Control of cracking - Concrete Structures: Stresses and Deformations - page 406

or shrinkage is restrained by the wall footings. Another example where simi-
lar crack patterns can occur is in bridge superstructures, 10 where parts of the
cross-section are cast separately, using longitudinal casting joints (for
example parapets or overhanging parts of the deck cast separately to the
main deck).

11.11 General
This chapter discusses the parameters that in

uence crack width and gives
equations to determine the steel area of bonded reinforcement required to
limit the width of cracks to a speci

fl

ed value. The analysis is approximate
because it includes empirical parameters: s rm and

fi

ζ to predict crack spacing

and to account for tension sti ζ

are to be determined from codes (some code expression are given in Appendix
E and Equation (8.45).

ff ening. The empirical coe cients for s rm and

Notes
1 This example is based on: Elbadry, M.M. (1988), Serviceability of Reinforced
Concrete Structures , Ph.D. thesis, Department of Civil Engineering, University of
Calgary, Calgary, Canada, 294 pp.
2 Equation (11.1) is derived from experiments reported in: Jaccoud, J.P. (1987),
Armature minimale pour le contrôle de la fissuration des structures en béton , Ph.D.
thesis, Département de Génie Civil, École Polytechnique Fédérale de Lausanne,
Lausanne, Switzerland, 195 pp.
3 Equation (11.11) is derived from experiments reported in Jaccoud (1987); see
reference mentioned in Note 2, above.
4 See reference mentioned in Note 2, above.
5 A suggested equation can also be found in: Department of Transport Highways
and Trac (1987), Department Advice Note BA24/87, Early Thermal Cracking of
Concrete , 16 pp., DOE/DTp Publication Sales Unit, Bldg. 1, Victoria Rd., 5,
Ruislip, Middlesex HA4 0NZ, UK.
6 Schiessl, P. (1985), Mindestbewehrung zur Vermeidung klaffender Risse , Institut fur
Betonstahl und Stahlbetonbau, Munich, Bericht 284.
7 Beeby, A.W. (1983), 'Cracking, cover and corrosion of reinforcement', Concrete
International , 28 , (2), Feb., pp. 35-40.
8 See Jaccoud, J.-P, Charif, H. and Farra, B. (1993), Cracking Behaviour of HSC
Structures and Practical Considerations for Design , Publication No. 139, IBAP,
Swiss Federal Institute of Technology, Lausanne, Switzerland.
9 ACI 318-89 Building Code Requirements for Reinforced Concrete Institute,
Farmington Hills, Michigan 48333-9094. The clause referred to here has been
dropped out in subsequent issues of the Code.
10 See reference mentioned in Note 5, above.