Introduction to Reinforced Concrete Design

Flashcards covering fundamental concepts, material properties, code specifications, spacing rules, and load classifications in reinforced concrete design.

What is the specified modulus of elasticity of steel ($E_s$) given in the design notations?

$$200,000\,\text{MPa}$$

What proportion of concrete's total volume is typically occupied by aggregates?

Aggregates occupy approximately three-fourths ($\frac{3}{4}$) of the concrete volume.

How is fine aggregate defined based on sieve size?

Fine aggregate is defined as any aggregate material that passes a No. 4 sieve (approximately $6\,\text{mm}$ in size).

What is the minimum compressive strength requirement for mortar test cubes mixed with non-potable water?

Mortar test cubes made with non-potable water must have 7-day and 28-day strengths equal to at least $90\%$ of similar specimens made with potable water.

What is the function of the ribbed projections rolled onto deformed reinforcing bars?

To provide better bonding between the concrete and the steel.

What building code regulates the design and construction of reinforced concrete structures in the Philippines?

The National Structural Code of the Philippines (NSCP 2015), published by the Association of Structural Engineers of the Philippines, Inc. (ASEP) and adapted from ACI 318-14M.

What is the minimum specified compressive strength ($f'_c$) for general normalweight concrete under NSCP 2015 Table 419.2.1.1?

$$17\,\text{MPa}$$

What formula is used to calculate the modulus of elasticity ($E_c$) for normal weight concrete according to NSCP 2015?

$E_c = 4700\sqrt{f'_c}$ (in $\text{MPa}$)

What is the minimum clear spacing requirement for parallel non-prestressed reinforcement placed in a horizontal layer?

The clear spacing must be at least the greatest of $25\,\text{mm}$, $d_b$, and $\frac{4}{3}d_{agg}$.

What is the minimum clear spacing required for longitudinal reinforcement in columns, pedestals, and struts?

Clear spacing between bars must be at least the greatest of $40\,\text{mm}$, $1.5d_b$, and $\frac{4}{3}d_{agg}$.

What is the maximum number of parallel reinforcing bars allowed to be bundled together as a unit?

A maximum of four bars in any one bundle.

What size restriction applies to bundled reinforcing bars inside beams according to NSCP 2015?

Bars larger than $36\,\text{mm}$ diameter ($d_b$) shall not be bundled in beams.

How far must individual bar terminations within a bundle be staggered when terminated inside flexural members?

They must terminate at different points with at least a $40d_b$ stagger.

By what percentages is the development length of individual bars increased for 3-bar and 4-bar bundles?

The development length is increased by $20\%$ for a 3-bar bundle and $33\%$ for a 4-bar bundle.

How is a unit of bundled bars treated when determining equivalent diameter ($D$) for spacing and cover limits?

It is treated as a single bar with an area equivalent to that of the total bundle and a centroid coinciding with that of the bundle.

What value may be used for the yield strain ($\varepsilon_{ty}$) of Grade 280 deformed reinforcement?

$$\varepsilon_{ty} = 0.002$$

What is the specified unit weight of concrete used when determining dead loads?

$$23.54\,\text{kN/m}^3$$

What is the primary difference between Dead Loads and Live Loads?

Dead loads are of constant magnitude and remain in one fixed position, whereas live loads can change in magnitude and position and are generally induced by gravity.

According to the NSCP design tables for strain control, what is the strength reduction factor ($\phi$) for tension-controlled sections?

$$\phi = 0.90$$