Until now, CHECKWIND has used a combination of the 500 m segment criteria from the AS/NZS 1170.2 commentary (though with a “rolling” 500 m segment instead of less accurate 500 m increments from the crest suggested by AS/NZS 1170.2), in addition to our own local minimum criteria to determine the base of a feature.
Figure 1: AS/NZS 1170.2 C4.4.2
However, the problem with utilising the local minimum criteria is that the base might be determined as being at the bottom of a valley with a steep slope for certain terrain, leading to overly conservative Mt values, as shown in Figure 2.
Figure 2: CHECKWIND v2.2.1 results
The local minimum criteria was intended to avoid situations where the 500 m segment might identify the “base” as being halfway up/down a slope, which seemed counter intuitive. Regardless, we’ve adjusted the algorithm and removed the local minimum criteria and now rely solely on the 500 m segment method. This has led to an overall reduction in Mt values across all of our test sites, as shown in Figure 3.
Since opening the CHECKWIND beta in August of last year, over 500 users have supported us by downloading, sharing and providing feedback. It’s taken longer than we hoped to get to this point, but we think you’ll agree it was worth the wait. We listened to your feedback and have rewritten and improved nearly every aspect of the program, which is available to download here.
All users who participated in the beta will be supplied with a free 3 month licence active from today as a sign of our gratitude, and will receive instructions on activation in a separate email.
A simple interface which streamlines inputs for non-technical users.
An advanced interface for experienced users to tweak every parameter.
AS/NZS 1170: Automatic Wind Region and Lee Zone determination based on NIWA maps.
AS/NZS 1170: Automatic shielding structure detection for the Shielding Multiplier (Ms).
Generate site-specific PDF reports with satellite image overlays.
It’s not uncommon to hear engineers say “we assume everything is 1.0 because that’s conservative”. Until now, it’s been too hard to utilise terrain category averaging or shielding. With CHECKWIND, you can safely and transparently reduce your wind pressures by more than 50% compared with the more “traditional” approach by just identifying your site on the map.
As of today, the CHECKWIND beta is open to the public. It’s focused on our groundbreaking Google Maps integration for 1-click wind analysis, featuring an automated Topographic Multiplier (Mt) calculator, terrain category averaging, definition of shielding buildings using satellite imagery, wind region detection, and lee zone detection and calculation for New Zealand.
The beta is completely free and can be shared with anyone you like. We’re looking to test it on a broad range of systems to stamp out the trickier bugs bugs that only appear under particular hardware/network/Windows configurations outside of our available testing environment. We appreciate your patience as the application evolves over the next few weeks/months, and let us know if you encounter something that isn’t right.