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Re: ASCE 7-05 Cantilevered Column System vs. Inverted Pendulum-Type Structures

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Thanks Harold
I saw those sections after my fingers were more relaxed. So now the grade beams will be designed for omega x the actual moment and the base plates for 1.5 x actual moment.
The 155 for axial stress is hardly ever a problem since deflection is usually the governing factor.
In a message dated 3/11/2008 1:09:04 PM Pacific Standard Time, spraguehope(--nospam--at) writes:
The intent of the nonbuilding structures section was to stand alone.  We have many systems that are not allowed of they were categorized as buildings, but are a reality in the nonbuilding structure world.  We just take the hits from low R values and height limits and carry on. 
The buildings people don't look at it quite that way.  I would suggest reading the ASCE 7 Sections and  The NEHRP commentary does shed some light that occurred in the development process. 
The thought process was that with an R factor approaching a linear response, we could back off a bit on the overstrength factor.  Just stay lower than 35 ft tall "building" structures.  That would kill a lot of "nonbuilding structures" that are designed as cantilever columns. 
Harold Sprague

From: Jnapd(--nospam--at)
Date: Tue, 11 Mar 2008 15:58:41 -0400
Subject: Re: ASCE 7-05 Cantilevered Column System vs. Inverted Pendulum-Type Structures
To: seaint(--nospam--at)

I use line G.  1. in table 12.2-1 and design base plate as moment connection.
The ASCE committee people must not design buildings with patio areas or widow walls in a smaller scale than the main building, and especially not residential.
The Inverted Pendulum column is present in most residential where there is a view in one if not several directions even to your own yard.
The Inverted Pendulum column as indicated in table 15.4-2 should be in table 12.2-1.
If the intent was there the English is terrible. If in Section G of table 12.2-1 the intent of items 1-7 is to describe the type of connection at the joints, which is the way we interrupt it to be, it could have been worded such that engineers do not have to figure out what the real intent is. 
If you read 2003 NEHRP Commentary section it suggest you design the base connection for 1.5 x actual moment and .5 x actual moment at top.
Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA