Reinforced Concrete Design CE 337 - Lateral Loads, Floor Systems, Vertical Framing, Design Philosophies, and Limit State Method

Flashcards cover lateral load resisting systems, floor system types, vertical framing, design philosophies (WSM, ULM, LSM), and limit state method concepts including strengths, safety factors, and load combinations.

What are the components of the lateral load resisting mechanism in reinforced concrete buildings?

Lateral loads are resisted and transmitted through cladding, floor diaphragms, and frame or shear wall systems.

Give examples of lateral loads mentioned for RC buildings.

Earthquakes, wind, water pressure, soil pressure, etc.

What are the two main floor system categories discussed in the notes?

Wall-supported slab system and beam-supported slab system.

What is a flat plate system in floor design?

A floor system with minimal drop panels or columns-slab connections, suitable for low shear and hogging moments.

What advantage does a flat slab system have over a flat plate system?

Increased shear and hogging moment resistance at the columns, allowing higher loads and longer spans.

In a wall-supported slab system, how are loads transmitted and what bending directions can occur?

Loads are transmitted to walls; slab bending can be unidirectional or bidirectional.

In a beam-supported slab system, what are the key structural elements and load path?

Slab, beams, and columns; loads are transmitted via beams to walls or columns.

What are the components of vertical framing systems?

Columns, transfer girders, walls (bearing walls for gravity, shear walls for lateral), and suspenders.

What is the role of transfer girders in vertical framing?

They are required for large column-free spaces in lower floors.

What does 'tube action' refer to in lateral load resisting systems?

A framed-tube action with closely spaced outer columns and deep beams, producing high flexural rigidity.

What are the primary lateral load resisting system types?

Frames, shear walls, and tube action (frame-wall interaction).

How do frame and shear wall actions interact in a combined system?

Frames restrain wall deformation in upper stories; shear walls restrain frame deformation in lower stories.

What are the three design philosophies covered in these notes?

Working Stress Method (WSM), Ultimate Load Method (ULM), and Limit State Method (LSM).

In the Working Stress Method, how are stresses treated under working loads?

Stresses are linear elastic with permissible stresses well below material strength; overloads are accounted via strength-permissible-stress ratios.

How is safety defined in the Working Stress Method?

gamma = sigmamax / sigmawsm (ratio of material strength to permissible stress).

What characterizes the Ultimate Load Method (ULM) regarding loads and behavior?

Loads are multiplied by load factors to account for ultimate loads and nonlinear behavior; nonlinear stress-strain is considered.

What is a key advantage of the Ultimate Load Method over WSM?

It allows slender sections and provides a more economical design by accounting for nonlinear behavior.

What are the two main limit state categories in design?

Ultimate limit state and Serviceability limit state.

What differentiates Ultimate Limit State from Serviceability Limit State?

ULS covers strength and stability (e.g., overturning, buckling); SLS covers serviceability aspects like deflection, crack width, and vibration.

What is f_ck in concrete design?

Characteristic strength of concrete (cube test samples).

What is f_cm in the code context?

Mean (average) strength of concrete; fcm = fck + 1.65σ (standard deviation).

What is f_y in structural design?

Yield strength of steel (e.g., FE 250, FE 415, FE 500).

What are the partial safety factors gammac and gammas used for?

They are the partial safety factors for concrete and steel used in design strength calculations.

What is the design requirement in limit state method relating design resistance and design loads?

Design resistance Rd must exceed design loads Sd (Rd > Sd).

How is the concrete design strength adjusted to account for strength variability in code calculations?

Design strength for concrete is 0.67 fck (i.e., cylinder strength is 0.8 of cube strength; design strength is 0.85 × 0.8 × fck = 0.67 f_ck).