Reinforced Concrete Slabs - Concept Map
Reinforced Concrete Slabs: Design, Analysis, and Detailing
Related concepts
One-Way vs Two-Way Slab Classification
Sub concepts
- Span ratio criteria (long/short ≥ 2)
- Support conditions
- Load distribution patterns
- Bending behavior
Relationship to central
Foundational classification determining design approach and analysis method
Minimum Thickness (Deflection Control)
Sub concepts
- Support condition formulas (L/20, L/24, L/28, L/10)
- Yield strength adjustment factor
- NSCP 2015 provisions
- Cantilever considerations
Relationship to central
Critical requirement to prevent excessive deflection without explicit checks
Flexural Design per Metre Strip
Sub concepts
- Unit strip analysis (b = 1000 mm)
- Moment calculation (Mu)
- Moment strength (Rn = Mu/φbd²)
- Steel ratio computation (ρ)
- Required reinforcement (As)
- Bar spacing conversion (s = Ab×1000/As)
Relationship to central
Main structural design methodology for slab capacity
Shrinkage and Temperature Steel
Sub concepts
- Minimum ratio (ρtemp = 0.0018 for fy = 415–420)
- Alternative ratio for fy = 275
- Placement perpendicular to main bars
- Spacing limits (5h, 450 mm max)
Relationship to central
Essential secondary reinforcement perpendicular to main steel
Two-Way Slab Analysis Methods
Sub concepts
- Coefficient method (on stiff beams)
- Direct Design Method (DDM) on columns
- Equivalent Frame Method (EFM)
- Static moment distribution (Mo = wuL₂Ln²/8)
- Column and middle strip moments
Relationship to central
Advanced analysis for panels supporting loads in both directions
Reinforcement Detailing and Limits
Sub concepts
- Main bar spacing limits (3h, 450 mm)
- Temperature bar spacing (5h, 450 mm)
- Minimum steel ratios
- Bar size and development length
- Curtailment requirements
Relationship to central
Practical construction and crack-control requirements
Code Provisions and Standards
Sub concepts
- NSCP 2015 (National Structural Code of the Philippines)
- ACI 318 (American Concrete Institute)
- RA 544 (Philippine Building Safety Law)
- AISC 360 (relevant for composite action)
Relationship to central
Regulatory framework governing all slab design decisions
Concept connections
- One-Way vs Two-Way Slab ClassificationFlexural Design per Metre StripClassification determines whether single-direction or dual-direction analysis is performed; one-way uses strip method directly
- Minimum Thickness (Deflection Control)Flexural Design per Metre StripMinimum thickness establishes the effective depth d available for moment capacity; adequate thickness ensures structural depth for reinforcement
- Flexural Design per Metre StripShrinkage and Temperature SteelAfter main flexural steel is determined, perpendicular temperature steel is designed to prevent shrinkage cracking; minimum ratio may govern total steel
- Reinforcement Detailing and LimitsFlexural Design per Metre StripSpacing limits constrain the practical application of calculated steel areas; bar selection and spacing are derived from design area
- Reinforcement Detailing and LimitsShrinkage and Temperature SteelBoth main and temperature steel must satisfy independent spacing limits (3h vs 5h); limits ensure crack control and constructability
- Two-Way Slab Analysis MethodsFlexural Design per Metre StripTwo-way analysis methods (coefficient or DDM) produce moment distributions that are then designed using the same per-metre strip flexural methodology
- One-Way vs Two-Way Slab ClassificationTwo-Way Slab Analysis MethodsTwo-way classification triggers the need for specialized analysis methods (coefficient method, DDM, or EFM) not required for one-way slabs
- Code Provisions and StandardsMinimum Thickness (Deflection Control)NSCP 2015 and ACI 318 define the minimum thickness formulas (L/20, L/24, etc.) and adjustment factors for different yield strengths
- Code Provisions and StandardsShrinkage and Temperature SteelNSCP 2015 and ACI 318 mandate minimum ratios (0.0018 or 0.0020) and spacing limits for temperature steel
- Code Provisions and StandardsTwo-Way Slab Analysis MethodsNSCP 2015 and ACI 318 prescribe coefficient values, DDM assumptions, and static moment distribution rules for two-way slabs
- Flexural Design per Metre StripReinforcement Detailing and LimitsThe calculated steel area (As) is converted to practical bar spacing using development length, splice requirements, and spacing limits from detailing rules
- One-Way vs Two-Way Slab ClassificationReinforcement Detailing and LimitsClassification affects curtailment patterns and reinforcement continuity; one-way slabs typically have simpler curtailment than two-way panels
Diagrams
Reinforced Concrete Slabs: Complete Concept Hierarchy
Hierarchical mind map showing all major concept branches of reinforced concrete slabs design, from classification through analysis methods to detailing requirements. This serves as the comprehensive overview of the chapter content.
One-Way Slab Flexural Design Process
Step-by-step flowchart for designing the main flexural reinforcement in a one-way slab. Covers minimum thickness verification, moment strength calculation, steel ratio determination, and spacing conversion for practical construction.
Slab Classification: One-Way vs Two-Way Decision Tree
Decision tree for classifying rectangular slabs as one-way or two-way based on geometric proportions and support conditions. Each classification branch leads to the appropriate design methodology.
Shrinkage and Temperature Steel Design Process
Complete design process for shrinkage and temperature reinforcement. Shows ratio selection based on yield strength, area calculation per metre width, bar selection, spacing computation, and verification against limits.
Slab Design Analysis State Progression
State diagram showing the logical progression of slab design from initial problem definition through final detailing. Demonstrates the decision points and sequential steps in the design workflow.
Typical Load Distribution in Reinforced Concrete Slabs
Pie chart showing the typical composition of design loads in reinforced concrete slab systems, illustrating the relative proportions of dead load, superimposed dead load, and live load that engineers consider in design calculations.