Secant Method

This method is also referred as the tangent, secant or chord modulus for the line drawn from the shear stress-shear strain curve at 5% (1/20) and 33% (1/3) of the maximum compressive shear stress. This region usually lies well within reasonably linear part of the curve. Lower part of the curve, representing a straight region being associated with closing up the interfaces between mortar and units is ignored, as they normally close up due to self weight in real structures. Calculations for Ec are as follows.

Ec = ∆ Shear Stress / ∆Shear Strain

∆ Shear Stress = (Shear stress corresponding to 1/3 of the compressive strength) - (Shear stress corresponding to 1/20 of the compressive strength)

∆ Shear Strain = Difference of the Shear strain at corresponding values of Shear stress.

Dear Debojit Sarker

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