Need a book?
Engineering books recommendations...
Return to index:
Re: component and cladding vs MWFRS
- To: seaint(--nospam--at)seaint.org
- Subject: Re: component and cladding vs MWFRS
- From: "Conrad Harrison" <metamorphs96(--nospam--at)gmail.com>
- Date: Wed, 31 Dec 2008 16:50:39 +1030
It is still a matter of interpretation of ASCE7, and how well the engineer is capable of justifying their case to the building officials. Part of the key in the phrase is the word "also", it also implies design to MWFRS pressures. The structure has to be assessed for the appropriate loads and under the appropriate conditions. The statement is more of a warning not to ignore the C&C pressures, and to explicitly dismiss them if not considered relevant. If use the pressure coefficients will probably notice as effective area increases the C&C pressure coefficients drop, getting closer and closer to the MWFRS pressure coefficients. The more effort put into using the code the and assessing wind loading, the lower the wind load can be dropped to keep traditionalists happy, and strength can be provided where actually needed to minimise expense.
Here cyclone Tracy demonstrated that the traditional construction of roofs held together, since entire roofs were picked up and dropped on the floor beside the house. So getting adequate tie-down is important. Understanding the tributary area of the isolated building element is important to developing economic solutions. But more cost for engineering to reduce resistance is not entirely sensible, so engineering effort is dependent on the nature of the project and the economy which can be achieved.
Just suggesting that if builders/owners give you a hard time over high expense, then worth taking a lot closer look at what is achievable, rather than simply going along with potentially over conservative views of local building officials.
Also heres an idea, the more simplistic your calculations, then the easier for the least experienced building official to review your work. The more complex your calculations, then the greater the need for the most experienced building official to review your work, to the extent the calculations have to be sent out to be reviewed by another engineer. The code and commentary permit rational design using recognised texts, papers and references. The code is just a guide, with an origin in learned opinion, make use of the papers the commentary references. The more evidence presented to support your case, the more difficult it is for building officials to find a reason to reject your proposal. And evidence is what it is all about.
PS: best wishes for the new year.