Earthquake-Resistant Design Principles in ideCAD

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Ismail Hakki Besler

Administrator

Earthquake-Resistant Design Principles in ideCAD​

(Integrating Architectural and Structural Decisions)
This article explains how to apply core earthquake-resistant design principles step by step within the ideCAD environment.



1) Purpose and Scope: “Keep It Simple, Apply It Right”​

Earthquake safety starts with architectural design decisions that align with the structural system.
Quick wins in ideCAD:
  • Project Wizard + Code Selection: TBDY 2018, ASCE 7, Eurocode, etc.
  • Diaphragm Definition: Rigid/semi-rigid diaphragms, story mass, and center of mass definitions
  • Spectrum and Soil Data: Hazard level, local soil class, adequate ground acceleration


2) Architectural Design Sensitivities: Plan Regularity is Everything​

Flaws in the plan layout directly affect seismic performance.
In ideCAD:
  • Plan Regularity Check: Identify A1–A3 and B1–B3 irregularities and review torsion/displacement diagrams in the analysis model.
  • Shear Wall Strategy: Place walls near the mass center to support symmetry.
  • Span and Grid Continuity: Organize main spans, detect load path interruptions with clash checks.


3) Structural Sensitivities: Soft/Weak Story, Short Column, Building Separation​


In ideCAD:
  • Story-Based Stiffness/Strength Charts: Track soft/weak story warnings in design result reports.
  • Short Column Risks: Model infill/parapet effects and automate stirrup densification in detail drawings.
  • Separation Distance: Verify minimum seismic joint width in plan/section views.


4) Horizontal Systems: Diaphragms and Slabs​


In ideCAD:
  • Diaphragm Assignment: Define single or segmented diaphragms per story.
  • Composite and Steel Decks: Review shear stud, trapezoidal deck, and shell/beam interaction reports.
  • Openings in Spans: Use edge beams/shear walls to reinforce diaphragm continuity around voids.


5) Foundations and Soil: Proper Transfer, Correct Behavior​


In ideCAD:
  • Mat, Strip, Pad Foundations: Assign soil spring coefficients and review soil pressure distribution.
  • Liquefaction/Settlement: Run time-history scenarios if required.
  • Retaining Structures: Consider active-passive soil pressures and seismic surcharge.


6) Vertical Systems: Shear Walls, Frames, Braces​


In ideCAD:
  • Shear Wall–Frame Collaboration: Adjust wall ratio and distribution to keep story drift within target limits.
  • Steel Systems: Combine moment and braced frames, verify connections, and perform capacity design checks.
  • Reinforced Concrete: Ensure shear capacity, confinement, and ductility detailing; automatically reflect in drawings.


7) Nonstructural Elements: Facades and Interiors​


In ideCAD:
  • BIM Objects & Clash Detection: Check for facade anchoring and interior element placement clashes.
  • Mass Contribution: Include heavy equipment weight effects in story mass definitions.


The Ideal Workflow: 6-Step ideCAD Checklist​


  1. Code, soil, and spectrum setup
  2. Plan regularity and torsion check
  3. Diaphragm and horizontal system modeling
  4. Vertical system optimization
  5. Foundation and soil-structure interaction
  6. Nonstructural element and clash detection + report/detail generation


3 Frequently Asked Questions​


Is an asymmetrical plan always unsafe?
No. It can be safe with the right shear wall strategy and mass–stiffness balancing. Validate with drift/torsion targets in ideCAD.


What’s the first step when a soft story is flagged?
Increase story stiffness, model infill effects correctly, and bring drift ratios into the target range.


Why are horizontal systems so critical?
Without diaphragms, loads are distributed unevenly; continuity and proper assignment are key to performance.
 
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