LECTURE 2 - Advance Construction Methods and Beams

Set

The assumption of a rigid or hard state by concrete, mortar, plaster, or glue due to a physical or chemical change.

Cure

Maintaining newly placed concrete at required temperature and humidity for the first seven days to ensure proper hydration and hardening.

Heat

generated during the chemical reaction (hydration) when cement mixes with water.

Hydration

The chemical process where cement combines with water, leading to concrete hardening.

Beam

A rigid structural member designed to carry transverse loads, subject to bending and deflection.

Deflection

The perpendicular distance a spanning member deviates under load, influenced by load, span, and material properties.

Bending Moment

An external moment causing rotation or bending in a structure, calculated as the sum of moments about the neutral axis.

Resisting Moment

An internal moment equal and opposite to the bending moment, maintaining equilibrium.

Neutral Axis

An imaginary line through the centroid of a beam’s cross-section where no bending stresses occur

Top Bars

Longitudinal bars in a concrete beam’s upper section to resist negative bending moments (tension zone).

Stirrups

U-shaped or closed-loop bars perpendicular to longitudinal reinforcement, resisting diagonal tension in beams.

Bent Bars

Longitudinal bars bent at ≥30° to intersect diagonal tension cracks in beams.

Bottom Bars

Longitudinal bars in a beam’s lower section to resist positive bending moments (tension zone).

Truss Bars

Longitudinal bars bent up/down at points of moment reversal in beams.

Flexural Cracks

Cracks due to bending stresses, appearing perpendicular to the beam’s span.

Shear Cracks

Diagonal cracks near supports caused by shear stresses exceeding concrete’s tensile strength.

Top Bars

where are more reinforcement bars installed in a cantilever beam?

Lift-Slab Construction

Casting horizontal slabs at ground level and lifting them into place with hydraulic jacks for multistory buildings.

Slip Form

A movable formwork system used continuously during concrete placement, e.g., in pavements or vertical structures.

Climbing Form

Formwork raised vertically for successive concrete lifts in multistory construction.

Flying Form

Large crane-movable formwork sections used for constructing floors/roofs in multistory buildings.

Grade 40

40,000 psi tensile strength

Grade 60

60,000 psi tensile strength

Eero Saarinen

Designed the TWA Terminal

Web Reinforcement

Includes stirrups and bent bars to resist diagonal tension in beams.

Lift

The height of concrete placed in a form at one time.