Sections considered
NZS3101:2006 Concrete Structures Standard (incorporating Amendments 1, 2 and 3)
SECTION 1 GENERAL
1.1 SCOPE
1.1.1 Relationship to NZ Building Code
1.1.3 Materials and workmanship requirements
SECTION 2 DESIGN PROCEDURES, LOADS AND ACTIONS
2.3 DESIGN FOR STRENGTH AND STABILITY AT THE ULTIMATE LIMIT STATE
2.3.2 Design for strength
2.3.2.2 Strength reduction factors, ultimate limit state (c),(e)
2.4 DESIGN FOR SERVICEABILITY
2.4.2 Deflection of beams and slabs
2.4.4 Crack control
2.4.4.4 Spacing of reinforcement for crack control on the extreme tension face
SECTION 5 DESIGN PROPERTIES OF MATERIALS
5.2 PROPERTIES OF CONCRETE
5.2.1 Specified compressive strength
5.2.2 Applicable density range
5.2.3 Modulus of elasticity
5.2.4 Direct tensile strength concrete
5.2.5 Modulus of rupture for calculation of deflections
5.3 PROPERTIES OF REINFORCEMENT
5.3.2 Reinforcement grades
5.3.2.3 Ductility class
5.3.3 Strength
SECTION 6 METHODS OF STRUCTURAL ANALYSIS
6.3 LINEAR ELASTIC ANALYSIS
6.3.7 Moment redistribution in reinforced concrete for ultimate limit state
6.8 CALCULATION OF DEFLECTION OF BEAMS AND SLABS FOR SERVICEABILITY LIMIT STATE
6.8.1 General
6.8.3 Calculation of deflection by empirical model
(a),(b)
SECTION 7 FLEXURE, SHEAR, TORSION AND ELONGATION OF MEMBERS
7.4 FLEXURAL STRENGTH OF MEMBERS WITH SHEAR AND WITH OR WITHOUT AXIAL LOAD
7.4.1 Flexural strength requirement
7.4.2.3 Maximum concrete strain
7.4.2.7 Equivalent rectangular concrete stress distribution
7.5 SHEAR STRENGTH OF MEMBERS
7.5.1 General
7.5.2 Maximum nominal shear stress, vmax
7.5.3 Nominal shear strength, Vn
7.5.4 Nominal shear strength provided by the concrete, Vc
7.5.5 Nominal shear strength provided by the shear reinforcement, Vs
7.5.8 Design yield strength of shear reinforcement
7.6 TORSIONAL STRENGTH OF MEMBERS WITH FLEXURE AND SHEAR WITH AND WITHOUT AXIAL LOADS
7.6.1 Members loaded in torsion
7.6.1.2 Threshold torsional reinforcement
7.6.1.3 Requirement for torsional reinforcement
7.6.1.4 Torsion due to deformation compatibility
7.6.1.6 Torsional strength requirements
7.6.1.7 Torsional shear stress
7.6.1.9 Torsional and flexural shear together
7.6.2 Reinforcement for compatibility torsion
7.6.2.1 Minimum reinforcement for compatibility torsion
7.6.3 Torsional reinforcement details
7.6.3.2 Maximum stirrup spacing
7.6.4 Design of reinforcement for torsion required for equilibrium
7.6.4.1 Design moment for torsion
7.6.4.2 Areas of closed stirrups and longitudinal reinforcement
SECTION 8 STRESS DEVELOPMENT, DETAILING AND SPLICING OF REINFORCEMENT AND TENDONS
8.6 DEVELOPMENT OF REINFORCEMENT
8.6.3 Development length of deformed bars and deformed wire in tension
8.6.3.1 Development length in tension
8.6.3.2 Basic development length in tension
SECTION 9 DESIGN OF REINFORCED CONCRETE BEAMS AND ONE-WAY SLABS FOR STRENGTH, SERVICEABILITY AND DUCTILITY
9.3 GENERAL PRINCIPLES AND DESIGN REQUIREMENTS FOR BEAMS AND ONE-WAY SLABS
9.3.1.2 Effective width resisting compression of T-beams and L-beams
(a),(b),(c)
9.3.8 Longitudinal reinforcement in beams and one-way slabs
9.3.8.1 Maximum longitudinal reinforcement in beams and one-way slabs
9.3.8.2.1 Minimum reinforcement in beams
9.3.9 Transverse reinforcement in beams and one-way slabs
9.3.9.2 Diameter and yield strength of transverse reinforcement
9.3.9.4.12 Spacing limits for shear reinforcement
9.3.9.4.13 Minimum area of shear reinforcement
9.3.9.4.15 Minimum nominal shear strength provided by shear reinforcement
Assumptions
This module designs reinforced (non-prestressed) concrete beams to NZS 3101:Part 1:2006 incorporating Amendments 1, 2 and 3, for gravity (non-seismic) load combinations. Member design actions (service, sustained and ultimate moments) are taken from the SPACE GASS 3D frame analysis.
Clause 5.2.3 - The elastic modulus Ec adopted for the beam is the value carried in the material library, not Eq. 5-1. An advisory warning is raised when the library Ec differs from the Eq. 5-1 value Ec = 4700 (density/2300)^1.5*sqrt(f'c) by more than 5%; the design value is not changed by this warning.
The serviceability reinforcement service stress fs is obtained from a cracked transformed section (modular ratio n = Es/Ec) under the short-term service moment Ms, capped at fsy.
Clause 6.8.3 - Per-span Ie is a Branson-weighted average. For a cantilever, Ie is calculated at the support only. For a simply supported span, Ie is calculated at midspan. For spans where one end is continuous, Ie is 0.85 * Ie at midspan + 0.15 * Ie at continuous support. For spans where both ends are continuous, Ie is 0.15 * Ie at left continuous support + 0.70 * Ie at midspan + 0.15 * Ie at right continuous support. These weights follow the Branson convention referrenced by the NZS C6.8.3(a) commentary.
Clause 6.8.3(b) - Additional long-term deflection = Ks*Kcp*(short-term deflection). Ks is computed per span as max|M_sustained| / max|M_service|. Kcp (creep/shrinkage factor, Eq. 6-4) is evaluated at the span midpoint from the compression-reinforcement ratio p'.
Clause 7.4.2.7 - Flexural strength uses the equivalent rectangular stress block with an extreme-fibre concrete strain of 0.003 (Clause 7.4.2.3). φMn is computed by strain-compatibility section integration with α1 and β1 as defined in Clause 7.4.2.7.
Clause 7.5.4 - ka is assumed to be 0.85.
When ligatures are provided, the outer ligature is assumed to be closed.
Earthquake (seismic) provisions, prestressed concrete and fire resistance are not considered by this module. Serviceability outputs (crack control to Clause 2.4.4 and deflection to Clause 6.8) are reported as advisory warnings and do not control the reinforcement design.