🏗️ Mastering Reinforced Concrete Building Design Using ETABS: A CPD Guide for Filipino Engineers

🗓️ Updated: June 2025
📍 By Engineer Cokie’s Civil Engineering Blog

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🧱 Introduction: Bridging Theory and Technology in Structural Design

In the ever-evolving field of structural engineering, mastering digital tools like ETABS (Extended Three-Dimensional Analysis of Building Systems) is no longer a bonus—it's a necessity. This article summarizes a CPD-accredited course titled "Design of Reinforced Concrete Buildings Using ETABS" by structural engineering expert Engr. JM Landingin, aiming to bridge traditional design principles with modern analysis software, all in alignment with the NSCP 2015 and ACI 318-14M.

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📘 Course Profile: From Classroom to Construction Site

👨‍🏫 Presenter: Engr. Jaime Manalili Landingin, RCE, MBA, MEng (Structural)

• Ph.D. Candidate (Aveiro, Portugal)
• CEO, Aveiro Civil Engineering Services
• Former Design Manager, Archetype Myanmar
• Former Professor, TIP QC

His research focuses on bi-axial cyclic loading in RC columns, equipping participants with insights drawn from both field and academic experience.

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🏢 What Is ETABS and Why It Matters?

• 3D modeling of RC frames
• Static & dynamic (e.g., seismic) analysis
• Code-compliant design checks (NSCP, ACI, ASCE)

Its robust tools like Pushover Analysis, Time History Analysis, and Staged Construction make it ideal for high-rise structures in earthquake-prone regions like the Philippines.

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📐 Design Workflow Using ETABS: Step-by-Step

🔹 Step 1: Define Geometry and Materials

• 4-storey RC building: Columns & beams = 300×450 mm, slab = 120 mm
• Concrete: f’c = 27.58 MPa
• Steel: fy = 415 MPa
• Live Load: 3 kN/m² | Floor Finish Load: 1 kN/m²

🔹 Step 2: Load Patterns & Combinations

• EQX, EQY seismic loads
• Wind loads (basic speed = 240 kph)
• Load combinations: D+L, D+0.7E, D+W+0.5L, etc.

🔹 Step 3: Model Setup in ETABS

• Define material and section properties
• Draw elements: beams, slabs, columns
• Assign supports, diaphragms, and restraints
• Check mass source and drift limits

🔹 Step 4: Run Analysis

• View deformed shapes
• Review shear/moment diagrams
• Compare ETABS-calculated and manual dead loads
• Check base shear, storey drift, and design compliance

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📊 RC Design Principles from the Course

📌 Slabs

• One-Way Slabs: L/S ≥ 2; reinforced along one direction
• Two-Way Slabs: L/S < 2; reinforcement in both directions
• Minimum thickness and reinforcement spacing per NSCP 2015 Sections 407–408

📌 Beams

• Flexure and shear per NSCP 2015 Section 409
• Longitudinal and shear reinforcement with code checks

📌 Columns

• Short Columns: Direct axial loads
• Slender Columns: P-Δ effects
• Reinforcement limits per NSCP 2015 Section 410

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🌐 Advanced ETABS Features Highlighted

🚧 Staged Construction

Simulates sequential building phases and considers time-dependent behaviors like creep and shrinkage.

⚡ Dynamic Analysis

• Response Spectrum Analysis
• Time History Analysis

🌀 Rigid Diaphragm Action

Improves lateral load distribution and minimizes torsion.

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📐 Sample Problem: ETABS-Based RC Beam Design (NSCP 2015 + ACI 318-14M)

🧹 Problem Statement

Beam span: 5.0 m
Cross-section: 300 mm × 450 mm (b × h)
Concrete strength: f'c = 27.58 MPa
Steel strength: fy = 415 MPa
Dead Load (DL): Self-weight + 2.0 kN/m
Live Load (LL): 3.0 kN/m
Design Code: Strength Design (LRFD)
Cover: 50 mm

📊 Step 1: Calculate Ultimate Design Load

w_u = 1.2(DL) + 1.6(LL)
Beam self-weight = 0.3 × 0.45 × 23.54 = 3.18 kN/m
DL = 3.18 + 2.0 = 5.18 kN/m
w_u = 1.2 × 5.18 + 1.6 × 3 = 11.02 kN/m

📐 Step 2: Compute Maximum Moment

M_u = w_u × L² / 8 = 11.02 × 25 / 8 = 34.44 kN·m
= 34.44 × 10⁶ N·mm

🔧 Step 3: Compute A_s

φ = 0.9
M_n = M_u / φ = 38.27 × 10⁶ N·mm
Effective depth d = 450 - 50 - 10 = 390 mm
Assume a = 90 mm
A_s = M_n / [fy(d - a/2)] = 267.3 mm²

🔪 Step 4: Select Reinforcement

12 mm bar = 113.1 mm²
Required = 267.3 / 113.1 ≈ 2.36 → Use 3-12mm bars

📏 Step 5: Minimum Steel Check

A_s_min = (3√f'c / fy) × b × d ≈ 266 mm²
→ A_s = 339.3 mm² > A_s_min = OK

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✅ Final Beam Design Summary

Parameter	Value
Beam Size	300 mm × 450 mm
Factored Load	11.02 kN/m
Ultimate Moment	34.44 kN·m
Required As	267.3 mm²
Provided Steel	3-12 mm bars (339.3 mm²)
Code Compliance	NSCP 2015 Section 409

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📣 Engineer’s Tip

• Assign correct material & section properties
• Use valid load combinations (NSCP)
• Run ETABS analysis & compare with manual results
• Check deflections, drift, reinforcement adequacy

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💬 Comment your ETABS tips and questions!

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