World Trade Center 7 NIST Collapse Simulation
Lu-Jiang Model of the Collapse of WTC 1 and WTC 2
Computer Simulation Examples
World Trade Center Simulations
World Trade Center Blueprints
[0609105 Cherry Tree vs. Crˆepes Suzette: Global Model of Collapse of the World Trade Centers]
Do NIST's computer models meet the International Building Codes?
Topic started on 3-11-2008 @ 02:10 PM by Griff
Let's look at the criteria for the "International Code Council Performance Code For Buildings and Facilities" to find out.
USE OF COMPUTER MODELS
This appendix gives guidance regarding qualifications and information that should be provided when undertaking computer modeling. More specifically, the appendix requests that computer program data be submitted as part of the documentation. Also, limitations and applicability of the model must be included as part of the documentation. Finally, the scenarios used to run the particular model must be justified. This is an area along with the analysis of individual performance-based designs and methods where organizations such as evaluation services may have a role. The model is only as good as the input selected and the specific application of the model. Very often, inappropriate and unrealistic input data is used, and models often have very specific application limitations. Therefore, simply because a model has been reviewed does not mean that enough information has been provided for the specific application to be accepted. The criteria used to approve the model must be very specific in order to provide guidance to the code official or outside reviewer as to what specifically about the model has been reviewed. These criteria will provide a clear understanding of what additional review of that specific application of the model may be necessary.
Personally, I feel NIST has failed.
Edit: Sorry for not supplying a link. You have to pay for the IBCs and it would probably be considered pirating if I supplied a link to them (if there even is one). I bought my copy, that is why I can copy and paste it.
1. Collapse Models
NIST's computer-generated models of the collapse of WTC 7, as in Figure 12-69 of NCSTAR 1-9 and Figure E-4 of NCSTAR 1-9A, as well as the collapse models presented at http://www.nist.gov/public_affairs/r...tc_videos.html do not correspond with the way in which the building can be seen descending on the several videos that captured the collapse. In the videos, the perimeter walls, connected to and supported by the large number of perimeter columns, retain their rectangular shape until late in the collapse; the perimeter columns clearly do not almost immediately buckle inwards over the building as they do in NIST's models. Therefore, NIST needs to develop a collapse model that describes the way in which WTC 7 actually collapsed on September 11th. -Vesa