Capítulo II: Conceptos Generales
2.3 Vulnerabilidades, Amenazas y Riesgos de la Información
2.3.4 Clasificación de riesgos, amenazas y vulnerabilidades
IS 8043 : 1991 — Specification for hydrophobic Portland cement (second revision);
IS 12600 : 1989 — Specification for low heat Portland cement;
IS 12330 : 1988 — Specification for sulphate resisting Portland cement;
IS 8042 : 1978 — Specification for Portland white cement (first revision);
IS 8043 : 1991 — Specification for hydrophobic Portland white cement (second revision);
IS 6452 : 1989 — Specification for high alumina cement for structural use (first revision);
IS 6909 : 1990 — Specification for supersulphated cement (first revision);
IS 4031 : 1988 — Methods of physical tests for hydraulic cement;
Standards on Aggregate, Water and Admixtures
IS 383 : 1970 — Specification for coarse and fine aggregates from natural sources for concrete (second revision);
IS 9142 : 1979 — Specification for artificial lightweight aggregates for concrete masonry units;
IS 2386 (Parts 1–8) — Methods of tests for aggregate for concrete;
IS 3025 (Parts 17–32) — Methods of sampling and test (physical and chemical) for water and waste water;
IS 9103 : 1999 — Specification for admixtures for concrete (first revision);
IS 3812 : 1981 — Specification for flyash for use as pozzolana and admixture (first revision);
IS 1344 : 1981 — Specification for calcined clay pozzolana (second revision);
Standards on Concrete
IS 10262 : 1982 — Recommended guidelines for concrete mix design;
IS 7861 (Part 1) : 1975 — Code of Practice for extreme weather concreting: Part 1 — Recommended practice for hot weather concreting;
IS 4926 : 1976 — Ready-mixed concrete (first revision);
IS 1199 : 1959 — Methods of sampling and analysis of concrete;
IS 516 : 1959 — Methods of tests for strength of concrete;
IS 5816 : 1999 — Method of test for splitting tensile strength of concrete cylinders (first revision);
IS 3370 (Part 1) : 1965 — Code of Practice for the storage of liquids: Part 1 — General
IS 1343 : 1980 — Code of Practice for Prestressed Concrete (first revision);
Standards on Reinforcing Steel
IS 432 (Part 1) : 1982 — Specification for mild steel and medium tensile steel bars for concrete reinforcement (third revision);
IS 1786 : 1985 — Specification for high strength deformed steel bars for concrete reinforcement (third revision);
IS 1566 : 1982 — Specification for hard-drawn steel wire fabric for concrete reinforcement (second revision);
IS 2062 : 1999 — Steel for general structural purposes- Specification (Fifth revision);
IS 1608 : 1995 — Mechanical testing of Metals – Tensile testing (second revision).
REVIEW QUESTIONS
2.1 What are the types of cement that are suitable for (a) mass concreting, (b) resistance to sulphate attack?
2.2 How can the development of strength and heat of hydration be controlled in cement manufacture?
2.3 Can the use of excessive cement in concrete be harmful?
2.4 What do the terms stiffening, setting and hardening mean, with reference to cement paste?
2.5 What is the basis for deciding the maximum size of coarse aggregate in concrete work?
2.6 What is meant by segregation of concrete? Under what circumstances does it take place?
2.7 What is meant by workability of concrete, and how is it measured?
2.8 Discuss the role of water in producing ‘good’ concrete.
2.9 Mention the different types of ‘admixtures’ and their applications.
2.10 (a) Define characteristic strength. (b) Determine the ‘mean target strength’
required for the mix design of M25 concrete, assuming moderate quality control.
2.11 Enumerate the steps involved in the Indian Standard method of mix design.
2.12 Why is the cube strength different from the cylinder strength for the same grade of concrete?
2.13 Can concrete be assumed to be a linear elastic material? Discuss.
2.14 Distinguish between static modulus and dynamic modulus of elasticity of concrete.
2.15 Discuss the variations of longitudinal, lateral and volumetric strains that are observable in a typical uniaxial compression test on a concrete prism.
2.16 Why does the Code limit the compressive strength of concrete in structural design to 0.67 fck , and not fck?
2.17 Is the modulus of rupture of concrete equal to its direct tensile strength?
Discuss.
2.18 The standard flexure test makes use of a ‘third-point loading’. Is this necessary? Can a single point load at midspan be used as an alternative?
2.19 Why is it not possible to determine the shear strength of concrete by subjecting it to a state of pure shear?
2.20 What is the advantage of confinement of concrete? Give suitable examples to illustrate your point.
2.21 What does ‘creep of concrete’ mean? Is creep harmful or beneficial?
2.22 How is it that the deflection of a simply supported reinforced concrete beam increases due to shrinkage of concrete?
2.23 Consider a simple portal frame (with fixed base) made of reinforced concrete.
Sketch the approximate shape of the deflection curve caused by (a) a uniform shrinkage strain, (b) a uniform temperature rise.
2.24 Consider the temperature gradient across the shell thickness of a reinforced concrete chimney (with tubular cross-section). Where would you provide reinforcing steel to resist tensile stresses due to the effect of temperature alone (caused by the emission of hot gases): close to the outer circumference or close to the inner circumference? Justify your answer.
2.25 How would you define ‘durable concrete’? Discuss the ways of ensuring durability.
2.26 Cite two examples each for the five categories of ‘environmental exposure’
described in the Code.
2.27 Describe the main factors that affect the permeability of concrete.
2.28 Discuss briefly the factors that lead to corrosion of reinforcing steel.
2.29 What steps can a designer adopt at the design stage to ensure the durability of a reinforced concrete offshore structure?
2.30 What is meant by strain hardening of steel? How is it related to the grade of reinforcing steel?
2.31 What is meant by cold-working of mild steel? How does it affect the structural properties of the steel?
2.32 What is Bauschinger effect? Where is it relevant?
REFERENCES
2.1 Neville, A.M., Properties of Concrete, Second edition, Pitman Publishing Co., London, 1973.
2.2 Mehta, P.K. and Monteiro, P.J.M., Concrete: Microstructure, Properties and Materials, Indian edition, Indian Concrete Institute, Chennai, 1997.
2.3 Neville, A.M. and Brooks, J.J., Concrete Technology, ELBS edition, Longman, London, 1990.
2.4 — Design of Concrete Mixes, Special Publication SP:23, Bureau of Indian Standards, New Delhi, 1982.
2.5 Rao, P.S. and Aravindan, P.K., Concrete Mix Design Practice — Need for a Fresh Approach, Indian Concrete Journal, May 1990, pp 234–237
2.6 Price, W.H., Factors Influencing Concrete Strength, Journal ACI, Vol. 47, Feb. 1951, pp 417–432.
2.7 — Guide for Use of Admixtures in Concrete, ACI Committee Report 212.2 R-81, Am. Conc. Inst., Detroit, Michigan, USA, 1981.
2.8 — Cement and Concrete Terminology, ACI (Committee 116) Special Publication SP-19, Am. Conc. Inst., Detroit, Michigan, USA, 1967.
2.9 Ellingwood, B. and Galambos, T.V. and MacGregor, J G. and Cornell, C.A., Development of a Probability Based Load Criterion for American National Standard A58, Special Publication No.°577, National Bureau of Standards, Washington D.C., 1980 .
2.10 — Standard Practice for Selecting Proportions for Normal, Heavyweight and Mass Concrete, ACI Standard 211.1–81, Am. Conc. Inst., Detroit, Michigan, USA, 1981.
2.11 — Standard Practice for Selecting Proportions for Structural Lightweight Concrete, ACI Standard 211.2–81, Am. Conc. Inst., Detroit, Michigan, USA, 1981.
2.12 — Standard Practice for Selecting Proportions for No-Slump Concrete, ACI Standard 211.3–75 (revised), Am. Conc. Inst., Detroit, Michigan, USA, 1980.
2.13 Teychenne, D.C., Franklin, R.E., Erntroy, H.C., Design of Normal Concrete Mixes, Dept. of Environment, Her Majesty’s Stationary Office, London, 1975.
2.14 Kesler, C.E., Hardened Concrete Strength, ‘Tests and Properties of Concrete’, ASTM Special Testing Publication No. 169–A, Am. Soc. for Testing and Materials, 1966, pp 144–159.
2.15 Hsu, T.T.C. et al, Microcracking of Plain Concrete and the Shape of the Stress-Strain Curve, Journal ACI, Vol. 60, Feb. 1963, pp 209–223.
2.16 Kupfer, H., Hilsdorf, H.K. and Rüsch, H., Behaviour of Concrete Under Biaxial Stresses, Journal ACI, Vol. 66, Aug. 1969, pp 655–666.
2.17 Hognestad, E., Hanson, N.W. and McHenry, D., Concrete Stress Distribution in Ultimate Strength Design, Journal ACI, Vol. 52, Dec. 1955, pp 455–479.
2.18 Sinha, B.P., Gerstle, K.H. and Tulin, L.G., Stress-Strain Relationships for Concrete Under Cyclic Loading, Journal ACI, Vol. 61, Feb. 1964, pp 195–
211.
2.19 ACI Committee 439, Effect of Steel Strength and Reinforcement Ratio on the Mode of Failure and Strain Energy Capacity of R.C. Beams, Journal ACI, Vol. 66, March 1969, pp 165–173.
2.20 Rüsch, H, Researches Towards a General Flexural Theory for Structural Concrete, Journal ACI, Vol. 57, July 1960, pp 1–28.
2.21 — Building Code Requirements for Reinforced Concrete, ACI Standard 318–
89, Am. Conc. Inst., Detroit, Michigan, USA, 1989.
2.22 Rao, P.S. and Menon, D., Ultimate Strength of Tubular R C Tower Sections Under Wind Loading, Indian Concrete Journal, Feb. 1995, pp 117–123.
2.23 Wright, P.J.F., Comments on an Indirect Tensile Test on Concrete Cylinders, Magazine of Concrete Research, No. 20, 1955, p. 87.
2.24 Tasuji, M.E., Slate, F.O. and Nilson, A.H., Stress-Strain Response and Fracture of Concrete in Biaxial Loading, Journal ACI, Vol. 75, July 1978, pp 306–312.
2.25 Bresler, B. and Pister, K.S., Strength of Concrete Under Combined Stresses, Journal ACI, Vol. 55, Sept. 1958, pp 321–345.
2.26 Richart, F.E., Brandtzaeg, A. and Brown, R.L., A Study of the Failure of Concrete Under Combined Stresses, Univ. of Illinois Engineering Experimental Station, Bulletin No. 185, 1928.
2.27 Gerstle, K.H. et al,. Strength of Concrete Under Multi-axial Stress States, ACI Publication SP–55, Am. Conc. Inst., Detroit, Michigan, USA, 1978, pp 103–
131.
2.28 Park, R. and Paulay, T., Reinforced Concrete Structures, John Wiley & Sons, Inc., New York, 1975.
2.29 ACI Committee 209, Prediction of Creep, Shrinkage and Temperature Effects in Concrete Structures, SP–27, Am. Conc. Inst., Detroit, Michigan, USA, 1971, pp 51–93.
2.30 CEB-FIP, International Recommendations for the Design and Construction of Concrete Structures, Comité Européen du Béton-Fédération Internationale de la Précontrainte, Paris, 1970.
2.31 Gouthaman, A. and Menon, D., Increased Cover Specifications in IS 456 (2000) – Crack-width Implications in RC Slabs, Indian Concrete Journal, Sept. 2001, pp 581–586.
2.32 ACI Committee 201, Guide to Durable Concrete, Journal ACI, Vol. 74, 1977, pp 573–609.
2.33 — Explanatory Handbook on Indian Standard Code of Practice for Plain and Reinforced Concrete (IS 456:1978), Special Publication SP:24, Bureau of Indian Standards, New Delhi, 1983.
2.34 Purushothaman, P., Reinforced Concrete Structural Elements — Behaviour, Analysis and Design, Tata McGraw Hill Publication Co. Ltd., New Delhi, 1984.