scholarly journals Effect of Initial On-Site Curing on 28-Day Cylinder Strength

2011 ◽  
Vol 108 (5) ◽  
Keyword(s):  
Cylinder Strength

Flexural design of precast, prestressed ultra-high-performance concrete members

PCI Journal ◽  
2020 ◽  
Vol 65 (6) ◽  
pp. 35-61
Author(s):  
Chungwook Sim ◽  
Maher Tadros ◽  
David Gee ◽  
Micheal Asaad
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Limit State ◽  
Design Guidelines ◽  
Design Tool ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Concrete Members ◽  
Cylinder Strength

Ultra-high-performance concrete (UHPC) is a special concrete mixture with outstanding mechanical and durability characteristics. It is a mixture of portland cement, supplementary cementitious materials, sand, and high-strength, high-aspect-ratio microfibers. In this paper, the authors propose flexural design guidelines for precast, prestressed concrete members made with concrete mixtures developed by precasters to meet minimum specific characteristics qualifying it to be called PCI-UHPC. Minimum specified cylinder strength is 10 ksi (69 MPa) at prestress release and 18 ksi (124 MPa) at the time the member is placed in service, typically 28 days. Minimum flexural cracking and tensile strengths of 1.5 and 2 ksi (10 and 14 MPa), respectively, according to ASTM C1609 testing specifications are required. In addition, strain-hardening and ductility requirements are specified. Tensile properties are shown to be more important for structural optimization than cylinder strength. Both building and bridge products are considered because the paper is focused on capacity rather than demand. Both service limit state and strength limit state are covered. When the contribution of fibers to capacity should be included and when they may be ignored is shown. It is further shown that the traditional equivalent rectangular stress block in compression can still be used to produce satisfactory results in prestressed concrete members. A spreadsheet workbook is offered online as a design tool. It is valid for multilayers of concrete of different strengths, rows of reinforcing bars of different grades, and prestressing strands. It produces moment-curvature diagrams and flexural capacity at ultimate strain. A fully worked-out example of a 250 ft (76.2 m) span decked I-beam of optimized shape is given.

scholarly journals Parametric study of the strength of reinforced concrete polygonal sections submitted to oblique composite flexion

2020 ◽  
Vol 13 (5) ◽  
Author(s):  
Lucas Peres de Souza ◽  
Marco André Argenta
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Bending Strength ◽  
Computational Algorithm ◽  
Bending Moment ◽  
Failure Surface ◽  
Surface Shape ◽  
Axial Loads ◽  
Interaction Diagram ◽  
Cylinder Strength

abstract: This work aims to verify the influence of characteristic compressive cylinder strength ( f c k), section geometry and eccentric axial load on the strength of square, cross, “T” and “L” reinforced concrete sections, under oblique composite flexion. A computational algorithm was created to calculate sections interaction diagram of bending strength, taking into account NBR 6118 idealized parabola-rectangle stress-strain relationships for 20 to 90 MPa f c k concretes. The results show that f c k influence is stronger for higher values of axial load and that the failure surface shape in interaction diagrams depends directly on the f c k and on the rebars distribution in the section. Furthermore, under lower compressive axial loads, higher oblique composite flexion strengths are reached when there is more reinforcement area in tension regions but, as the compression increases, the reinforcement presence and larger concrete areas in compression zones provide higher bending moment strengths.

scholarly journals Mechanical properties of lightweight concrete with sintered aggregate

2020 ◽  
Vol 323 ◽  
pp. 01005
Author(s):  
Anna M. Rogowska ◽  
Paweł M. Lewiński
Keyword(s):  
Tensile Strength ◽  
Power Plants ◽  
Lightweight Concrete ◽  
Building Structures ◽  
Engineering Structures ◽  
Concrete Shrinkage ◽  
Axial Tensile ◽  
Cylinder Strength ◽  
Complex Engineering

The objective of this paper is the determination of short-term properties of lightweight concrete with sintered aggregate. The aggregate material comes from the recycling of ashes from power plants, which yield granules after processing. The research was planned based on two concrete mixes. A series of tests was carried out in the ITB Laboratory of Building Structures, Geotechnics and Concrete. As a result of these tests, the following parameters were determined: secant modulus of elasticity and cylinder strength of concrete, cube strength of concrete, axial tensile strength, splitting tensile strength, flexural strength and concrete shrinkage. Knowledge of the tested parameters is necessary when designing prestressed structures, as well as accepting proven values for static calculations when designing complex engineering structures, including prestressed elements made of lightweight concrete.

scholarly journals BUCKLING OF SLENDER COMPOSITE CONCRETE‐FILLED STEEL COLUMNS

2010 ◽  
Vol 16 (2) ◽  
pp. 230-236 ◽  
Author(s):  
C. Douglas Goode ◽  
Artiomas Kuranovas ◽  
Audronis Kazimieras Kvedaras
Keyword(s):  
Bearing Capacity ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Hollow Section ◽  
Steel Columns ◽  
Tubular Columns ◽  
Cylinder Strength ◽  
Experimental Values ◽  
Concrete Filled Steel Tubes

The paper presents the analysis of the experimental data of 1817 on concrete‐filled steel tubes ‐ CFSTs. These results are compared with the predicted results of the load‐bearing capacity of calculations of slender elements according to the methods suggested by Eurocode 4. The following types of tested CFSTs were analysed: circular and rectangular hollow section stub and long columns fully filled with concrete, which were with or without applied moments at the ends of specimen. During the results obtained in the result of the tests on the load bearing capacity for circular concrete‐filled steel tubular columns correspond with the calculated values based on methods presented by Eurocode 4. The experimental values of load bearing capacity for members of concrete‐filled rectangular hollow sections agree very well with the theoretical values where the concrete cylinder strength is below 75 N/mm2. The analysis demonstrated that preloading of concrete‐filled hollow section members does not influence the load bearing capacity. This paper also presents the examination of stress state distribution for concrete‐filled hollow section members, influence of concrete preloading and of longitudinal stress strain curves. Santrauka Straipsnyje aptariami 1817 betonšerdžiu plieniniu vamzdiniu strypu eksperimentiniai duomenys. Šie duomenys lyginami su rezultatais, gautais remiantis Eurocode 4 pateiktais kompozitiniu elementu laikomosios galios nustatymo metodais. Analizuojami tokie betonšerdžiu plieniniu strypu bandiniu tipai: pilnavidures trumpos arba liaunos apskritojo ir stačiakampio skerspjūvio vamzdines betonšerdes plienines kolonos su ju galuose veikiančiu lenkiamuoju momentu arba be jo. Apskritojo skerspjūvio betonšerdžiu kolonu bandymu metu gautieji laikomosios galios rezultatai atitinka remiantis Eurocode 4 pateiktais metodais apskaičiuotasias ju reikšmes. Stačiakampio skerspjūvio betonšerdžiu elementu laikomosios galios bandymais rastosios reikšmes labai gerai atitinka teorines reikšmes, kai šerdies betono ritininis stipris nesiekia 75 N/mm2. Analizuojant nustatyta, kad išankstinis betonšerdžiu elementu apkrovimas neturi beveik jokio poveikio elementu laikomajai galiai. Šiame straipsnyje taip pat nagrinejamas betonšerdžiu elementu itempiu būviu pasiskirstymas, betono apspaudimo poveikis bei išilginiu deformaciju ir itempiu kreives.

Mechanical Properties of Concrete with Ground Waste Tire Rubber

1996 ◽  
Vol 1532 (1) ◽  
pp. 66-72 ◽  
Author(s):  
David Fedroff ◽  
Shuaib Ahmad ◽  
Banu Zeynep Savas
Keyword(s):  
Environmental Problem ◽  
The United States ◽  
Strain Response ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Cylinder Strength ◽  
Hardened Properties ◽  
Waste Tire Rubber ◽  
Stiffness Characteristics ◽  
Strength And Stiffness

Because used tires represent an increasingly serious environmental problem in the United States, this study was undertaken to examine the feasibility of using finely ground rubber in Portland-cement concrete. Various percentages of rubber, by weight of cement, were added to a control mix and the effects on the plastic and hardened properties of concrete were investigated. Workability of the mixes was affected, but it was controllable. For hardened concretes, the tests were conducted for compressive strength, split-cylinder strength, modulus of elasticity, and flexural strength. Stress-strain response was also investigated. The strength and stiffness characteristics were markedly reduced for rubcrete mixtures.

Influence of Delamination on Strength of Externally Pressurized Glass/Epoxy Cylinders

1999 ◽  
Author(s):  
Peter Davies ◽  
Leif A. Carlsson
Keyword(s):  
Impact Damage ◽  
Compressive Load ◽  
External Pressure ◽  
Cylinder Wall ◽  
Failure Pressure ◽  
Filament Wound ◽  
Local Reduction ◽  
Delamination Resistance ◽  
Cylinder Strength ◽  
Winding Angle

Abstract The delamination resistance of filament wound glass/epoxy cylinders has been characterized for a range of winding angles and fracture mode ratios using beam fracture specimens. The results reveal that the fracture resistance increases with increasing winding angle and mode II (shear) fraction (GII/G). It was also found that interlaced fiber bundles in the filament wound cylinder wall acted as effective crack arresters in mode I loading. To examine the sensitivity of delamination damage on the implosion behavior of cylinders, external pressure tests were performed on filament-wound glass/epoxy composite cylinders with artificial defects and impact damage. The results revealed that the cylinder strength was insensitive to the presence of single delaminations but impact damage caused reductions in failure pressure. The insensitivity of the failure pressure to a single delamination is attributed to the absence of buckling of the delaminated sublaminates before the cylinder wall collapsed. The impacted cylinders contained multiple delaminations, which caused local reduction in the compressive load capability and reduction in failure pressure.

Design Application of LQS20000 Column Strength Test Bench

2013 ◽  
Vol 744 ◽  
pp. 128-131
Author(s):  
Peng Fei Lui ◽  
Xiao Wei Shao ◽  
Xiang Hui Meng
Keyword(s):  
Test Bench ◽  
Strength Test ◽  
Loading Test ◽  
Hydraulic Support ◽  
Cylinder Strength ◽  
Stable Performance ◽  
Dual Extension ◽  
Working Resistance ◽  
Test Requirements ◽  
New Criterion

Analyzed the trend of the development of hydraulic powered support and column, this paper designs a column strength test bench with 20000KN working resistance which combined with the new release of GB25974.2-2010 for coal mine hydraulic support and jack technical conditions of Part 2 standard requirements. Through the practical application, it turned out that the test bench has reasonable structure, stable performance and it can meet all of the following Ф630 bore hydraulic support column factory test requirements. The trend of the mine-used hydraulic support column and the performed new criterion demands manufacturers to enhance the ability of test equipment. In this situation, the 20000KN column strength test bench our company designed and manufactured not only do the loading test, but also apply external load at columns by simulating the actual working conditions, which is essential to Inspection and testing of dual-extension hydraulic columns middle cylinder strength.

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