scholarly journals Thermal stresses in rectangular concrete beams, resulting from constraints at microstructure, cross-section, and supports

2022 ◽  
pp. 104495
Author(s):  
Hui Wang ◽  
Yong Yuan ◽  
Herbert A. Mang ◽  
Qing Ai ◽  
Xingchun Huang ◽  
...  
Keyword(s):  
Cross Section ◽  
Thermal Stresses ◽  
Concrete Beams

scholarly journals The influence of reinforcement temperature on stiffness of reinforced concrete beams in fire conditions

2013 ◽  
Vol 12 (1) ◽  
pp. 115-122
Author(s):  
Michał Głowacki ◽  
Marian Abramowicz ◽  
Robert Kowalski
Keyword(s):  
High Temperature ◽  
Cross Section ◽  
Static Load ◽  
Concrete Beams ◽  
Bending Moment ◽  
Reinforced Concrete Beams ◽  
Temperature Influence ◽  
Calculation Results ◽  
Tensile Zone ◽  
In Fire

This paper describes the analysis of high temperature influence on beams with heated tensile zone. High temperature experiments were preformed under the static load of 50 or 70% of the destructive force ensuring constant value of bending moment in the central part of the heated beam. Beams with 2 reinforcement ratios – 0.44 and 1.13% were examined. In total four series of beams, three in each series (12 elements) were used. This paper analyses the reduction of relative beam cross section stiffness depending on reinforcement temperature. Experimentally obtained stiffness values calculated in two ways (element maximal deflection and deflection measured in three points of analysed element) were compared to calculation results made according to Eurocode. The performed analysis shows that reduction of the stiffness of element based on Eurocode calculations is slightly bigger than the experimentally obtained one.

Experimental Research on Mechanical Behavior of Carbon Fiber Reinforced Concrete Beam

2013 ◽  
Vol 641-642 ◽  
pp. 393-397
Author(s):  
Le Zhou ◽  
Jun Wei Wang ◽  
Hong Tao Liu
Keyword(s):  
Carbon Fiber ◽  
Cross Section ◽  
Brittle Failure ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Reinforced Concrete Beam ◽  
Fiber Reinforced Concrete ◽  
Test Model ◽  
Steel Bar ◽  
Fiber Concrete

Based on the cross-section bending of 5 carbon fiber concrete beams, the mechanism of deflection and strain of carbon fiber concrete beam were studied considering the variation of the length of carbon fiber. The experimental results show that the deflection of destruction increased with the increase of the length of the carbon fiber. The carbon fiber can effectively improve the brittle failure of concrete beam, and the stain of concrete accorded with that steel bar at the same height. According to the existing test model, the theoretical calculating formula of CFRC was proposed.

scholarly journals Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyu Fu ◽  
Dawei Tong ◽  
Yuyang Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Internal Force ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Gradual Change ◽  
Concrete Cracking ◽  
Good Agreement

Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.

Flexural capacity and design of hybrid FRP-steel-reinforced concrete beams

2019 ◽  
Vol 23 (7) ◽  
pp. 1290-1304
Author(s):  
Yang Yang ◽  
Ze-Yang Sun ◽  
Gang Wu ◽  
Da-Fu Cao ◽  
Zhi-Qin Zhang
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Steel Reinforced Concrete ◽  
Reinforced Polymer ◽  
The Cross

This study presents a design method for hybrid fiber-reinforced-polymer-steel-reinforced concrete beams by an optimized analysis of the cross section. First, the relationships among the energy consumption, the bearing capacity, and the reinforcement ratio are analyzed; then, the parameters of the cross section are determined. Comparisons between the available theoretical and experimental results show that the designed hybrid fiber-reinforced-polymer-steel-reinforced concrete beams with a low area ratio between the fiber-reinforced polymer and the steel reinforcement could meet the required carrying capacity and exhibited high ductility.

Analysis of Thermal Stratification and Fatigue Stress for Pressurizer Surge Line

2010 ◽  
Author(s):  
Xiaofei Yu ◽  
Yixiong Zhang
Keyword(s):  
Cross Section ◽  
Thermal Stratification ◽  
Thermal Stresses ◽  
Structural Integrity ◽  
Bending Moments ◽  
One Dimensional ◽  
Pipe System ◽  
Pipe Cross Section ◽  
Fatigue Stress ◽  
Surge Line

Thermal stratification of pressurizer surge line induced by the inside fluid brings on global bending moments, local thermal stresses, unexpected displacements and support loadings of the pipe system. In order to confirm the structural integrity of pressurizer surge line affected by thermal stratification, this paper theoretically establishes thermal stratified transient and studies the calculation method of thermal stratified stress. A costly three-dimensional computation is simplified into a combined 1D/2D technique. This technique uses a pipe cross-section for computation of local thermal stresses and represents the whole surge line with one-dimensional pipe elements. The 2D pipe cross-section model is used to compute elastic thermal stresses in plane strain condition. Symmetry allows half the cross-section to be considered. The one-dimensional pipe elements model gives the global bending moments including effects of usual thermal expansion and thermal stratification of each model nodes. This combined 1D/2D technique has been developed and implemented to analyze the thermal stratification and fatigue stress of pressurize surge line in this paper, using computer codes SYSTUS and ROCOCO. According to the mechanical analysis results of stratification, the maximum stress and cumulative usage factor are obtained. The stress and fatigue intensity of the surge line tallies with the correlative criterion.

Adjustment for Temperature and Deformation of Concrete Beams

2005 ◽  
Vol 297-300 ◽  
pp. 2667-2674
Author(s):  
Si Rong Zhu ◽  
Zhuo Qiu Li ◽  
Xian Hui Song
Keyword(s):  
Life Span ◽  
Temperature Difference ◽  
Thermal Effects ◽  
Thermal Stresses ◽  
Concrete Beams ◽  
Mass Concrete ◽  
The Sun ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

Cement structures such as bridges and dams often come into being distortion or exhibit excessive thermal stresses due to the sun radiation or freeze-thaw cycle. Therefore, temperature especially inner temperature difference or deformation of structures must be controlled or regulated sometimes in order to reduce thermal stresses or excessive deformation and to extend the life-span of structures. In this paper, the electro-thermal effects of smart cement are used to adjust temperature difference or deformation of concrete beams without the need of peripheral non-structural materials. Concrete beams for temperature and deformation adjustment were fabricated, and some experimental results as well as the related conclusions about temperature difference and deformation were produced. Based on these results, experiments of temperature difference or deflection adjustment are further conducted successfully. The research results in this paper are the bases of temperature and deformation adjustment for mass concrete structures. A new path will be broken to adjust temperature or deformation easily for some structures.

scholarly journals Thermal Stresses in the Wall Connections of Cast Grate Structures

2016 ◽  
Vol 16 (4) ◽  
pp. 11-16 ◽  
Author(s):  
A. Bajwoluk ◽  
P. Gutowski
Keyword(s):  
Heat Treatment ◽  
Cross Section ◽  
Hot Spots ◽  
Thermal Stresses ◽  
Cooling Process ◽  
Temperature Variations ◽  
Temperature Changes ◽  
Different Types ◽  
The Difference ◽  
The Impact

Abstract The purpose of this study was to establish a relationship between the type of wall connection used in the cast grates, which are part of the equipment operating in furnaces for heat treatment and thermal-chemical treatment, and stresses generated in these grates during the process of rapid cooling. The places where the grate walls are connected to each other are usually characterized by the thickness larger than the remaining parts of walls. Temperature variations in those places are responsible for the formation of hot spots, and in the hot spots temperature changes much more slowly. The type of wall connection shapes the temperature gradient in the joint cross-section, and hence also the value of thermal stresses generated during cooling. In this study, five different designs of the grates were compared; the difference in them was the type of the designed wall connection. The following design variants were adopted in the studies: X connections with and without holes, T connections with and without technological recesses, and R (ring) connection. Numerical analysis was performed to examine how the distribution of temperature changes in the initial phases of the cooling process. The obtained results served next as a tool in studies of the stress distribution in individual structures. The analysis were carried out by FEM in Midas NFX 2014 software. Based on the results obtained, the conclusions were drawn about the impact of different types of wall connections on the formation of thermal stresses in cast grates.

Northumberland Strait bridge: analysis techniques and results

1996 ◽  
Vol 23 (1) ◽  
pp. 86-97 ◽  
Author(s):  
Amin Ghali ◽  
Gamil Tadras ◽  
Paul H. Langohr
Keyword(s):  
Cross Section ◽  
Structural Design ◽  
Major Part ◽  
Thermal Stresses ◽  
Atlantic Coast ◽  
Variable Depth ◽  
Analysis Techniques ◽  
Ice Forces ◽  
Creep And Shrinkage

The Northumberland Strait at the Atlantic coast of Canada will be crossed by a 13 km bridge. The major part of the superstructure will consist of 44 spans, each of length 250 m and a box cross section of variable depth 4.5–14 m. The superstructure, divided into units of maximum length 192 m, will be produced in a yard by segmental casting and multistage prestressing. These units will be assembled at their final position on top of the piers. Each pier is composed of two pieces, also produced in the yard and connected on site by cast in situ concrete. This paper describes selected analysis problems and their solutions employed in the structural design. The analysis problems are concerned with (i) dynamic response to ice forces; (ii) movements of pier footings and stiffness of the subgrade; (iii) variation of stresses and deformations during construction and during the life of the structure, considering the effects of creep and shrinkage of concrete and relaxation of the prestressed steel; and (iv) thermal stresses. Key words: bridges, concrete, creep, prestress relaxation, segmental construction, shrinkage, strait crossing.

The Program Design of the Variable Cross-Section of Concrete Continuous Skew Beam Bridge

2008 ◽  
Vol 400-402 ◽  
pp. 633-638
Author(s):  
Min Chen ◽  
Zhong Chu Tian ◽  
Guo Liang Zeng
Keyword(s):  
Cross Section ◽  
Concrete Beams ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Girder Bridges ◽  
Practical Engineering ◽  
Uniform Cross Section ◽  
Girder Bridge ◽  
Beam Bridge ◽  
Compound Section

In practical engineering, we often encounter designs of variable cross-section or compound section skew girder bridge. While in many bibliographies, uniform cross-section of the concrete beams studying was carried out, but few of variable cross-section concrete beams were in-depth studied. Based on analyzing the mechanical behavior of variable cross-section beam skew girder bridge, the semi-analytic solution of variable cross-section beam skew girder bridges were provided in this paper. With this method developed a planar computation program to resolve the calculation problems of skew girder bridge, a more convenient way will be brought up for designers in calculation.

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