Reinforced Concrete Design Principles and Structural Systems (Video Notes)

Vocabulary-style flashcards covering structural systems, reinforced concrete behavior, materials, and loading concepts from the lecture notes.

Bearing Wall System

A structural system without a complete vertical load-carrying space frame; bearing or bracing walls resist gravity loads and lateral forces.

Building Frame System

A system with a complete space frame that carries gravity loads; lateral resistance is provided by shear walls or braced frames.

Moment-Resisting Frame System

A frame where gravity loads are carried by the space frame and lateral loads are resisted mainly by flexural action of members and joints.

Dual System

A system where a complete space frame carries gravity loads, while shear walls/braced frames and moment-resisting frames resist lateral loads.

Cantilevered Column System

Structural system that relies on cantilevered columns for lateral resistance.

Undefined System

Structural system not defined in the code.

Non-Building Structural System

Structural system for self-supporting structures other than buildings (elevated tanks, billboards, towers).

R-Seismic Response Modification Factor

Factor used in seismic design to account for energy dissipation and alter design forces.

Q-Seismic Force Overstrength Factor (Omega)

Overstrength factor used in seismic design to account for excess strength beyond design.

Concrete

Structural material of aggregate, cement, and water with high compressive strength but low tensile strength (tensile ≈15% of compressive).

Reinforced Concrete

Concrete in which steel reinforcement is embedded to resist tensile, shear, and some compressive stresses.

Compression & Tension in Structural Members

Concrete resists compression; reinforcing steel resists tension.

Flexural Test

Test measuring the force required to bend a beam and determine resistance to flexing.

Main Reinforcement Bars

Reinforcement bars placed in the tension zone to resist bending (flexure).

Distribution/Intermediate Bars

Secondary bars that help distribute forces and tie the main reinforcement.

Tension Zone

Region in a bending member where tension occurs; location depends on support and loading.

Steel Reinforcements

Steel bars absorb tensile forces and shear; concrete resists compression.

Flexure Cracks

Cracks originating at the maximum moment region when flexural capacity is exceeded.

Shear Cracks

Cracks originating near supports due to insufficient shear capacity.

Grades of Reinforcing Steel

Grades such as Grade 75 (500 MPa) and Grade 80 (550 MPa); color markings identify grade.

Concrete Cover

Distance from exposed concrete surface to the reinforcing bar; protects steel.

Spacing Limits for Reinforcements

Specified maximum spacing (noted as 25 mm in the notes).

Balanced Design

Design where maximum stresses in concrete and steel occur simultaneously at ultimate load.

Under-Reinforced Design

Steel reinforcement is less than balanced; steel yields before concrete failure.

Ultimate Strength Design (USD)

Design method where concrete behavior is considered up to ultimate strength (non-linear elastic analysis).

Working Stress Design (WSD)

Linear elastic design method; behavior is considered up to the proportional limit.

Slabs

Flat horizontal panels that carry gravity loads and act as diaphragms to transfer lateral loads.

One-Way Floor System

Slab that delivers load to supports by one-way action; bends in the short span.

Two-Way Floor System

Slab that delivers load by two-way action; load is transferred in two directions.

Beams

Horizontal members that carry vertical loads; designed to resist bending moments; shear may govern when short or heavily loaded.

Flexure & Shear Cracks

Flexure cracks originate from bending; shear cracks originate near supports where shear demand is high.

Columns

Vertical members that resist axial compressive loads.

Aggregates

Materials making up about 70–75% of concrete volume (sand, crushed stone, pebbles) that provide volume and stability.

Coarse Aggregate

Particles retained on 4.75 mm sieve; coarser aggregate typically more economical.

Fine Aggregates

Particles passing No. 4 sieve; fill voids and improve workability.

Portland Cement

Cement varieties (Ordinary, Rapid Hardening, Low Heat, Sulfate, High Alumina) per ASTM; binds aggregates.

Water-Cement Ratio

Ratio affecting concrete strength; lower ratios generally increase strength.

Concrete Mixing Principles

Workability, strength, durability, and economy guide mixing.

Concrete Compressive Strength f'c

Strength of hardened concrete under compression; measured by testing cylinders.

Concrete Strength Values

Residential ~2500 psi; commercial ~4000 psi; some applications >10,000 psi.

Reinforcing Steel Bars

Steel bars used to reinforce concrete; largely linear elastic, with yield strength guiding design.

Prestressed Steel

High-tension cables used to prestress concrete to counteract tensile stresses.

Elastic Limit

Point at which material returns to original shape after unloading.

Ultimate Compressive Strength

Maximum stress on the stress–strain curve for concrete.

Ultimate Tensile Strength

Maximum tensile stress a material can withstand.

Yield Point

Point where constant stress is applied but strain continues to increase.

Structural Loadings

Dead loads, Live loads, Wind loads, Seismic loads considered in design.

Wind Loads

Horizontal forces due to wind; typically less critical for low-rise buildings due to diaphragm continuity.

Seismic Loads

Forces from an earthquake; primarily horizontal movement considered in design.

Performance-Based Design

Design approach that controls displacements within acceptable limits under service, factored, and environmental loading.