scholarly journals Consolidated effect of fiber-reinforcement and concrete strength class on mechanical performance, economy and footprint of concrete for pavement use

2021 ◽  
Author(s):  
Babar Ali ◽  
Erol Yilmaz ◽  
Muhammad Sohail Jameel ◽  
Waqas Haroon ◽  
Rayed Alyousef
Keyword(s):  
Strength Class ◽  
Mechanical Performance ◽  
Concrete Strength ◽  
Fiber Reinforcement

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 Axial Compressive Behaviour of Square Through-Beam Joints between CFST Columns and RC Beams with Multi-Layers of Steel Meshes

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2482
Author(s):  
Weining Duan ◽  
Jian Cai ◽  
Xu-Lin Tang ◽  
Qing-Jun Chen ◽  
Chun Yang ◽  
...  
Keyword(s):  
Axial Compression ◽  
Mechanical Performance ◽  
Concrete Strength ◽  
Volume Ratio ◽  
Design Criterion ◽  
Design Methods ◽  
Rc Beams ◽  
Compressive Behaviour ◽  
Joint Area ◽  
Cfst Columns

The axial compressive behaviour of an innovative type of square concrete filled steel tube (CFST) column to reinforced concrete (RC) beam joint was experimentally investigated in this paper. The innovative joint was designed such that (i) the steel tubes of the CFST columns were completely interrupted in the joint region, (ii) the longitudinal reinforcements from the RC beams could easily pass through the joint area and (iii) a reinforcement cage, including a series of reinforcement meshes and radial stirrups, was arranged in the joint area to strengthen the mechanical performance of the joint. A two-stage experimental study was conducted to investigate the behaviour of the innovative joint under axial compression loads, where the first stage of the tests included three full-scale innovative joint specimens subjected to axial compression to assess the feasibility of the joint detailing and propose measures to further improve its axial compressive behaviour, and the second stage of the tests involved 14 innovative joint specimens with the improved detailing to study the effect of the geometric size of the joint, concrete strength and volume ratio of the steel meshes on the bearing strengths of the joints. It was generally found from the experiments that (i) the innovative joint is capable of achieving the design criterion of the ‘strong joint-weak member’ with appropriate designs, and (ii) by decreasing the height factor and increasing the volume ratio of the steel meshes, the axial compressive strengths of the joints significantly increased, while the increase of the length factor is advantageous but limited to the resistances of the joint specimens. Because of the lack of existing design methods for the innovative joints, new design expressions were proposed to calculate the axial compression resistances of the innovative joints subjected to bearing loads, with the local compression effect, the confinement effect provided by the multi-layers of steel meshes and the height effect of concrete considered. It was found that the proposed design methods were capable of providing accurate and safe resistance predictions for the innovative joints.

scholarly journals Petrographic and Mechanical Characteristics of Concrete Produced by Different Type of Recycled Materials

Geosciences ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 264 ◽  
Author(s):  
Petros Petrounias ◽  
Panagiota P. Giannakopoulou ◽  
Aikaterini Rogkala ◽  
Paraskevi Lampropoulou ◽  
Basilios Tsikouras ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Mechanical Characteristics ◽  
Strength Class ◽  
Concrete Strength ◽  
Glass Waste ◽  
Recycled Materials ◽  
Curing Conditions ◽  
Different Types ◽  
Green Glass ◽  
Water Saturated

This paper examined three different types of recycled materials, such as beer green glass, waste tile, and asphalt, which will be used in different mixtures in order to prepare concrete specimens and, more specifically, their effect on concrete strength and how the petrographic characteristics of various recycled materials influenced the durability of C25/30 strength class concrete. Particular emphasis was placed on the effect of artificial microroughness of glassy and smooth surfaces of recycled materials on their final concrete strength. The concrete strength values do not show great variance, but their limited differences have been qualitatively interpreted by a new promising petrographic methodology, including the study of the surface texture of the used aggregate materials. Concretes are produced with constant volume proportions, workability, mixing, and curing conditions while using different sizes of each aggregate type. The aggregates were mixed both in dry and water saturated states in concretes. Concretes that are made by a mixture of beer green glass with quartz primer, as well as of tile with quartz primer, presented the optimum possible results of the compressive strength.

Effects of Water-Borne Polyurethane on Calcium Silicate Hydrate and Toughness of Properties of Cementitious Composites

2012 ◽  
Vol 619 ◽  
pp. 545-552
Author(s):  
Bei Ding ◽  
Xia Zhang ◽  
Dong Liang Zhou ◽  
Chan Wen Miao
Keyword(s):  
Mechanical Performance ◽  
Concrete Strength ◽  
Harmful Effect ◽  
Impact Resistance ◽  
29Si Nmr ◽  
Size Change ◽  
Block Polymer ◽  
Chain Conformations ◽  
The Impact ◽  
Water Borne

A novel kind of block polymer with characteristics of rod-like chain conformations-water-borne polyurethane (PUA) was synthesized by incorporate polyacrylate (PA) into the PU chain to prepare an aqueous polyurethane-polyacrylate (PUA) hybrid emulsion with core-shell structure. The interactions between Water-borne PUA and C-S-H nanostructure, which include intercalation and the polymerization degree of C-S-H silicate chains, were studied by small angle X-ray diffraction spectra and 29Si NMR spectra, respectly. The influences of water-borne PUA on mechanical performance of C-S-H were investigated experimentally. The small XRD results show that no evidence is observed for any fundamental size change in the C-S-H particles that have been formed in the presence of polymer. The NMR results indicate that there is a significant increase in the Q2/Q1 ratio ranging from 0.5 for pure C-S-H to 2.2 for PUA-C-S-H, respectively. The degree of silicate polymerization increases from 3.0 for pure C-S-H to 6.4 for PUA-C-S-H by calculation. PUA had minimal harmful effect on the compressive strength whereas the flexural strength was increased by 23.2% with dosage of 0.5% and 23.3% with dosage of 1.0%, respectively.The fracture energy ratios of concrete with a dosage of PUA less than 1% are greatly improved more than double with the decreasing of concrete strength less than 10%. The water-borne PUA also enhances the impact resistance of concrete. The impact energy consumption of samples with PUA increase nearly three times more than reference samples, also better than samples with PP fiber.

How does concrete strength affect the fire resistance?

2020 ◽  
Vol 11 (3) ◽  
pp. 311-324
Author(s):  
Eva Lubloy
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Fire Safety ◽  
Strength Class ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Building Structures ◽  
Content Type ◽  
Upper Limit

Purpose The aim of the research was to investigate the effect of concrete strength on the fire resistance of structures. At first, it may seem contradictory that higher concrete strengths can decrease the fire resistance of building structures. However, if the strength of the concrete exceeds a maximum value, the risk of spalling (the detachment of the concrete surface) significantly. Design/methodology/approach Prefabricated structural elements are often produced with higher strength. The higher concrete strengths generally do not cause a reduction in the load bearing capacity, but it can have serious consequences in case of structural fire design. Results of two prefabricated elements, namely, one slab (TT shaped panel) and one single layer wall panel, were examined. Results of the specimen with the originally designed composition and a specimen with modified concrete composition were examined, were polymer fibres were added to prevent spalling. Findings As a result of the experiments, more strict regulations in the standards the author is suggested including more strict regulations in the standards. It has been proved that to ensure the fire safety of the reinforced concrete structures, it is required after polymer fibres even in lower concrete strength class than prescribed by the standard. In addition, during the classification and evaluation of structures, it is advisable to introduce an upper limit of allowed concrete strength for fire safety reasons. Originality/value As a result of the experiments, the author suggests including more strict regulations in the standards. It has been proved that to ensure the fire safety of the reinforced concrete structures, it is necessary to require the addition of polymer fibres even in lower concrete strength class than prescribed by the standard. In addition, during the classification and evaluation of structures, it is advisable to introduce an upper limit of allowed concrete strength for fire safety reasons.

scholarly journals Comparison between resistant load contours generated considering the parabolic-rectangular (DPR) and the rectangular (DR) stress-strain diagrams for rectangular sections under combined axial compression and biaxial bending

2018 ◽  
Vol 11 (3) ◽  
pp. 455-473
Author(s):  
Y. F. FONSECA ◽  
A. S. C. SILVA
Keyword(s):  
Axial Compression ◽  
Cross Section ◽  
Cross Sections ◽  
Strength Class ◽  
Concrete Strength ◽  
Strain Diagram ◽  
Biaxial Bending ◽  
Stress Strain ◽  
Oblique Loading ◽  
Stress Diagram

Abstract The aim of this study is to compare the load contour diagrams generated for rectangular RC cross-sections under combined axial compression and biaxial bending obtained by the two forms of analysis allowed by NBR 6118:2014 [1]: the first using the parabolic-rectangular stress-strain diagram (DPR) and the second using the rectangular (constant stress) diagram (DR). In order to compare the load contours generated, a reference cross-section was adopted for which the concrete strength class (from C20 to C90) and the deformation domains (4, 4a and 5) were varied for the study. It was studied whether the use of the different diagrams (DPR or DR) would provide greater (or smaller) resistant efforts for the same section. The results show that the use of the DR is only acceptable when the section is working up to the 4th domain. Above this domain, it was observed that the use of this diagram shows resistant efforts inferior to those calculated by the DPR. In addition, it was found that, for concretes with resistance class above C50, in oblique loading directions, the use of the DR presents higher resistant efforts than those calculated using the DPR.

Microstructural Features of Recycled Aggregate Concrete: From Non-Structural to High-Performance Concrete

2019 ◽  
Vol 25 (3) ◽  
pp. 601-616 ◽  
Author(s):  
Diogo Pedro ◽  
Mafalda Guedes ◽  
Jorge de Brito ◽  
Luís Evangelista
Keyword(s):  
High Performance ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Sequential Approach

AbstractThe use of concrete-recycled aggregates to produce high-performance concrete is limited by insufficient correlation between resulting microstructure and its influence on mechanical performance reproducibility. This work addresses this issue in a sequential approach: concrete microstructure was systematically analyzed and characterized by scanning electron microscopy and results were correlated with concrete compressive strength and water absorption ability. The influence of replacing natural aggregates (NA) with recycled concrete aggregates (RCA), with different source concrete strength levels, of silica fume (SF) addition and of mixing procedure was tested. The results show that the developed microstructure depends on the concrete composition and is conditioned by the distinct nature of NA, recycled aggregates from high-strength source concrete, and recycled aggregates from low-strength source concrete. SF was only effective at concrete densification when a two-stage mixing approach was used. The highest achieved strength in concrete with 100% incorporation of RCA was 97.3 MPa, comparable to that of conventional high-strength concrete with NA. This shows that incorporation of significant amounts of RCA replacing NA in concrete is not only a realistic approach to current environmental goals, but also a viable route for the production of high-performance concrete.

Effect of High Proportion of Blended Cement in Concrete

2014 ◽  
Vol 897 ◽  
pp. 230-233 ◽  
Author(s):  
Klára Křížová ◽  
Rudolf Hela
Keyword(s):  
Modulus Of Elasticity ◽  
Strength Class ◽  
Concrete Strength ◽  
Blended Cement ◽  
Mix Design ◽  
Concrete Compressive Strength ◽  
Static Modulus ◽  
Static Modulus Of Elasticity ◽  
The Given

The paper is concerned with assessment of blended cement high proportion in mix design of concrete. A long term development of concrete compressive strength and static modulus of elasticity were monitored. The cement proportion reached even 450 kg per m3 of concrete. The high proportion of blended cement was used with aim to obtain declared modulus of elasticity values for the given concrete strength class according to EN 1992-1-1. And just the blended cement influence was positively verified in the long-term development of both monitored parameters.

scholarly journals RESEARCH ON LOAD CAPACITY OF CONCRETE FILLED COLUMNS WITH BATTENED STEEL SECTIONS

2010 ◽  
Vol 16 (3) ◽  
pp. 313-319 ◽  
Author(s):  
Elzbieta Szmigiera ◽  
Wojciech Zoltowski ◽  
Miroslaw Siennicki
Keyword(s):  
Numerical Analysis ◽  
Strength Class ◽  
Load Capacity ◽  
Concrete Strength ◽  
General Purpose ◽  
Additional Increase ◽  
Finite Element Program ◽  
Steel Columns ◽  
Element Program ◽  
Steel Sections

The paper presents experimental and numerical results for selected built‐up steel columns filled with concrete. The laboratory tests were accompanied by numerical analysis carried out using general purpose, finite element program ABAQUS. Based on heretofore research presented in this paper, one may assumes that the application of concrete filled columns with battened steel sections is economically very profitable. For columns filled with concrete strength class C20/25 the increase of load bearing capacity was 42% and for elements filled with concrete strength class C50/60 ‐ above 100%. The application of the shorter distance between battens allowed to obtain additional increase of ultimate load (for concrete C20/25 ‐ about 8%). The numerical analysis also confirmed the increase of the load capacity for the columns. The best correlation between numerical and experimental results was obtained for the assumed eccentricity of 1 mm. Moreover the higher rigidity of those members in relation to steel columns is not connected with significant increase of the cost. The study was conducted as a part of the research project nr 4TO7E01528, founded by the Polish Ministry of Science and Higher Education. Santrauka Straipsnyje pristatomi plieniniu kolonu, užpildytu dvieju tipu betonu, eksperimentiniai ir skaitiniai tyrimu rezultatai. La‐boratoriniai bandymai ir skaitine analize buvo atliekami naudojant bendrosios paskirties baigtiniu elementu programa ABAQUS. Remiantis šiame straipsnyje pateiktais tyrimo rezultatais, galima daryti prielaida, kad kolonos iš standžiu plieniniu skerspjūviu, užpildytu betonu, yra labai ekonomiškos. Kolonos, užpildytos C20/25 betonu, laikomoji galia padidejo 42 %, o elemento, užpildyto C50/60, ‐ daugiau negu 100 %. Kai atstumas tarp sutvirtintu vietu trumpesnis, galima padidinti didžiausiaja apkrova (naudojant betono klase C20/25 ‐ apie 8 %). Skaitine analize patvirtino padidejusia kolonu laikomaja galia. Geriausia koreliacija tarp eksperimentiniu ir skaitiniu rezultatu buvo gauta esant tariamam 1 mm ekscentricitetui. Be to, didesnis šiu elementu standumas, palyginti su plieninemis kolonomis, nera susijes su išlaidu padidejimu. Šis mokslinis tyrimas buvo mokslinio projekto Nr. 4TO7E01528, kuri inicijavo Lenkijos studiju ir aukštojo mokslo ministerija, dalis.

scholarly journals Finite element analysis of bolt shear connection of steel-concrete composite structure

2020 ◽  
Vol 198 ◽  
pp. 01027
Author(s):  
Zhishun Pan
Keyword(s):  
Finite Element ◽  
Composite Structure ◽  
Composite Structures ◽  
Mechanical Performance ◽  
Concrete Strength ◽  
High Strength ◽  
Shear Capacity ◽  
Simulation Software ◽  
Element Analysis ◽  
Shear Connectors

Bolted shear connectors are an important component to ensure that steel-concrete composite structures can work together. High-strength bolt shear connectors can replace traditional stud connectors because of their disassembly, good mechanical performance and fatigue resistance. It applied to steel-concrete composite structure. In order to study the influencing factors of the bearing capacity of high-strength bolted shear connectors, this paper uses ABAQUS finite element simulation software as a research tool to establish a reasonable finite element model to study the influence of bolt strength, bolt diameter and concrete strength on bolted shear connectors. Studies have shown that increasing the diameter, strength, and concrete strength of bolted connections can effectively increase the bolt’s shear capacity.

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