To draw a sectional plan and elevation of simply supported one-way and two-way RCC slabs.

Here’s a comprehensive practical guide for drawing sectional plans and elevations of simply supported RCC slabs:

Practical Execution Sheet

Materials Required

• Manual Drafting:
  A1/A2 drawing sheet, HB/2H pencils, eraser, scale ruler (1:50), French curve, stencil for rebars
• AutoCAD:
  Computer with AutoCAD 2020+, plotter/printer, CTB file for line weights

1. One-Way Slab (Manual Method)

Sectional Plan (Scale 1:50)

1. Draw 150mm thick slab section
2. Add 25mm clear cover lines on both faces
3. Detail reinforcement:

• Main bars: Ø12@150c/c (bottom)
• Distribution bars: Ø8@250c/c (top)

1. Show 90° hooks at bar ends
2. Hatch with ANSI31 pattern (45° lines @ 3mm spacing)

Elevation

1. Draw 4000mm span between supports
2. Indicate 230mm thick supporting walls
3. Detail:

• Slab thickness: 150mm
• Development length: 450mm beyond supports
• Support bearing: 150mm

2. Two-Way Slab (AutoCAD Method)

Step-by-Step Commands

1. _UNITS → Millimeters / Decimal degrees  
2. _LAYER → Create: SLAB, REBAR, DIMS, HATCH  
3. _RECTANGLE → 5000×4000mm (slab outline)  
4. _OFFSET → 25mm (clear cover boundary)  
5. _ARRAYRECT:  
   - X-direction bars: Ø10@150c/c  
   - Y-direction bars: Ø10@150c/c  
6. _MLEADER → "Fe415 Steel" with arrow to rebars  
7. _DIMSTYLE → Create "SLAB-DIMS":  
   - Arrow size: 2.5mm  
   - Text height: 3mm  
8. _HATCH → Concrete (ANSI31, Scale 15)  

Key Comparison Table

Critical Details to Show

1. Support Conditions:

• Simple support symbols (半圆形表示)
• Minimum bearing length: 100mm

1. Reinforcement:

• Lap length: 45Ø (for Fe415)
• Cranked bars at supports (if moment reinforcement)

1. Dimensioning:

• Overall slab dimensions
• Effective depth (d = D – cover – Ø/2)
• Center-to-center spacing of bars

Evaluation Checklist

✅ Correct scale maintenance (±2% tolerance)
✅ Clear differentiation between main/distribution bars
✅ Proper concrete hatching orientation
✅ Inclusion of all mandatory notes:

• “All dimensions in mm”
• “Clear cover 25mm maintained”
• “M25 concrete with Fe415 steel”

Common Errors to Avoid

1. Incorrect bar bending schedules
2. Missing temperature reinforcement (0.12% of cross-section)
3. Overlapping dimension arrows
4. Inconsistent line weights (use 0.5mm for slab outlines, 0.18mm for rebars)

Submission Requirements

• Manual draft: 2×A2 sheets (plan + elevation for both slab types)
• AutoCAD output: PDF (color) + DWG file
• Calculation sheet for:
• Load calculations (DL+LL)
• Moment coefficients (IS 456:2000)
• Reinforcement percentages