scholarly journals Evaluación de concreto elaborado con agregados de canteras de río y de cerro de los Andes del norte de Perú

2021 ◽  
Vol 4 (2) ◽  
pp. 4-13
Author(s):  
Lorena Uriarte Herrera ◽  
◽  
Edwar Cieza Sánchez
Keyword(s):  
American Concrete Institute

El concreto es un material versátil, y debido a que se encuentra en todo tipo de construcción su demanda ha aumentado, generando así un incremento en la extracción de agregados, los cuales muchas veces no cumplen con las especificaciones técnicas. Se tuvo por objetivo evaluar comparativamente concretos elaborados con canteras de cerro y de río, para diseños con resistencia a la compresión (f’c) = 175 kg/cm2 y f’c = 210 kg/cm2. Se analizó las propiedades de los agregados tanto de cerro como de río, para calcular la dosificación de los componentes, utilizando la metodología del comité 211 del American Concrete Institute (ACI); luego de la elaboración de las probetas se realizó el curado y posteriormente se realizó los ensayos de resistencia a la compresión a los 7, 14 y 28 días. Se determinó que el concreto elaborado con agregados de río cumplen con los parámetros mínimos de resistencia a la compresión; sin embargo, los agregados en su mayoría no cumplen con la Norma Técnica Peruana (NTP) 400.037 y esto repercute de forma negativa en la resistencia del concreto. Por lo tanto, se recomienda la utilización de los agregados de cerro teniendo en cuenta las respectivas correcciones en el diseño de mezcla para obtener concretos con resistencias requeridas.

Moment and shear transfer between columns and concrete slabs

1990 ◽  
Vol 17 (4) ◽  
pp. 621-628
Author(s):  
Amin Ghali ◽  
Adel A. Elgabry
Keyword(s):  
Shear Strength ◽  
Structural Design ◽  
American Concrete Institute ◽  
Punching Shear ◽  
Vertical Shear ◽  
Concrete Slabs ◽  
Finite Element Analyses ◽  
Shear Transfer ◽  
Flat Slabs ◽  
Punching Failure

Gravity and horizontal forces cause the transfer of vertical shear and moments between concrete flat slabs and their supporting columns. These forces can cause punching failure. Design equations for safety against punching given in the Canadian Standards Association and the American Concrete Institute codes are critically reviewed. It is shown that the equations give in some cases incorrect stresses which do not satisfy equilibrium. A modification is suggested which makes the equations applicable to all cases. The paper also discusses the codes' approach of sharing the resistance to transferred moment between resistances by flexure and by eccentricity of shear, using the coefficient γv. Comparisons are made with the result of finite element analyses. It is concluded that the code equations, with the suggested modification, are adequate, provided that appropriate values are used for the coefficient γv. Key words: columns, connections, flat concrete plates, moments, punching shear, reinforced concrete, shear strength, slabs, structural design.

scholarly journals Optimised Mix Design for Normal Strength and High Performance Concrete Using Particle Packing Method

2011 ◽  
Vol 57 (4) ◽  
pp. 357-371 ◽  
Author(s):  
S. Gopinath ◽  
A. Ramachandra Murthy ◽  
D. Ramya ◽  
Nagesh R. Iyer
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
American Concrete Institute ◽  
Particle Packing ◽  
Mix Design ◽  
Concrete Compressive Strength ◽  
Normal Strength Concrete ◽  
Normal Strength ◽  
Packing Method

Abstract This paper presents the details of optimized mix design for normal strength and high performance concrete using particle packing method. A critical review of mix design methods have been carried out for normal strength concrete using American Concrete Institute (ACI) and Bureau of Indian Standards (BIS) methods highlighting the similarities and differences towards attaining a particular design compressive strength. Mix design for M30 and M40 grades of concrete have been carried out using ACI, BIS and particle packing methods. Optimization of concrete mix has been carried out by means of particle packing method using EMMA software, which employs modified Anderson curve to adjust the main proportions. Compressive strength is evaluated for the adjusted proportions and it is observed that the mixes designed by particle packing method estimates compressive strength closer to design compressive strength. Further, particle packing method has been employed to optimize the ingredients of high performance concrete and experiments have been carried out to check the design adequacy of the desired concrete compressive strength.

Seismic Behavior of Slender HPFRCC Coupling Beams with Limited Transverse Bars

2018 ◽  
Vol 34 (1) ◽  
pp. 77-98 ◽  
Author(s):  
Sang Whan Han ◽  
Jin Wook Kang ◽  
Chang Seok Lee
Keyword(s):  
Seismic Behavior ◽  
High Performance ◽  
American Concrete Institute ◽  
Transverse Reinforcement ◽  
Cement Composites ◽  
Coupling Beams ◽  
Conventional Concrete ◽  
Drift Capacity ◽  
High Performance Fiber ◽  
Reinforced Cement

The objective of this study was to investigate the seismic behavior of slender concrete diagonally-reinforced coupling beams (DRCBs) with an aspect ratio of 3.5 and to explore the possibility of alleviating the reinforcement detail for DRCBs using high-performance fiber-reinforced cement composites (HPFRCCs). For this purpose, slender HPFRCCs and conventional concrete DRCBs with transverse reinforcement spacing of 110 mm, 250 mm, and 500 mm were made and tested. One HPFRCC DRCB specimen was made without transverse reinforcement for comparison purposes. This experimental study shows that the slender HPFRRCC DRCBs with transverse reinforcement spacing of 250 mm have almost the same strength and drift capacity as those of the conventional concrete DRCB with transverse reinforcement spacing of 110 mm, satisfying the requirement of American Concrete Institute ACI 318-14 (2014) building code.

scholarly journals Experimental and Numerical Evaluation of Shear Strength of Directly and Indirectly Loaded Flanged Recycled Self-Compacted Reinforced Concrete Deep Beams

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Thamer Hussein Amer Alhussein ◽  
Jamal Abdul Samad Khudhair
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Ultimate Load ◽  
American Concrete Institute ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Experimental Results ◽  
Experimental Result ◽  
Deep Beams ◽  
Aashto Lrfd

Experimental and numerical investigations of the behavior of directly and indirectly loaded flanged reinforced concrete (RC) deep beams cast with self-compacted concrete (SCC) containing recycled concrete as coarse aggregate (RCA) were conducted in this research. Seventeen RC deep flanged beams were designed to fail in shear. These beams were divided into three groups: twelve indirectly loaded beams without shear reinforcement; three directly loaded beams without stirrups; and two indirectly loaded beams with vertical stirrups. These beams were also classified according to the RCA ratio and shear span-to-effective depth (a/d) ratio, which will be detailed later. The RCA ranged from 0% to 75%, while the a/d ratio was taken as 1.0, 1.35, and 1.7. Experimental results show that the use of RCA reduces the cracking and ultimate capacities, and this finding complies with the conclusions of several research studies in the literature as will be detailed later. It was observed that beams with higher RCA exhibited higher deflection, strain, and crack width. Furthermore, by increasing the a/d ratio, the ultimate load was decreased due to the lower contribution of arch action shear transfer in the beam. A web reinforcement spaced at 100 mm and 50 mm increases the ultimate load by 35% and 48%, respectively. Strut and tie model (STM) presented by the American Concrete Institute (ACI) 318-14 and the American Association of State Highway and Transportation Officials (AASHTO LRFD 2012) was used to predict the ultimate shear capacity of the beams. STM predicted lower beam capacity than the experimental result. The ultimate strength calculated using ACI318-14 and AASHTO LRFD 2012 was on average 38% and 52% lower than the experimental data, respectively, which reflects the conservative nature of this approach. Finally, 3D finite element models were created to investigate the responses of the beams. The FE results showed very good agreement with the experimental data, where FE-predicted shear capacities were on average 9% higher than the experimental results.

Confinement limits for tension lap slices under static loading

1992 ◽  
Vol 19 (3) ◽  
pp. 447-453 ◽  
Author(s):  
T. Rezansoff ◽  
U. S. Konkankar ◽  
Y. C. Fu
Keyword(s):  
Static Loading ◽  
American Concrete Institute ◽  
Concrete Cover ◽  
Transverse Reinforcement ◽  
Lap Splices ◽  
Lap Splice ◽  
Current Limit ◽  
Concrete Confinement ◽  
Bar Diameter ◽  
Concrete Reinforcement

In tension lap splices, the benefit provided to the lap by stirrups placed to intercept longitudinal cracking due to bond splitting action is recognized by the American Concrete Institute code (ACI 318-89) and the design recommendations of ACI Committee 408, on which the American code provisions are partially based. However, a limit exists on the benefit that can be derived from this confinement. In Canada, Canadian Standards Association Standard CAN3 A23.3 M-84 does not directly recognize the confinement benefit provided by stirrups placed along a lap splice. The current study shows that the ACI limit of 1 bar diameter of equivalent concrete cover provided by the transverse reinforcement confinement is too restrictive under static loading. When the concrete cover is small, much larger transverse reinforcement confinement, up to 2-2.5 bar diameters of equivalent concrete cover, can be utilized, in lieu of requiring very long lap lengths. The tests also show that total confinement (actual concrete confinement plus equivalent concrete confinement provided by stirrups) is effective beyond the current limit of 3 main bar diameters, when stirrups are provided. Good performance was found with confinements of 4-4.5 bar diameters, and correspondingly shorter lap splice lengths. Key words: concrete, reinforcement, lap splices, beams, confinement, stirrups, tension, static loading.

Use of Shear Lugs for Anchorage to Concrete

2009 ◽  
Author(s):  
Peter J. Carrato ◽  
Martin Reifschneider
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Design Method ◽  
American Concrete Institute ◽  
Significant Activity ◽  
Lateral Loads ◽  
Nuclear Facilities ◽  
Shear Loads ◽  
Full Scale Tests

Anchoring structures, systems and components to concrete is a significant activity in the design and construction of a nuclear power plant. Early in this decade the Concrete Capacity Design method (CCD) was adopted by the American Concrete Institute (ACI) for use in the structural design for both commercial and nuclear facilities. This design method and associated qualification tests brings new challenges to designing efficient means for anchoring to concrete structures. Although the CCD method provides guidance on many aspects of concrete anchorage there are a few areas, pertinent to nuclear power plant construction, that are not covered or require significant interpretation of the most recent codes. This paper will focus on the design of shear lugs used to resist significant lateral loads. Results from laboratory tests of shear lugs are presented. These full scale tests considered the interaction of tension and shear loads on the performance of shear lug assemblies. Recommendations for the efficient use of shear lugs are provided.

A Life-Cycle Risk-Informed Systems Structured Nuclear Code

2002 ◽  
Author(s):  
Ralph S. Hill
Keyword(s):  
Life Cycle ◽  
American Concrete Institute ◽  
Design Code ◽  
Replacement Decisions ◽  
Plant Operations ◽  
Operations And Maintenance ◽  
Asme Code ◽  
American Society ◽  
Construction Operation ◽  
Design Construction

Current American Society of Mechanical Engineers (ASME) nuclear codes and standards rely primarily on deterministic and mechanistic approaches to design. The design code is a separate volume from the code for inservice inspections and both are separate from the standards for operations and maintenance. The ASME code for inservice inspections and code for nuclear plant operations and maintenance have adopted risk-informed methodologies for inservice inspection, preventive maintenance, and repair and replacement decisions. The American Institute of Steel Construction and the American Concrete Institute have incorporated risk-informed probabilistic methodologies into their design codes. It is proposed that the ASME nuclear code should undergo a planned evolution that integrates the various nuclear codes and standards and adopts a risk-informed approach across a facility life-cycle — encompassing design, construction, operation, maintenance and closure.

scholarly journals Effect of Aggregate Type and Specimen Configuration on Concrete Compressive Strength

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 625 ◽  
Author(s):  
Sherif Yehia ◽  
Akmal Abdelfatah ◽  
Doaa Mansour
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
American Concrete Institute ◽  
Recycled Aggregates ◽  
Concrete Compressive Strength ◽  
Split Tensile Strength ◽  
Standard Size ◽  
Noticeable Effect ◽  
The Difference

In this paper, concrete mixes utilizing two sizes of natural aggregate and two sources of lightweight and recycled aggregates were used to investigate the effect of aggregate type and specimen size and shape on the compressive strength of concrete. In addition, samples from ready-mix concrete producers with different strengths were evaluated using standard size cylinders and cubes. Results were obtained on the 7th, 28th, and 90th day. In addition, flexural strength, split tension, and modulus of elasticity were evaluated on the 28th and 90th day. Statistical analyses were conducted to examine the significance of the difference between the compressive strength values for each two mixes using tests of hypotheses. Moreover, other mechanical properties as a function of compressive strength were discussed and compared to those predicated by the American Concrete Institute (ACI) specifications. Results indicate specimen shape has a noticeable effect on the compressive strength as the Cylinder/Cube ratio on the 90th day was ranging between 0.781 and 0.929. The concrete compressive strength and modulus of elasticity were significantly affected by the aggregate type. The flexural strength and split tensile strength were less affected by the aggregate type, which was also confirmed by the values predicted with the ACI equations.

scholarly journals Experimental Research of Continuous Concrete Beams with GFRP Reinforcement

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Nikola Baša ◽  
Mladen Ulićević ◽  
Radomir Zejak
Keyword(s):  
Experimental Research ◽  
American Concrete Institute ◽  
Rc Structures ◽  
Moment Redistribution ◽  
Continuous Beams ◽  
Load Carrying ◽  
Current Design ◽  
Frp Reinforcement ◽  
Internal Forces ◽  
Gfrp Reinforcement

Continuous beams are often used within RC structures, which are exposed to aggressive environmental impact. The use of the fiber-reinforced polymer (FRP) reinforcement in these objects and environments has a big significance, taking into account tendency of steel reinforcement to corrode. The main aim of these research studies is to estimate ability of continuous beams with glass FRP (GFRP) reinforcement to redistribute internal forces, as a certain way of ductility and desirable behaviour of RC structures. This paper gives the results of experimental research of seven continuous beams, over two spans of 1850 mm length, cross-section of 150 × 250 mm, that are imposed to concentrated forces in the middle of spans until failure. Six beams were reinforced with different longitudinal GFRP and same transverse GFRP reinforcements, and one steel-reinforced beam was adopted as a control beam. The main varied parameters represent the type of GFRP reinforcement and ratio of longitudinal reinforcement at the midspan and at the middle support, i.e., design moment redistribution. The results of the research have shown that moment redistribution in continuous beams of GFRP reinforcement is possible, without decreasing the load-carrying capacity, compared to elastic analysis. The test results have also been compared to current code provisions, and they have shown that the American Concrete Institute (ACI) 440.1R-15 well predicted the failure load for continuous beams with GFRP reinforcement. On the contrary, current design codes underestimate deflection of continuous beams with GFRP reinforcement, especially for higher load levels. Consequently, a modified model for calculation of deflection is proposed.

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