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
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
6.8 CALCULATION OF DEFLECTION OF BEAMS AND SLABS FOR SERVICEABILITY LIMIT STATE
6.8.1 General
6.8.3 Calculation of deflection by empirical model
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
7.4.2.8 Balanced conditions
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
7.5.8 Design yield strength of shear reinforcement
7.5.10 Minimum area of shear reinforcement
SECTION 8 STRESS DEVELOPMENT, DETAILING AND SPLICING OF REINFORCEMENT AND TENDONS
8.8 SHRINKAGE AND TEMPERATURE REINFORCEMENT
8.8.1 Floor and roof slab reinforcement (two-way slab strips)
SECTION 9 DESIGN OF REINFORCED CONCRETE BEAMS AND ONE-WAY SLABS
9.3 GENERAL PRINCIPLES AND DESIGN REQUIREMENTS FOR BEAMS AND ONE-WAY SLABS
9.3.1 General
9.3.1.2 Effective width resisting compression of T-beams and L-beams
9.3.1.4 Contribution of slab reinforcement to design strength of T and L-beams
9.3.8 Longitudinal reinforcement in beams and one-way slabs
9.3.8.1 Maximum longitudinal reinforcement in beams and one-way slabs
9.3.8.2.4 Minimum reinforcement in slabs and footings
9.3.8.3 Spacing of reinforcement in slabs
9.3.9 Transverse reinforcement in beams and one-way slabs
9.3.9.2 Diameter and yield strength of transverse reinforcement
9.3.9.3 Design for shear
9.3.9.4.12 Spacing limits for shear reinforcement
9.3.9.4.15 Minimum nominal shear strength provided by shear reinforcement
SECTION 12 DESIGN OF REINFORCED CONCRETE TWO-WAY SLABS
12.5 DESIGN FOR FLEXURE
12.5.6 Slab reinforcement
12.5.6.2 Area of reinforcement
12.5.6.3 Spacing of flexural reinforcement
12.6 SERVICEABILITY OF SLABS
Assumptions
This module performs gravity (ultimate and serviceability) design of reinforced concrete slab strips to NZS 3101:Part 1:2006 incorporating Amendments 1, 2 and 3. The serviceability and deflection checks do not affect the reinforcement design, however they will generate warnings or error messages if they are not satisfied.
Clause 2.4.2 / 6.8 - deflection is checked against a user-specified span/deflection ratio limit and an absolute (gross) deflection limit, for both short-term (serviceability) and long-term (sustained/total) deflections. Exceedance of either limit raises a warning only.
Clause 5.2.3 - the elastic modulus used for the slab is the Eq 5-1 value, not the material-library value. A separate advisory warning is raised when the supplied (library) Ec differs from the Eq 5-1 value by more than 5%; the warning does not change the design value.
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 7.4 - Flexural strength is computed by a solver that meshes the cross section and calculates capacity using strain-compatibility and the stress-strain curve of the materials. The equivalent rectangular stress block of Clause 7.4.2.7 is used as the stress-strain curve of the concrete.
Clause 7.5.4 - ka is assumed to be 0.85.
Clause 9.3.1.2 - For flanged strips (T- and L-shaped) the flexural capacity checks use an effective section in which each flange outstand is clipped to the smaller of the span/8, eight times the flange thickness
Clause 9.3.1.3 - For flanged strips (T- and L-shaped) the deflection checks use an effective section in which each flange outstand is clipped to be half of the smaller of span/8 and eight times the flange thickness
Clause 9.3.9.3 - The effective shear area Acv is the web width times the effective depth (bw·d) for rectangular, T- and L-shaped strips per Cl. 9.3.9.3.3(a).
Torsional capacity, punching shear, 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.