Untitled Quiz

Study Notes

Concrete is a mixture of aggregates (sand, gravel, crushed rock), cement, and water, forming a rock-like mass.
Admixtures may be added to enhance properties like workability, durability, and hardening time.
Reinforced concrete combines concrete and steel, improving tensile strength.

High compressive strength per unit cost compared to other materials.
Excellent resistance to fire and water, making it ideal for wet environments.
Provides structural rigidity, resulting in durable constructions.
Requires minimal maintenance, leading to low long-term costs.
Offers a long service life, outlasting many alternative materials.
Economically viable for various applications, such as footings and floor slabs.
Versatile in casting shapes, capable of forming complex structures.
Utilizes inexpensive local materials, enhancing cost-effectiveness.
Requires less skilled labor for erection compared to materials like structural steel.

Low tensile strength necessitates the use of reinforcing materials.
Costly forms are required to shape concrete until it hardens; shoring may also be needed for structural support.
Heavy weight can hinder long-span structures, influencing bending moments.
Large member sizes due to low strength per unit volume affect tall buildings and span design.
Property variability can occur due to inconsistencies in mixing, proportioning, and curing processes.

Curing involves submerging concrete in water to prevent moisture loss and cracking.
Maximum strength is ideally achieved after 28 days of curing.

Stress (σ) is the applied force (F) divided by area (A): σ = F / A.
Strain (ε) is the change in length (ΔL) over the original length (Lo): ε = ΔL / Lo.
Hooke’s Law states that stress is proportional to strain within the proportionality limit.
Elastic limit allows material to return to original shape post-load removal.
Ultimate compressive strength is the maximum stress endured before failure.

Establish technical standards and requirements for structural design.
The modulus of elasticity for normal weight concrete (NWC) is given by Ec = 4700λfc (in MPa), where λ=1.00 for NWC and λ=0.75 for light weight concrete (LWC).

Represents the load-carrying capacity of uncracked concrete.
Common fc’ values include 17 MPa (lowest per NSCP 2015), 21 MPa (3 ksi), 28 MPa (4 ksi), and 34 MPa (5 ksi).

Working Stress Design (WSD): Assumes linear elastic behavior up to the proportionality limit.
Ultimate Stress Design (USD): Considers non-linear elastic behavior up to ultimate strength.

Longitudinal Bars (Rebars):
- Plain bars have a smooth surface.
- Deformed bars feature ridges for better concrete anchoring.
Pre-stressed Steel: Utilizes high-tension cable wires to enhance concrete strength.
Structural Steel Shapes: Includes wide flange, angle bars, C sections, rectangular, and tubular shapes.