# Tension Stiffening Case Study

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2.1.8.5. Tension stiffening: The term “tension stiffening” is defined as the effect of concrete acting in tension between cracks on the stress of steel reinforcement. At a crack, all the internal tensile force is carried by the reinforcement, whereas between cracks some amount of the tensile force is transferred through bond to the surrounding concrete, which results in a reduction in the reinforcement stresses and strains, and causes the reinforcement strain at uncracked zone to be less than the reinforcement strain at the cracked sections, as shown in figure (2.28). (Allam, Shoukry, Rashad and Hassan, 2013) Figure (2.28): Mean and steel bar stress–strain relationship. (Allam, Shoukry, Rashad and Hassan, 2013) At the end of the nineteenth century, in testing small mortar prisms reinforced with steel bars it had been observed that their tensile load-deformation response was well…show more content…
(Yun, 2010) 2.1.8.5.1. Tension stiffening terms in some codes' equations: 2.1.8.5.1.1. Tension stiffening of normal weight concrete in Eurocode2 (2004): (Eurocode2-2004) gives the following equation for the mean tensile strain (ԑsm-ԑcm) for calculating the crack width of a flexural member, as Eq. (2.32). Where: Kt is the factor expressing the duration of loading: Kt = 0.6 for short term loading and Kt = 0.4 for long term loading; fs is the stress in the tension reinforcement computed on the basis of a cracked section; n is the modular ratio Es/Ec; fcteff is the mean value of tensile strength of the concrete effective at the time when the cracks may first be expected to occur. ρeff = Aceff (effective tension area), is the area of concrete surrounding the reinforcement. The term represents the tension stiffening part. 2.1.8.5.1.2. Tension stiffening of normal weight concrete in (ESS 203): The Egyptian Code (ESS 203-2007) gives the mean strain ԑsm as Eq.