RCC and Prestress Concrete Review Flashcards

Comprehensive vocabulary flashcards covering Working Stress Method (WSM), Limit State Method (LSM), design assumptions, component analysis (beams, slabs, columns, footings), and Prestress Concrete based on the provided notes and IS 456:2000/IS 1343:2012 standards.

Working Stress Method (WSM)

A traditional or oldest design method based on the Elastic Theory, where it is assumed that concrete and steel behave elastically and return to their original shape when loads are removed.

Modular Ratio ($m$)

In WSM, it is calculated as $m = \frac{280}{3\times\text{cbc}}$, where $\text{cbc}$ is the permissible compressive stress in concrete; it partially accounts for long-term effects like creep.

Transformed Section

The concrete section plus the area of reinforcement transformed on the basis of the modular ratio.

Under-reinforced Section

A section in which the steel reaches its permissible stress ($\text{st}$) first ($x_a < x_c$), providing warning before failure through larger deflections.

Over-reinforced Section

A section where the concrete reaches its permissible stress ($\text{cbc}$) first ($x_a > x_c$); failure is sudden (compression failure) without warning and is generally undesirable.

Characteristic Strength ($f_{ck}$)

The strength of material below which not more than $5\%$ of the test results are expected to fall.

Characteristic Load ($Q_{ck}$)

The load which has a $95\%$ probability of not being exceeded during the design life of the structure.

Limit State of Collapse

A safety-related assessment in LSM that ensures the structure is designed to withstand all loads liable to act on it in terms of flexure, shear, torsion, and compression.

Limit State of Serviceability

Design requirements focusing on the acceptable limits for deflection, cracking, vibration, and fire resistance before failure occurs.

Partial Safety Factor ($\gamma_m$)

Values used to underestimate material strength for safe design; in LSM, it is $1.5$ for concrete and $1.15$ for steel.

Maximum Strain in Concrete

The maximum strain in concrete at the outermost compression fiber is assumed to be $0.0035$ for members subjected to bending at the Limit State of Collapse.

Deep Beam

Defined as a beam where the ratio of effective span to depth ($l_{eff}/D$) is less than $2$ for simply supported beams or less than $2.5$ for continuous beams.

Nominal Shear Stress ($\tau_v$)

The shear stress calculated as $\tau_v = \frac{V_u}{bd}$ for beams of uniform depth, where $V_u$ is the factored shear force.

Development Length ($L_d$)

The minimum length of reinforcement required to be embedded in concrete to develop the design stress through bond ($L_d = \frac{\phi \times 0.87f_y}{4\tau_{bd}}$ for LSM).

One-way Slab

A rectangular slab supported on opposite edges or where the aspect ratio of longer span to shorter span ($l_y/l_x$) is greater than $2$, resultantly bending primarily in one direction.

Two-way Slab

A rectangular slab supported on all four edges where the aspect ratio ($l_y/l_x$) is less than or equal to $2$, with bending comparable in two orthogonal directions.

Flat Slab

A reinforced concrete slab supported directly by columns without beams or girders, often using drop panels or column capitals to resist punching shear.

Slenderness Ratio ($\lambda$)

The ratio of the effective length of a compression member to its least lateral dimension ($l_{eff}/b$).

Short Column

A column where both slenderness ratios ($l_{ex}/D$ and $l_{ey}/b$) are less than $12$; otherwise, it is considered a slender or long column.

Minimum Eccentricity ($e_{min}$)

Applied to columns to account for accidental loading, calculated as the maximum of $\frac{L}{500} + \frac{D}{30}$ or $20\,mm$.

Pretensioning

A method of prestressing where tendons are stretched first before concrete is poured into the mold; the prestress is transferred to concrete through bond.

Post-tensioning

A method where concrete is cast first (with ducts) and tendons are stretched after the concrete hardens; the prestress is transferred via end anchorages.

Elastic Shortening Loss

A loss of prestress occurring when the concrete is compressed by the tendons, causing the tendons to shorten along with the concrete.

Creep Coefficient ($\theta$)

The ratio of ultimate creep strain to elastic strain, used to calculate long-term losses in prestress concrete.

Concordant Cable Profile

A special cable profile in prestressed concrete that produces no secondary reactions or secondary moments at the supports.