Fatigue Mechanism Revealed through Multistage Strength Degradation of Notched Concrete Beams under Sequential Loading

2012 ◽  
Vol 197 ◽  
pp. 36-40
Author(s):  
Zi Hai Shi ◽  
Yukari Nakamura ◽  
Masaaki Nakano
Keyword(s):  
Concrete Beam ◽  
Degradation Mechanism ◽  
Strength Degradation ◽  
Multiple Cracks ◽  
Fe Model ◽  
Structural Members ◽  
Cracking Behavior ◽  
Load Carrying ◽  
Spatially Distributed ◽  
Experimental Findings

Under cyclic loading, the material weakening processes in structural members inevitably involve multiple cracking originating from some of the spatially-distributed initial flaws and imperfections, and hence diverse cracking behaviors can be expected. It is known from previous studies on multiple cracks that, the cracking behavior in a structural member can abruptly change as a crack or a number of cracks reach a critical value of crack propagation, causing sudden strength degradation. In this study, by applying sequential loads at different locations of the same FE model of a notched beam, it is shown that this unique strength degradation mechanism can repeatedly occur as cracks propagate under sequential loads, leading to multistage strength degradation of the member. This result is in line with early experimental findings that the load-carrying capacity of a notched concrete beam under bending decreases in a similar fashion as the sizes of multiple initial notches are arbitrarily increased. This study has important implications for understanding the fundamental fatigue mechanisms of various engineering materials.

Improving the Performance of Structural Members by Incorporating Incinerated Bio-Medical Waste Ash in Reinforced Geopolymer Concrete

2022 ◽  
Vol 1048 ◽  
pp. 321-332
Author(s):  
A. Kumar Suresh ◽  
M. Muthukannan ◽  
R. Kanniga Devi ◽  
K. Kumar Arun ◽  
Ganesh A. Chithambar
Keyword(s):  
Medical Waste ◽  
Geopolymer Concrete ◽  
Structural Members ◽  
Cement Concrete ◽  
Toughness Index ◽  
Granulated Blast Furnace Slag ◽  
Strain Behaviour ◽  
Load Carrying ◽  
Reinforced Cement ◽  
Experimental Findings

This study aims to analyze the use of Incinerated Bio-Medical Waste Ash (IBWA) in reinforced concrete structural member with ground granulated blast furnace slag (GGBS) as an alternate building ingredient instead of cement. Biomedical waste was produced from various medical resources such as hospitals, medical institutes and research centres. GGBS is the waste generated from the steel plant. The climate is now being affected by the release of CO2 (global warming) from the Portland cement industries. Therefore, greater attention must be paid to study efforts to use geopolymer concrete. Geopolymer is a novel inorganic eco-friendly binding agent derived from an alkaline solution that stimulates aluminosilicate source material (GGBS, Rice Husk Ash, Quartz Powder, metakaolin, fly ash and Silica Fume). In this research, laboratory tests for Reinforced Geopolymer Concrete (RGPC) beams (deflection, ductility factor, flexural strength and toughness index) and columns (load-carrying ability, stress-strain behaviour and load-deflection behaviour) were conducted for three types of proportions using [30% IBWA – 70% GGBS Geopolymer concrete, GGBS Geopolymer concrete and Reinforced Cement Concrete. The experimental findings revealed that the performance of reinforced 30% IBWA – 70% GGBS geo-polymer beams and columns worked more effectively than reinforced cement concrete beams and columns.

MODELING OF STEEL FIBRES AS FLEXURAL CRACKS INHIBITOR IN REINFORCED CONCRETE BEAM

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
Mohd Yuasrizam Musa ◽  
Siti Hawa Hamzah ◽  
Norliyati Mohd Amin
Keyword(s):  
Concrete Beam ◽  
Steel Fibre ◽  
Reinforced Concrete Beam ◽  
Structural Members ◽  
Ansys Software ◽  
Steel Fibres ◽  
Flexural Failure ◽  
Experimental Findings ◽  
Stress Patterns ◽  
Magnitude Difference

Flexural cracks are most common problem on structural members which are subjected to bending moments. The introduction of steel fibres in concrete beam has been proposed as flexural cracks inhibitor. This research was conducted focusing on simply supported beam to determine the crack propagations in flexure by varying the 25 kg/m3 steel fibre content placement in the beam. The results showed stress patterns from ANSYS software are similar to the experimental findings with minimal magnitude difference of about 11 %. It is concluded that the steel fibre inhibits flexural cracks and delayed the flexural failure in beams as depicted in the experimental results from 11 beams. 

scholarly journals Vision-Based Structural FE Model Updating Using Genetic Algorithm

2021 ◽  
Vol 11 (4) ◽  
pp. 1622
Author(s):  
Gun Park ◽  
Ki-Nam Hong ◽  
Hyungchul Yoon
Keyword(s):  
Genetic Algorithm ◽  
Model Updating ◽  
Structural Parameters ◽  
Fe Model ◽  
Structural Members ◽  
Stiffness Reduction ◽  
Before And After ◽  
Scale Test ◽  
Fe Model Updating ◽  
Story Building

Structural members can be damaged from earthquakes or deterioration. The finite element (FE) model of a structure should be updated to reflect the damage conditions. If the stiffness reduction is ignored, the analysis results will be unreliable. Conventional FE model updating techniques measure the structure response with accelerometers to update the FE model. However, accelerometers can measure the response only where the sensor is installed. This paper introduces a new computer-vision based method for structural FE model updating using genetic algorithm. The system measures the displacement of the structure using seven different object tracking algorithms, and optimizes the structural parameters using genetic algorithm. To validate the performance, a lab-scale test with a three-story building was conducted. The displacement of each story of the building was measured before and after reducing the stiffness of one column. Genetic algorithm automatically optimized the non-damaged state of the FE model to the damaged state. The proposed method successfully updated the FE model to the damaged state. The proposed method is expected to reduce the time and cost of FE model updating.

Full scale test of a PC bridge to calibrate assessment methods

2021 ◽  
Author(s):  
Niklas Bagge ◽  
Jonny Nilimaa ◽  
Silvia Sarmiento ◽  
Arto Puurula ◽  
Jaime Gonzalez-Libreros ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Structural Response ◽  
Sensitivity Study ◽  
Assessment Method ◽  
Full Scale ◽  
Concrete Bridges ◽  
Fractional Factorial ◽  
Fe Model ◽  
Load Carrying ◽  
Existing Bridges

<p>In this paper, experiences on the development of an assessment method for existing bridges are presented. The method is calibrated using the results of full-scale testing to failure of a prestressed bridge in Sweden. To evaluate the key parameters for the structural response, measured by deflections, strains in tendons and stirrups and crack openings, a sensitivity study based on the concept of fractional factorial design is incorporated to the assessment. Results showed that the most significant parameters are related to the tensile properties of the concrete (tensile strength and fracture energy) and the boundary conditions. A finite element (FE) model in which the results of the sensitivity analysis were applied, was able to predict accurately the load-carrying capacity of the bridge and its failure mode. Two additional existing prestressed concrete bridges, that will be used to improve further the method, are also described, and discussed.</p>

Analytical study on repair method for steel I-girder bridges with corrosion damage considering its structural system behavior

2021 ◽  
Author(s):  
Ryoga Oura ◽  
Takashi Yamaguchi ◽  
Kentaro Arimura
Keyword(s):  
Carrying Capacity ◽  
Corrosion Damage ◽  
Load Carrying Capacity ◽  
Structural Members ◽  
Structural System ◽  
System Behavior ◽  
Girder Bridges ◽  
Load Carrying ◽  
Girder Bridge ◽  
The Individual

<p>Bridges are composed by many structural members which interact with each other to resist against various load combinations. Considering damage repair of one of its structural members, the relationship between the recovery of the individual load-carrying capacity due to the repair of a single member and the improvement of the load-carrying capacity of the structural system is not clear. In the present study, a full-scale FE analysis has been conducted for a steel I-girder bridge system with corrosion damages which have been repaired. The analysis considered, the structural system behavior, varying the repaired areas and the type of patch members. From the analytical results, it was found that, compared to the method in which the damaged portion is completely repaired, the amount of repair can be reduced by taking into account the structural system behavior and partially repair both the damaged and the adjacent intact girders.</p>

NUMERICAL SIMULATION AND TESTING OF A COMPOSITE-STIFFENED STRUCTURE UNDER COMBINED BUCKLING LOADS

2010 ◽  
Vol 10 (04) ◽  
pp. 871-884 ◽  
Author(s):  
E. KARACHALIOS ◽  
C. VRETTOS ◽  
Z. MARIOLI-RIGA ◽  
C. BISAGNI ◽  
P. CORDISCO ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fe Model ◽  
Release Rates ◽  
Actual Structure ◽  
Physical Test ◽  
Buckling Behavior ◽  
Energy Release Rates ◽  
Experimental Findings ◽  
Teflon Film ◽  
Level Of Agreement

Prediction of the buckling behavior of structures is of great interest in the aerospace industry, and extensive research is taking place worldwide in that area. The current work concerns numerical simulation of the collapse test of a closed stiffened composite box subjected to compression followed by torsion. Numerical simulation is performed and the results are correlated with experimental findings. The objective is to validate the numerical model and detect any deficiencies of the modeling procedure. For this purpose, a series of quantities numerically predicted are directly compared with experimental ones: strains, displacements, deformation plots and load–displacement curves. The physical test article also contains artificial stringer–skin debondings realized via Teflon film inserts. The energy release rates are calculated at the debonding front using the virtual crack closure technique. The FE model is slightly stiffer than the actual structure but the numerical results are at a reasonable level of agreement with the experimental data.

Strength degradation mechanism of iron coke prepared by mixed coal and Fe2O3

2020 ◽  
Vol 150 ◽  
pp. 104897 ◽  
Author(s):  
Chen Yin ◽  
Shuxing Qiu ◽  
Shengfu Zhang ◽  
Farooq Sher ◽  
Hua Zhang ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Strength Degradation

APPLICATION OF UNCERTAINTY ANALYSIS TO STABILITY PROBLEMS OF STEEL-CONCRETE STRUCTURAL MEMBERS

2009 ◽  
Vol 1 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Libor Puklický ◽  
Zdeněk Kala
Keyword(s):  
Epistemic Uncertainty ◽  
Limit State ◽  
Ultimate Limit State ◽  
Load Carrying Capacity ◽  
Structural Members ◽  
Load Carrying ◽  
Steel Sections ◽  
Limit Stress ◽  
Ultimate Limit

The paper deals with the fuzzy analysis of the ultimate limit state of a steel strut with an encased web in compression. The first part of the paper lists presumptions required for the determination of the theoretical load carrying capacity for the column. Stresses in the concrete and steel sections are determined according to the principles of elasticity. The ultimate limit state is given as the limit stress attained in the most stressed section of either the steel or concrete section. A general extended principle, which takes into account the epistemic uncertainty of input parameters, was utilized for the conducted analysis.

Sign in / Sign up

Export Citation Format

Share Document