Lateral Instablity of Reinforced Concrete Beams Under Uniform Bending Moments

Slenderness in Steel Fibre Reinforced Concrete Long Beams

“…All documented test findings on slender reinforced rectangular beams (which collapsed by buckling) are taken into account for the aim of validating the suggested formulation for Mbcr and comparing it to concepts found in the literature. The proposed formulation was validated by the experimental investigations undertaken by Revathi & Menon [6], Girija & Menon [8] and Sant & Bletzacker [9] and Massey [10].The published literature validated that both under-reinforced and over-reinforced beams are found to be suitable for the suggested technique.…”

“…The 'flexural resistance factor' R for a beam section of width b and having an effective depth d) is R = Muf / (bd 2 ); and α, β are the 'effective flexural rigidity' and 'torsional rigidity coefficients' that are a function of fracturing and and tension stiffening, respectively. The suggested formula for Mbcr was verified using seven tests performed by Revathi & Menon [6], three tests devised by Sant & Bletzacker [9], and eleven tests designed by Massey [10]. As many as eight beams that Revathi & Menon [7] tested collapsed by buckling actually failed in the flexural tension mode, despite the fact that the flexural capacity in majority of these cases was lowered due to slenderness as stated by Girija & Menon [8].…”

“…Revathi and Menon [7] provided a revised formulation that included modified formulas for effective lateral flexural rigidity (𝐵 𝑒𝑓𝑓 ) and effective torsional rigidity (𝐾 𝑒𝑓𝑓 ). In the current research, a similar technique is used to calculate 𝐵 𝑒𝑓𝑓 and𝐾 𝑒𝑓𝑓 , with the gross cross section for flexural and torsional stiffness of UN -cracked concrete sections being as follows: (10) 𝐾 𝑒𝑓𝑓 = β𝐺 𝑐 𝐵 3 𝐷 3 (11) In order to arrive at highly realistic estimations of 𝐵 𝑒𝑓𝑓 and 𝐾 𝑒𝑓𝑓 , and therefore Mbcr, certain modifications have often been made in the research by Girija and Menon [8]. The actual drop in depth (𝑑 𝑒𝑞𝑣 ) due to bending fracturing with respect to the major axis is accounted for the flexural stiffness coefficient (α).…”