5-Story Building Dynamic Analysis (MATLAB)

This MATLAB project was completed in 2016 as a coursework exercise for the Structural Dynamics class.
It performs a complete modal analysis of a 5-story shear building and evaluates its dynamic response under various loading conditions.

Building Parameters

• Lumped floor mass: 135 kips
• Story stiffness: 315 kips/in
• Target modal damping ratio: 0.03
• Floor heights: [12, 24, 36, 48, 60] ft
• Uniform mass and stiffness distribution across all floors

Analysis Performed

1. Modal Analysis

   • Computation of natural frequencies, periods, and mode shapes
   • Mode shapes plotted for each story under unit amplitude

2. Step Force Response

   • Modal response under a step load applied to floors
   • Time history of roof displacement and story drifts
   • Base shear and overturning moment time histories
   • Maximum displacements, drifts, base shear, and overturning moments
   • Graphical visualization of all responses

3. Harmonic Force Response

   • Modal response under a sinusoidal force (unit amplitude, first mode frequency)
   • Time history of roof displacement and story drifts
   • Base shear and overturning moment time histories
   • Maximum displacements, drifts, base shear, and overturning moments
   • Graphical visualization of all responses

4. El-Centro Earthquake Response

   • Modal response under scaled El-Centro ground acceleration (0.65g)
   • Time history of roof displacement and story drifts
   • Base shear and overturning moment time histories
   • Maximum displacements, drifts, base shear, and overturning moments
   • Both modal superposition and influence/reconstruction methods used
   • Graphical visualization of results

5. Response Spectrum / Envelope Analysis

   • Peak responses calculated using modal combination of maximum modal displacements and accelerations
   • Maximum story displacements and drifts
   • Base shear and overturning moment envelopes
   • Graphical visualization

6. Additional Calculations

   • Modal effective masses and heights
   • Participation factors for each mode
   • Comparison of maximum floor displacements under El-Centro and envelope methods

Files

• 5DOF_SDA.m — Main MATLAB script implementing all calculations
• elcentro.txt — El-Centro earthquake acceleration record used in the analysis

Course Information

• Course: Structural Dynamics
• Professor: Omid Bahar
• Student: Amir Yarmohamadi
• Year: 2016