two decades due to their light self-weight and high prestressing efficiency. Most previous studies were focused on the static behavior of CSWs and simple beams with CSWs. The calculation of deflection is an important part in the static analysis of structures. However, very few studies have been conducted to investigate the deflection of full PC girders or bridges with CSWs and no simple formulas are available for estimating their deflection under static loads. In addition, experimental work on full-scale bridges or scale bridge models with CSWs is very limited. In this paper, a formula for calculating the deflection of PC box girders with CSWs is derived. The longitudinal displacement function of PC box girders with CSWs, which can consider the shear lag effect and shear deformation of CSWs, is first derived. Based on the longitudinal displacement function, the formula for predicting the deflection of PC box girders with CSWs is derived using the variational principle method. The accuracy of the derived formula is verified against experimental results from a scaled bridge model and the finite element analysis results. Parametric studies are also performed, and the influences of shear lag and shear deformation on the deflection of the box girder with CSWs are investigated by considering different width-to-span ratios and different girder heights. The present study provides an effective and efficient tool for determining the deflection of PC box girders with CSWs.

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