scholarly journals Quantitative Evaluation of Unfilled Grout in Tendons of Prestressed Concrete Girder Bridges by Portable 950 keV/3.95 MeV X-ray Sources

2021 ◽  
Vol 11 (12) ◽  
pp. 5525
Author(s):  
Mitsuru Uesaka ◽  
Jian Yang ◽  
Katsuhiro Dobashi ◽  
Joichi Kusano ◽  
Yuki Mitsuya ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Quantitative Evaluation ◽  
Prestressed Concrete ◽  
Quantitative Difference ◽  
Three Dimensional ◽  
Electron Linear Accelerator ◽  
X Ray ◽  
Girder Bridges ◽  
Girder Bridge ◽  
Gray Values

We have developed porTable 950 keV/3.95 MeV X-band (9.3 GHz) electron linear accelerator (LINAC)-based X-ray sources and conducted onsite prestressed concrete (PC) bridge inspection in the last 10 years. A T-shaped PC girder bridge with a thickness of 200–400 mm and a box-shaped PC girder bridge with a thickness of 200–800 mm were tested. X-ray transmission images of flaws such as thinning, fray, and disconnection caused by corrosion of PC wires and unfilled grout were observed. A three-dimensional structural analysis was performed to estimate the reduction in the yield stress of the bridge. In this study, we attempted to evaluate the unfilled grout quantitatively because it is the main flaw that results in water filling and corrosion. In the measured X-ray images, we obtained gray values, which correspond to the X-ray attenuation coefficients of filled/unfilled grouts, PC wires (steel) in a sheath, and concrete. Then, we compared the ratio of the gray values of the filled/unfilled grouts and PC wires to determine the stage of the unfilled grout. We examined this quantitative evaluation using the data obtained from a real T-shaped PC girder bridge and model samples to simulate thick box-shaped PC girder bridges. We obtained a clear quantitative difference in the ratios for unfilled and filled grouts, which coincided with our visual perception. We synthesized the experience and data and proposed a quantitative analysis for evaluating the unfilled grout for subsequent steps such as structural analysis and destructive evaluation by boring surveys.

Effect of Shear Lag on the Long-Term Performance of Long-Span PC Box Girder Bridge

2011 ◽  
Vol 255-260 ◽  
pp. 1290-1294 ◽  
Author(s):  
Yan Wei Niu
Keyword(s):  
Prestressed Concrete ◽  
Three Dimensional ◽  
3D Analysis ◽  
Shear Lag ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Long Span ◽  
Girder Bridge

The analysis and mechanism of excessive long-term deflection of long-span prestressed concrete (PC) box girder bridges is concentrated recently. However, because of the lack of computing method, three dimensional (3D) analysis of PC continuous bridge especially including long-term shear lag effect is hard to analyze. According to this, a 3D creep analysis method for long-span PC bridges is illustrated in this paper first. The shear lag analysis of loads, prestress and their combination effect is carried out respectively. Based on this, the effect of shear lag to the long-term deflection of mid-span and whole-shape of the bridge is demonstrated. At the end, the different of computing between analysis with or without considering shear lag is discussed and some suggestion is proposed.

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.

Installation Technology of Webs in the Construction of PC Box-Girder Bridge with Corrugated Steel Webs

2012 ◽  
Vol 204-208 ◽  
pp. 2209-2213 ◽  
Author(s):  
Ya Jiang Du ◽  
Bing Wen Yang ◽  
Shui Wan
Keyword(s):  
Prestressed Concrete ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Section Shape ◽  
Out Of Plane ◽  
Box Girder Bridge ◽  
Corrugated Steel Web ◽  
Girder Bridge ◽  
Installation Technology

In the construction of prestressed concrete(PC) box-girder bridge with corrugated steel webs used cast-in-place cantilever method, the key component-corrugated steel webs are fabricated in factory first and then transported to the construction site. Because of the low out-of plane stiffness, corrugated steel webs are easy to deform in the construction, which brings many difficulties for construction. The precision of installing the corrugated steel web has a direct effect on the cross-section shape of the box-girder. So it is a key step to monitor the orientation and installation of corrugated steel web during construction. Based on the experience of some PC box-girder bridges with corrugated steel webs having been built, a method to control the installation accuracy of corrugated steel webs is proposed and some quality assurance measures are introduced in order to ensure the accuracy, reliability and security of the installation of corrugated steel web. The method can be taken as a reference in the construction of this kind of bridge.

scholarly journals Evaluating Reserve Strength of Girder Bridges Due to Bridge Rail Load Shedding

2021 ◽  
Author(s):  
Yao Wang ◽  
Mirela D. Tumbeva ◽  
Ashley P. Thrall
Keyword(s):  
Prestressed Concrete ◽  
Numerical Models ◽  
Field Testing ◽  
Load Shedding ◽  
Steel Girder ◽  
Girder Bridges ◽  
Steel Girder Bridges ◽  
Girder Bridge ◽  
Prestressed Concrete Girder Bridge ◽  
Reserve Strength

This research experimentally and numerically evaluated the reserve strength of girder bridges due to bridge rail load shedding. The investigation included: (1) performing non-destructive field testing on two steel girder bridges and one prestressed concrete girder bridge, (2) developing validated finite element numerical models, and (3) performing parametric numerical investigations using the validated numerical modeling approach. Measured data indicated that intact, integral, reinforced concrete rails participate in carrying live load. Research results culminated in recommendations to evaluate the reserve strength of girder bridges due to the participation of the rail, as well as recommendations for bridge inspectors for evaluating steel girder bridges subjected to vehicular collision.

scholarly journals Fatigue Assessment of Prestressed Concrete Slab-between-Girder Bridges

2019 ◽  
Author(s):  
Eva O.L. Lantsoght ◽  
Rutger Koekkoek ◽  
Cor van der Veen ◽  
Henk Sliedrecht
Keyword(s):  
The Netherlands ◽  
Prestressed Concrete ◽  
Concrete Slab ◽  
Fatigue Loading ◽  
Punching Shear ◽  
Membrane Action ◽  
Girder Bridges ◽  
Scale Models ◽  
Girder Bridge ◽  
Compressive Membrane Action

In the Netherlands, the assessment of existing prestressed concrete slab-between-girder bridges showed that the thin, transversely prestressed slabs may be critical for static and fatigue punching when evaluated using the recently introduced Eurocodes. On the other hand, compressive membrane action increases the capacity of these slabs and changes the failure mode from bending to punching shear. To improve the assessment of the existing prestressed slab-between-girder bridges in the Netherlands, two 1:2 scale models of an existing bridge, the Van Brienenoord Bridge, were built in the laboratory and tested monotonically as well as under cycles of loading. The result of these experiments is: 1) the static strength of the decks, showing that compressive membrane action significantly enhances the punching capacity, and 2) the Wöhler curve of the decks, showing that compressive membrane action remains under fatigue loading. The experimental results can then be used for the assessment of the most critical existing slab-between-girder bridge. The outcome is that the bridge has sufficient punching capacity for static and fatigue loads, and thus that the existing slab-between-girder bridges in the Netherlands fulfil the code requirements for static and fatigue punching.

Synthesis, spectroscopic and structural analysis of a melamine copper complex

2014 ◽  
Vol 70 (a1) ◽  
pp. C1239-C1239
Author(s):  
Amani Direm ◽  
Noureddine Dadda ◽  
Wahiba Falek ◽  
Zina Boutobba ◽  
Nourredine Benali-Cherif
Keyword(s):  
Structural Analysis ◽  
Copper Complex ◽  
Structural Investigation ◽  
Three Dimensional ◽  
Building Blocks ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Supramolecular Architectures ◽  
Carboxylic Anions

Owing to its multiple sites acting as H-bonds' donors, melamine and its derivatives are considered as excellent building blocks for the construction of various crystalline supramolecular architectures based on phosphate, sulfate, chloride and carboxylic anions [1-10] on one hand and chlorometallate anions on the other hand [11-13]. In our contribution, we will discuss the synthesis, FTIR spectra and the structural investigation using the single crystal X-ray diffraction of (H2Melamine) [CuCl5]Cl, (I). The structural analysis of (I) revealed that it consists of alternating negative and positive layers running through the a-axis direction. The negative layers are built up of alternatively CuCl53- and discrete non-coordination Cl- anions, whereas the positive sheets are formed of [H2melamine2+]2 Hydrogen-bonded dimers. The N-H...N and N-H...Cl interactions are assembled to build three-dimensional H-bond patterns which insure the cohesion within the lattice (Fig. 01). A previous work showed that (I) exhibits antiferromagnetic properties [14]

The crystal and molecular structure of aqua-bis(ethylenediamine)cupric-tris(cyano)-selenocyanatodicuprate

1982 ◽  
Vol 47 (10) ◽  
pp. 2623-2632 ◽  
Author(s):  
Viktor Vrábel ◽  
Jan Lokaj ◽  
Ján Garaj ◽  
František Pavelčík
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Structural Analysis ◽  
Least Squares Method ◽  
Crystal And Molecular Structure ◽  
Three Dimensional ◽  
Monoclinic System ◽  
Space Group ◽  
X Ray ◽  
Triclinic System

The crystal structure of [Cu(H2O)(en)2][Cu2(CN)3(SeCN)] was solved by single crystal X-ray structural analysis in the triclinic system with a space group of P1 and in the monoclinic system with a space group of C2. In the triclinic system the unit cell has dimensions of a = 0.8445(3), b = 0.7903(3), c = 0.8444(3) nm, α = 119.58(2), β = 118.59(2) and γ = 93.63(3)° and, in the monoclinic system, a = 1.3331(4), b = 0.8670(2), c = 0.8267(3), β = 122.60(2)°. The structure was refined by the least squares method to final value of R = 5.5% in the triclinic system and R = 7.8% in the monoclinic system. The coordination sphere around the Cu(II) atom is square pyramidal, formed of two ethylenediamine molecules and one water molecule. The Cu(I) atoms are tetrahedrally coordinated by bridging SeCN and CN ligands to form infinite three-dimensional chains. The SeCN group is bonded to the Cu(I) atoms through the Se atom at distances of 0.2731(3) and 0.2745(3) nm.

Dry Effect of Cementitious Materials on Testing Results of X-Ray CT

2012 ◽  
Vol 450-451 ◽  
pp. 187-192 ◽  
Author(s):  
Jian De Han ◽  
Wei Sun ◽  
Gang Hua Pan
Keyword(s):  
Cement Paste ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Drying Process ◽  
X Ray ◽  
Before And After ◽  
X Ray Computed ◽  
The Mean ◽  
The Impact ◽  
Gray Values

In this study three-dimensional X-ray computed tomography (X-ray CT) is used to investigate the testing results differences of cement paste and mortar before and after drying. It can be found that the mean gray values of paste and mortar before drying are bigger than after drying, and the impact of drying on cement paste is more serious than mortar. In addition, the porosity of non-drying cement paste and mortar is 1.10% and 0.43%, while that of drying cement paste and mortar is 1.55% and 0.70%, respectively. So, the porosity of paste and mortar markedly increases after drying process. The numbers of pores of paste and mortar sharply increase after drying process in particular between 0.01mm3 and 0.1mm3. The impact of drying on smaller pores is more serious than bigger pores.

scholarly journals The Application of the Grey Neural Network in the Deflection Control of PC Rigid Frame Continuous Box Girder Bridges

2014 ◽  
Vol 8 (1) ◽  
pp. 416-419
Author(s):  
Lifeng Wang ◽  
Hongwei Jiang ◽  
Dongpo He
Keyword(s):  
Neural Network ◽  
Prestressed Concrete ◽  
Control Process ◽  
Construction Control ◽  
Box Girder Bridges ◽  
Girder Bridges ◽  
Rigid Frame ◽  
Continuous Girder Bridge ◽  
Girder Bridge ◽  
Cantilever Construction

Deflection control is the crucial procedure in construction control of cantilever prestressed concrete continuous girder bridge. This paper summarizes the advantages of Grey theory’s poor information processing and abilities of Neural Network’s self-learning and adaption, and the combinational algorithm of grey Neural Network is applied to the prestressed concrete bridge cantilever construction control process. Firstly, GM (1, 1) model and BP artificial Neural Network algorithm to predict the elevation of construction process are introduced respectively. In addition, the elevation prediction model of rigid-framed-continuous girder bridge is established. By practicing in the construction control project of LongHua Bridge, the method is testified to be feasible. The results indicate that, the combinational algorithm of Gray Neural Network to predict the construction elevation has higher reliability and accuracy which can be an effective tool of construction control for the same type bridges.

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.

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