Shear, Torsion, Bond, and Slabs in RCC

Vocabulary practice flashcards covering structural engineering topics including shear stress distribution, torsional failure modes, bond mechanisms, and slab classification from the lecture notes.

Horizontal Shear Stress

The stress created by the inequality of stresses across adjacent sections that produces a tendency in each fiber to slide over the lower one.

Shear Stress Equation ($q$)

$q = \frac{V(Ay)}{Ib}$, where $V$ is the shear force, $Ay$ is the moment of area above the considered plane, $I$ is the moment of inertia, and $b$ is the breadth.

Neutral Axis ($NA$) in RC Beams

The location in a rectangular cross-section where the area $A$ becomes maximum and therefore the shear stress ($\tau$) is at its maximum ($\tau_{max}$).

True Shear Stress ($q$)

Calculated as $q = \frac{V}{ab}$, where $a$ is the lever arm represented as $a = d - \frac{n}{3}$.

Nominal Shear Stress ($\tau_v$)

The stress calculated using the formula $\tau_v = \frac{V_u}{bd}$ to determine shear requirements.

Diagonal Tension

Tensile stress developed along the diagonal plane of a block subjected to shear; if the material is weak in tension, it splits along this plane.

Diagonal Compression

Compressive stress developed along a diagonal plane due to shear; failure occurs by crushing if the material is weak in compression.

Shear Strength of Concrete ($\tau_c$)

The shear resistance of concrete derived from the uncracked compression zone, aggregate interlock, and the dowel action of longitudinal reinforcement.

Torsion

The twisting of an object due to an applied torque or twisting moment along the plane of the cross-section.

Warping

A phenomenon in non-polar sections under torsion where plane sections do not remain plane but turn into curves.

Primary Torsion

Also known as equilibrium torsion, it is required to maintain equilibrium in a structure and must be considered in design.

Secondary Torsion

Also known as compatibility torsion, it is developed to maintain compatibility between members; design for this is optional.

Skew Bending Theory

The theory upon which codal provisions for the design of rectangular beams under combined flexure and torsion are based.

Mode 1 Failure

A failure mode in combined flexure and torsion where bending is predominant and concrete crushes at the top.

Equivalent Shear ($V_e$)

$V_e = V_u + 1.6 \times \frac{T_u}{b}$, used when designing for combined shear and torsion.

Bond in RCC

The adhesion between reinforcing steel and surrounding concrete that enables the transfer of axial force and ensures strain compatibility.

Flexural Bond

Bond stress that arises in flexural members due to the variation of bending moments, which causes a variation in axial force along the reinforcing bar.

Development Length ($L_d$)

The minimum length of a reinforcing bar ($L_d = \frac{\theta \times \text{stress}}{4 \tau_{bd}}$) required to transfer the force in the bar to the surrounding concrete by bond.

One-way Slab

A slab supported on two opposite sides, or on four sides where the ratio of longer span to shorter span ($l_y/l_x$) is greater than 2.

Two-way Slab

A slab panel supported on all four sides where the length to width ratio ($l_y/l_x$) is less than or equal to 2, primarily bending in two directions.

Rankine-Grashoff Theory

A theory used to explain the behavior of two-way slabs by considering the deflection compatibility of strips in orthogonal directions.

Restrained Slabs

Slabs where the corners are prevented from lifting, resulting in the development of torsional moments at the corners.