Critical Depth of Normal Cracks in Reinforced Concrete Beams of Rectangular Cross-Section

Abstract

The evaluation of stress state of longitudinal tensile reinforcement is highly important while examining the technical state of under-reinforced concrete structures. The appearance of yield stress in tensile reinforcement could be treated as the start of incipient failure of the flexural structure. The state of tensile reinforcement of flexural reinforced concrete structures could be examined by observing the properties of normal cracks. This paper presents the analysis of the relationship between various parameters of a normal crack during its development. Some elements of fracture mechanics are used for analysis of stress state in flexural reinforced concrete members. The analytical data are compared to the experimental results, and the adjustment functions are proposed for flexural beams of certain cross section shape, dimensions and reinforcing ratio.

Crack Width and Load-Carrying Capacity of RC Elements Strengthened with FRP

“…Hence, a denser cracking and the smaller crack widths are obtained for RC beams strengthened with FRP; the crack widths estimated by the methodology proposed in [19] were used for further analysis. [23,24] proposed crack development model for RC structures, a flexural reinforced concrete element crack has two peaks; one leads to the crack spread toward the beam neutral axis, and the other refers to the tensile reinforcement. The width of the crack apex closer to the neutral axis is critical for further crack spread.…”

“…A wide range of experimental research was conducted by Jokūbaitis et al [23][24][25][26][27][28], and the empirical expression of the critical width of a normal crack tip was derived for flexural RC elements:…”

Flexural behaviour of reinforced concrete members strengthened with prestressed CFRP laminate

“…Different approach was proposed by Jokūbaitis et al (Jokūbaitis and Kamaitis, 2000, Jokūbaitis, 2001, Jokūbaitis, 2009, Jokūbaitis and Juknevičius, 2009, Jokūbaitis et al 2013, Jokūbaitis and Juknevičius, 2013 based fracture mechanics of solids. In accordance with his crack development model for RC structures, the flexural RC element crack has two peaks, one leads to the crack spread toward the beam neutral axis, and the other refers to the tensile reinforcement.…”

“…where h cr and h ct are the crack depth and the depth of the tensile zone above it, respectively; w cr and δ cr.0 are the crack width and the critical width of a normal crack tip respectively. Wide range of experimental research were conducted by Jokūbaitis et al (Jokūbaitis and Kamaitis, 2000, Jokūbaitis, 2001, Jokūbaitis, 2009, Jokūbaitis and Juknevičius, 2009, Jokūbaitis et al 2013, Jokūbaitis and Juknevičius, 2013 and the empirical expression of the critical width of a normal crack tip was derived for flexural RC elements:…”

“…Furthermore, Jokūbaitis related crack parameters to reinforcing steel stress using the methods of fracture mechanics (Jokūbaitis et al 2013, Jokūbaitis and:…”