scholarly journals Refined strength prediction of concrete 2D bottle-shaped struts

2021 ◽  
Vol 4 (2) ◽  
pp. 111-125
Author(s):  
Abdelrazek E. Ebrahim ◽  
Omar M. Elmeligy ◽  
Salah E. El-Metwally ◽  
Mashhour A. Ghoneim ◽  
Hamed S. Askar
Keyword(s):  
Concrete Strength ◽  
High Strength ◽  
Experimental Tests ◽  
Strength Prediction ◽  
Width Ratio ◽  
Element Analysis ◽  
Minimum Reinforcement ◽  
Strength Concrete ◽  
Bearing Plate ◽  
Effectiveness Factors

For better strength prediction using strut-and-tie models (STM), it is essential to use reliable strength parameters of the model components; e.g., struts, ties, and nodes. Among all the elements of the STM, the strength of the bottle-shaped struts is not well quantified. The purpose of this study is to develop more accurate formulas for the calculation of the effectiveness factors for 2D bottle-shaped struts, that are unreinforced, reinforced with minimum reinforcement, and reinforced with sufficient transverse reinforcement. The nonlinear finite element analysis, with the aid of the software ABAQUS, has been utilized in this study, which has been verified against experimental tests. The study has been carried out for grades of concrete varying from 20 to 100MPa, and for bearing plate to width ratio varying from 0.1 to 0.9. The obtained formulas for the effectiveness factors of bottle-shaped struts are functions of the concrete strength, which is not the case with the ACI 318-19 provisions. These formulas have been verified against experimental tests and have been compared with the ACI 318-19 provisions. The predictions based on these formulas are more accurate than those based on the ACI 318-19 provisions. Also, the results from these formulas are always on the safe side. On the other hand, the ACI 318-19 provisions lead to unsafe results in the case of high-strength concrete and very conservative results for the case of unreinforced struts from normal-strength concrete.

Minimum flexural reinforcement for T-beams made of higher strength concrete

1999 ◽  
Vol 26 (5) ◽  
pp. 525-534 ◽  
Author(s):  
Guney Ozcebe ◽  
Ugur Ersoy ◽  
Tugrul Tankut
Keyword(s):  
Reinforced Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Crack Control ◽  
Minimum Reinforcement ◽  
Strength Concrete ◽  
The Past ◽  
Flexural Reinforcement ◽  
Reserve Strength

Design codes specify minimum flexural reinforcement for reinforced concrete beams. With the extensive use of higher strength concrete, the empirical expressions of the past for minimum flexural reinforcement, in which the concrete strength is not considered, had to be revised. Six reinforced concrete T-beams, having small ratios of flexural reinforcement, were tested to study the behaviour at the positive moment region and to evaluate the code requirements on minimum flexural reinforcement. A criterion was set and evaluations of different minimum reinforcement requirements were made using this criterion and the test data.Key words: beams, crack control, ductility, flexural strength, high strength concrete, minimum flexural reinforcement, reserve strength.

scholarly journals Elasto-plastic analysis of high-strength concrete shear wall with boundary columns using fiber model

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Xiaolong Tong ◽  
Fumin Chen ◽  
Yangjing Ou ◽  
Sixi Xiao ◽  
Jianliang Wu
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
High Strength ◽  
Shear Wall ◽  
Width Ratio ◽  
Longitudinal Reinforcement ◽  
Element Analysis ◽  
Strength Concrete ◽  
Vertical Reinforcement ◽  
Plastic Analysis

In this study, an experimental study and numerical calculations using fiber model were conducted for four high-strength concrete shear walls with boundary columns under low cyclic load. The boundary column and shear wall were divided into fiber elements, and PERFORM-3D finite element analysis software was used to carry out push-over analysis on the test specimens. The results show that the finite element analysis results were in good agreement with the experimental results. The proposed analysis method could perform elasto-plastic analysis on the high-strength concrete shear wall with boundary columns without distinguishing the categories of frame column and shear wall. The seismic performance of high-strength concrete shear wall with boundary columns was analyzed using the following parameters: axis compression ratio, height to width ratio, ratio of vertical reinforcement, and ratio of longitudinal reinforcement in the boundary column. The results show that the increase in the axial compression ratio causes the bearing capacity of the shear wall to increase at first and then to decrease and causes the ductility to decrease. The increase in the height to width ratio causes the bearing capacity of the shear wall to decrease and its ductility to increase. The ratio of vertical reinforcement was found to have little effect on the bearing capacity and ductility. The increase in the ratio of longitudinal reinforcement in boundary column resulted in a significant increase in the bearing capacity and caused the ductility to decrease at first and then to slowly increase.

scholarly journals Experimental Study on the Torsional Behaviour of Prestressed HSC Hollow Beams

2020 ◽  
Vol 10 (2) ◽  
pp. 642 ◽  
Author(s):  
Luís Bernardo ◽  
Sérgio Lopes ◽  
Mafalda Teixeira
Keyword(s):  
Experimental Study ◽  
High Strength Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Experimental Program ◽  
Pure Torsion ◽  
Strength Concrete ◽  
Hollow Beams

This article describes an experimental program developed to study the influence of longitudinal prestress on the behaviour of high-strength concrete hollow beams under pure torsion. The pre-cracking, the post-cracking and the ultimate behaviour are analysed. Three tests were carried out on large hollow high-strength concrete beams with similar concrete strength. The variable studied was the level of longitudinal uniform prestress. Some important conclusions on different aspects of the beams’ behaviour are presented. These conclusions, considered important for the design of box bridges, include the influence of the level of prestress in the cracking and ultimate behaviour.

Bond behavior of high strength concrete under reversed pull-out cyclic loading

2002 ◽  
Vol 29 (2) ◽  
pp. 191-200 ◽  
Author(s):  
M Alavi-Fard ◽  
H Marzouk
Keyword(s):  
Cyclic Loading ◽  
Bond Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Displacement Curve ◽  
Bond Slip ◽  
Strength Concrete ◽  
Pull Out ◽  
Normal Strength

Structures located in seismic zones require significant ductility. It is necessary to examine the bond slip characteristics of high strength concrete under cyclic loading. The cyclic bond of high strength concrete is investigated under different parameters, including load history, confining reinforcement, bar diameter, concrete strength, and the rate of pull out. The bond strength, cracking, and deformation are highly dependent on the bond slip behavior between the rebar and the concrete under cyclic loading. The results of cyclic testing indicate that an increase in cyclic displacement will lead to more severe bond damage. The slope of the bond stress – displacement curve can describe the influence of the rate of loading on the bond strength in a cyclic test. Specimens with steel confinement sustained a greater number of cycles than the specimens without steel confinement. It has been found that the maximum bond strength increases with an increase in concrete strength. Cyclic loading does not affect the bond strength of high strength concrete as long as the cyclic slip is less than the maximum slip for monotonic loading. The behavior of high strength concrete under a cyclic load is slightly different from that of normal strength concrete.Key words: bond, high strength, cyclic loading, bar spacing, loading rate, failure mechanism.

scholarly journals Finite Element Analysis on Behavior of Reinforced Hollow High Strength Concrete Filled Square Steel Tube Short Columns under Axial Compression

2021 ◽  
Vol 2101 (1) ◽  
pp. 012059
Author(s):  
Z J Yang ◽  
X Li ◽  
G C Li ◽  
S C Peng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Strength Concrete ◽  
Mechanical Performance ◽  
Concrete Strength ◽  
High Strength ◽  
Steel Tube ◽  
Element Analysis ◽  
Steel Strength ◽  
Square Steel Tube

Abstract Hollow concrete-filled steel tubular (CFST) member is mainly adopted in power transmission and transformation structures, but when it is used in the superstructure with complex stress, the hollow CFST member has a low bearing capacity and is prone to brittle failure. To improve the mechanical performance of hollow CFST members, a new type of reinforced hollow high strength concrete-filled square steel tube (RHCFSST) was proposed, and its axial compression performance was researched. 18 finite element analysis (FEA) models of axially loaded RHCFSST stub columns were established through FEA software ABAQUS. The whole stress process of composite columns was studied, and parametric studies were carried out to analyze the mechanical performance of the member. Parameters of the steel strength, steel ratio, deformed bar and sandwich concrete strength were varied. Based on the simulation results, the stress process of members can be divided into four stages: elastic stage, elastoplastic stage, descending stage and gentle stage. With the increase of steel strength, steel ratio, the strength of sandwich concrete and the addition of deformed bars, the ultimate bearing capacity of members also increases. Additionally, the increment of those parameters will improve the ductility of the member, except for the sandwich concrete strength.

scholarly journals Efficacy of Natural Zeolite and Metakaolin as Partial Alternatives to Cement in Fresh and Hardened High Strength Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Iswarya Gowram ◽  
Beulah M ◽  
MR Sudhir ◽  
Mothi Krishna Mohan ◽  
Deekshith Jain
Keyword(s):  
High Strength Concrete ◽  
Natural Zeolite ◽  
Environmental Concern ◽  
Concrete Strength ◽  
High Strength ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Split Tensile Strength ◽  
Carbon Footprints ◽  
Strength Concrete

Urbanization and industrialization have dramatically increased the manufacture of cement causing substantial pollution of the environment. The primary global concern related to cement manufacture has been the management of the large carbon footprints. The usages of environmentally friendly cementitious materials in the construction of structures have proved to be a viable option to deal with this environmental concern. Therefore, it is necessary to further explore the usage of cementitious materials which can replace cement albeit partially. In this direction of research, two such cementitious materials, namely, natural zeolite and metakaolin have been investigated in this study. High-strength concrete M60 with natural zeolite and metakaolin as the partial replacements for the cement has been prepared in this work. Polycarboxylic ether-based superplasticizer solution has been used to enhance workability. The test specimen cast and cured for 3, 7, 28, 60, and 90 days at ambient room temperature has been tested for compressive strength, split tensile strength, and flexural strength as per the Indian standards. The optimum mix of high-strength concrete thus manufactured has met the Indian standards, and the combination of cement +5% natural zeolite +10% metakaolin has exhibited the highest compressive, split tensile, and flexural strengths at 90 days of curing. Natural zeolite and metakaolin when used in smaller proportions have increased the concrete strength, and these materials are recommended for partial replacement of cement.

scholarly journals Cyclical Behavior of Concrete-Encased Composite Frame Joints with High Strength Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Lei Zeng ◽  
Zhenkun Cui ◽  
Yunfeng Xiao ◽  
Siqian Jin ◽  
Yuanyuan Wu
Keyword(s):  
Cyclic Loading ◽  
High Strength Concrete ◽  
Joint Strength ◽  
Concrete Strength ◽  
Outer Part ◽  
High Strength ◽  
Crack Pattern ◽  
Experimental Program ◽  
Strength Concrete ◽  
Composite Frame

This paper presents an application of high strength concrete to concrete-encased composite frame building based on an experimental program. The work emphasized joints behavior under reverse cyclic loading caused by earthquakes to provide information for seismic design. To investigate the internal mechanisms and seismic performance, cyclic loading tests were carried out on five half-scale interior joints. Two design variables were addressed in the research: concrete strength and axial column load. Frame joints performance including crack pattern, failure mode, deformation, ductility, strain distribution, and energy dissipation capacity was investigated. It was found that all joint specimens behaved in a manner with joint panel shear failure. Using high strength concrete increased the joint strength and had relatively little effect on the stiffness and ductility. The axial column load helped the joint strength by better mobilizing the outer part of the joint, but it had an obvious influence on the ductility and energy-dissipating capacity, which can be improved by providing enough transverse reinforcement. A typical crack pattern was also provided which can well reflect mechanical character and damage process. This research should contribute to the future engineering applications of high strength concrete to concrete-encased composite structure.

scholarly journals High-strength concrete eccentrically compressed elements

2019 ◽  
Vol 140 ◽  
pp. 02017
Author(s):  
Anastasia Vasilenko ◽  
Dmitry Chernogorsky ◽  
Dmitry Strakhov ◽  
Leonid Sinyakov
Keyword(s):  
Economic Efficiency ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Application Domain ◽  
Strength Concrete ◽  
Steel Ratio ◽  
Material Cost ◽  
Relative Eccentricity ◽  
Load Characteristics

The article is devoted to the analysis of technical and economic efficiency of application of high-strength concrete (HSC) in the eccentrically compressed columns. In the first part of the paper, the effect of concrete grade on in-creasing the column stiffness depending on steel ratio at different values of the relative eccentricity is considered. According to the results of the calculation, application of HSC is most effective at low values of the relative ec-centricity because increasing the concrete strength leads to more intensive increasing of column stiffness than increasing of steel ratio. In the second part of the paper, the material cost of the 1 linear meter of the column is calculated at the fixed value of column stiffness and application domain of HSC is defined in the case under consideration. In addition, load characteristics providing the efficiency of HSC application in the eccentrically compressed columns are determined.

scholarly journals Experimental Study of Composite Hollow RC Column under Uniaxial Compressive Load

2019 ◽  
Vol 9 (3) ◽  
pp. 373
Author(s):  
Deokhee Won ◽  
Seungjun Kim ◽  
Jihye Seo ◽  
and Young-Jong Kang
Keyword(s):  
Experimental Study ◽  
Concrete Strength ◽  
Compressive Load ◽  
High Strength ◽  
Transverse Reinforcement ◽  
Strength Concrete ◽  
Rc Column ◽  
Steel Composite ◽  
Normal Strength ◽  
Concentric Loading

This paper presents an experimental study of the behavior of a steel-composite hollow reinforced concrete (RC) column under concentric loading. The effects of important variables, such as concrete strength, inner tube thickness, hollow ratio, column diameter, and transverse reinforcement space, are presented in this study. The failure of composite hollow RC columns is characterized by the formation of an inclined shear sliding plane. When the column had a highly confined effect, the inclination of the shear sliding plane was 45°. This study shows that the required performance is achieved when the splice providing transverse reinforcement is fully bonded. Furthermore, the inner tube experiences buckling failure after reaching its maximum strength. The steel-composite hollow RC column with high-strength concrete (HSC) has lower ductility and toughness compared to a column with normal-strength concrete (NSC).

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