Monday 15 June 2020

How is ASCE 7 Organized for Seismic Engineering

Besides signing up for this course, obtaining a copy of and getting comfortable with the latest version of ASCE 7 is the best thing you can do for yourself to prepare for the California Seismic P.E. exam. 

This test is fast paced, so the last thing you want to spend time doing is flipping through the code to find the information you need. 

Here's a quick overview of some important sections to get you started: 

Chapter 11 

Chapter 11 is used on the exam to determine the ground acceleration parameters, site class, and seismic design category. Section 11.4 includes formulas and tables to determine the site class, and Section 11.6 contains tables to determine the Seismic Design Category. As we discuss in the course, Seismic Design Category influences so much in a building's design including, but not limited to, permitted lateral systems, maximum building heights, lateral analysis procedures, restrictions on irregularities, and seismic detailing requirements. 

Chapter 12 

Chapter 12 contains the seismic design requirements for building structures, so for most of the exam, you'll be using this chapter. This blog post is by no means comprehensive, but I'll highlight a few of the important features. 

In my opinion, one of the most important tables in the whole code is Table 12.2-1. This should always be your starting point on the exam. It outlines each type of lateral force-resisting system, its corresponding seismic parameters for ductility, overstrength, and deflection amplification, and provides guidance on the applicability or appropriate building height limit in each seismic design category. This table is useful as a personal teaching tool or point of reference and is also a great place to start on any exam question. 

Table 12-3.1 describes each of the horizontal and vertical irregularities that are considered by the code. A building with any of these irregularities will require additional analysis or the consideration of additional seismic load, so it's important to review these definitions and commit them to memory. 

Section 12.8 outlines all the parameters needed for the Equivalent Lateral Force Procedure, from the seismic response coefficient, to base shear, to period, and deflection. If the building is permitted to be analyzed by this procedure (and for the purpose of the test, 99% of structures will be) this is where all your calculations should begin. 

Section 12.12 contains limits for allowable story drift. This is an easy place to pick up some points. Table 12.12-1 includes limits based on type of structure and risk category, but if you have a moment frame structure in Seismic Design Category D through F, be sure to consider section 12.12.1.1. 

The final section in Chapter 12 worth including here is Section 12.14-the "simplified alternative structural design criteria." There are many factors that will determine if you can use this section, and typically as far as the test is concerned, they will ask you to use this section if required. It's a simple way to determine the base shear, etc. for a building if it meets all the qualifications. 

Chapter 13 

Finally, Chapter 13, or more specifically, Tables 13.5-1 and 13.6-1 provide the ap, Rp, and Ωo values for nonstructural components. These will be used to determine their anchorage forces. 

As I said, this is in no means a full guide to ASCE 7, but if you are able to tab/bookmark/highlight these sections and get familiar with them, you'll save a lot of time on the test and, let's face it, we could all use some more time for this exam.
About the Author: Erin E. Kelly

Ms. Kelly is an experienced structural engineer with a focus on seismic risk. She has extensive experience in structural failure investigations, seismic structural design, and seismic risk assessments. Through the School of P.E., she has taught a 32-hour course for the California Seismic P.E. Exam, authored several blog posts, and contributed to other review products. She has a Bachelor of Science in Civil Engineering from Johns Hopkins University and a Masters of Engineering in Structural Engineering from Lehigh University.

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