Seismic Analysis & Earthquake Engineering - Fundamentals

Trace seismic codes progression from Building Seismic Safety Committee to FEMA and ASCE, showing ASCII and ABC provide loading criteria while design criteria reside in codes, on a five-year cycle.

Explain seismic design philosophy by allowing plastic strength beyond yield, using non-linear behavior, and ensuring no collapse while tolerating controlled structural damage during earthquakes.

Explore how seismic forces originate from slipping layers, propagate as body and surface waves, and transfer motion via soil–foundation friction; link inertia force to Newton's first law and building response.

The lecture demonstrates how seismic forces arise from Newton's laws, with inertia opposing ground motion as the foundation moves and the building's upper and lower parts respond.

Explain how earthquake shaking transfers to buildings and how they resist it with a seismic shear force. Calculate the base shear from mass times acceleration, with site and stiffness factors.

Tall and short buildings respond differently to earthquakes: mass and stiffness govern ground-acceleration transfer; short stiff structures move near acceleration, while tall flexible buildings exhibit lower accelerations but higher forces.

Trace the history of seismic design codes from early 1926 editions through ATC 3.0 and the UBC adoption, highlighting west coast hazard and European program influences.

Explain the time period as the time to complete one cycle of motion, from rest to right, then left, and back, using T = 2 sqrt(m/k) for mass and stiffness.

Explore Ss and S1, the short- and long-period spectral response accelerations, and how maps based on west coast soil guide earthquake design using MCE concepts.

Modify base acceleration maps for site B (rock) using location-specific soil coefficients. Design with a 475-year return period per California engineers, yielding about 10 percent accident probability in 50 years.

Learn the equivalent static load procedure for seismic design, including weight, importance factor, and ductility-based modification. See how nonlinear behavior and code factors adjust seismic forces.

Apply the response spectrum method to seismic analysis and derive region-based spectral components. Identify region one’s short-period constant spectral acceleration, region two’s constant spectral velocity, and region three’s constant displacement.

Learn how to develop the response spectrum curve by applying a chosen earthquake to multiple single-degree-of-freedom systems, plotting displacement, velocity, and acceleration, and extracting their maximum responses across fundamental periods.

Combine displacement, velocity, and acceleration into a single response spectrum curve to deduce all three spectra from any one, and relate short-period acceleration sensitivity, long-period displacement sensitivity, and mid-range velocity.

Explore how engineers fit the response spectrum into a three-part curve, with a straight first part for short periods, a velocity-controlled middle, and a displacement-sensitive top, to simplify seismic design.

Compare the response spectrum method with time history analysis, explaining why real earthquake behavior requires time history plots of acceleration, displacement, and the structure's response during an actual event.

Compare time history and the design spectrum, ensuring plotted accelerations align with code-based maximums; select time histories that maximize structural response for each fundamental period.

Explore time history scaling to adapt seismic records for a structure's response spectrum, adjusting acceleration and time steps to fit the code-based curve within the fundamental period range.

Examine the time history scaling method using real time histories and real earthquakes to align responses to the response spectrum, then note its disadvantages: time consuming and varied results.

Apply the seismic design philosophy to calculate forces in linear and nonlinear regimes, explain how earthquake waves transfer from ground to structure, and outline time period and code criteria.