A Beginner's Guide to ASCE 7-05

Chapter 6 - F_a: Flood Loads

© 2007, T. Bartlett Quimby

Section 6.8

Homework Problems

Last Revised: 11/04/2014

Problem M6.1:  In Figure 6.8.1 below, a series of 18" diameter steel piles are exposed to ocean storm flooding and waves.  Anticipate that, in a storm event, there will be an additional 12 inches of erosion.  Be conservative in estimating the water velocity.

• Problem M6.1a:  Compute the force due to a breaking wave on a single pile.  At what elevation (relative to the DFE) should this force be placed for maximum structural effect(s)?
• Problem M6.1a:  Compute the force due to impact of a 1,000 lb object.  Clearly discuss your choice of variables.

Figure 6.8.1
Piles Exposed to Ocean Waves

Problem M6.2:  Let us suppose that the owners of the structures shown in Figure 6.8.1 want to explore the possibility of building a retaining wall type barrier between the structures and the ocean.  They want the wall to have 2 ft of free board above the BFE.    The wall is also to have small openings to allow water behind the wall during a storm event and to drain after the event is over.  Draw a profile of the wall face (it is a vertical face) with the pressure distribution due to breaking waves shown on it.  What is the net force per foot of wall length is to be applied for design?  Clearly discuss your choice of variables.

House Design Problem

Problem H6.1:  The lot the house sit on boards a small stream.  In real life there is no flood hazard as the stream is at least 15 ft of elevation below the house.   However, let us presume that it does flood with the still water elevation being 2 ft above current ground level.  Assuming 6 inches of erosion and the water flowing from the east, estimate the total lateral flood force exerted on the house if the space inside the house remains dry.  Be conservative on the water velocity estimate.  It is not expected that there will be any breaking waves nor do we need to worry about debris impact.