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Rethinking Ways to Encourage Permanent Truss Bracing

Rethinking Ways to Encourage Permanent Truss Bracing Part I
Today’s article is authored by my post frame construction structural mentor.

I will mention here, Hansen Pole Buildings takes both temporary and permanent truss bracing quite seriously. Every building we provide includes an engineered permanent truss bracing plan and our Construction Manual has an entire chapter devoted to truss bracing.

By Dr. Frank Woeste, P.E.

For Component Manufacturers (CMs), it is generally well known that the Registered Design Professional (RDP) is responsible per ANSI/TPI 1 for the design of the permanent bracing system for the wood truss system. However, the issue of responsibility is only the first part of the actual design and installation of a permanent bracing system required to meet the design assumptions given on the individual truss design drawing. The purpose of this article is to suggest the use of the 2015 BCSI Book[1] (111 pages) as a tool for providing a practical path for RDPs to complete their bracing design responsibilities. If you haven’t carefully reviewed pages 37–52 on permanent bracing design, you will find 16 tightly-packed pages of details and prescriptive design information for permanent truss bracing.

Reasons to Rethink Permanent Bracing Education

Truss bracing has been on my mind since 1972 when I met the late Professor Stan Suddarth at Purdue University. At Purdue, I learned about the importance of both temporary and permanent bracing along with the engineering side of bracing design such as the 2% rule. Starting in 1978, I religiously taught Virginia Tech engineering students about the need for truss bracing and the industry literature that was available at the time.

For the past 30 years, we have been developing and offering continuing education for RDPs, truss manufacturers and designers, suppliers, and the building code community. The majority of participants have been RDPs. When covering the subject of permanent truss bracing, we were surprised to learn (early on) that a very small percentage of the group was familiar with the historic 2% rule used to design truss bracing. Additionally, few attendees had knowledge of the truss design standard content (now ANSI/TPI 1) and associated bracing documents referenced in our building codes. Naturally, we continued to cover truss bracing theory and demonstrate bracing design calculations in our courses with the goal of impacting permanent-bracing-design practice nationwide.

Fast forwarding to our 2015 VT short course, I decided to “pass around” a copy of the BCSI Book as a supplement to my traditional lecture on permanent truss bracing design. About a month later, a Building Official (BO) contacted me and shared the fact that two of his Building Inspectors who attended the course had made notes as to the scope and content of the BCSI Book. After learning that the BCSI Book was available from the SBCA, he immediately purchased copies for his inspection staff to keep in their vehicles for their framing inspection work.

In our 2016 short course, I adopted the BCSI Book as a textbook for the two-day program. At the beginning of the permanent bracing unit, I asked the group of 56 engineers and code folks if they had ever seen the book. A couple of truss folks raised their hands. We then spent about 30 minutes on bracing calculations and about 60 minutes on pp. 37–52 of the BCSI Book. The 2015–16 experiences caused me to rethink the implementation of permanent truss bracing at the field level and begin focusing on a “hybrid prescriptive approach” verses the “engineering analysis” design approach.

How the Component Manufacturer (CM) Can Help

In presentations on truss bracing, some RDPs have commented that they rarely see the Truss Design Drawings for a project, while others review them but do not prepare a permanent bracing plan. Because of the natural or required interaction between a CM and GC in securing trusses for a project, I believe the CM is in the best position to provide education for their customers on the content of the BCSI Book and how conveniently the book can be used by all parties involved in wood truss construction. A path to the RDP may be though your customer, typically the GC, for the project. An indirect way to educate the RDP on the subject of permanent truss bracing may be to share your knowledge or bracing resources with your customer.

Some points to consider covering with the GC are:

The 2015 IBC referenced standard for wood trusses is ANSI/TPI 1[2]. This document requires the Contractor to have the “Truss Submittal Package” reviewed by the Building Designer prior to installing the trusses. From ANSI/TPI 1–2014 (a free download):

2.3.4.3 Truss Submittal Package Review.
The Contractor shall not proceed with the Truss installation until the Truss Submittal Package has been reviewed by the Building Designer.
Assuming that the RDP does not provide permanent bracing guidelines for a truss package after they have reviewed and returned the Truss Design Drawings (TDDs), the Builder Designer/RDP for a wood truss project has not met the permanent bracing design responsibility defined by IBC referenced standard per ANSI/TPI 1–2014, Section 2.3.3.1.3.
ANSI/TPI 1–2014 addresses the case wherein a permanent bracing plan has not been provided:

2.3.3.2 Absence of Truss Restraint/Bracing Method or Details.
If a specific Truss member permanent bracing design for the roof or floor Framing Structural System is not provided by the Owner, Building Designer or any Registered Design Professional, the method of Permanent Individual Truss Member Restraint and Diagonal Bracing for the Truss Top Chord, Bottom Chord, and Web members shall be in accordance with BCSI-B3 or BCSI-B7.

4. A presentation of ANSI/TPI 1, Section 2.3.3.2, could open the door to presenting the content of the BCSI Book. CM customers can be encouraged to understand the importance of truss bracing (topics to help with that task will be listed shortly). The CM can also encourage the GC to provide BCSI permanent bracing information and details to the RDP for their potential use in preparing permanent bracing designs for their projects.

come back on Valentines Day for Part II of Frank Woeste’s discussion.

This entry was posted in Professional Engineer, Pole Barn Design, Building Department, Pole Buildings History and tagged Permanent truss bracing, building official, temporary truss bracing, 2015 BCSI Book, Stan Suddarth, ANSI/TPI 1 on February 9, 2023 by admin.

Under Construction Barn Collapse Close to Home

Under Construction Barn Collapse Close to Home

Summit, South Dakota is within an hour’s drive of Hansen Pole Buildings’ headquarters in Roberts County. In September 2022, this dairy barn (under construction) collapsed, sending 10 people to hospitals with injuries.

Many states, South Dakota included, allow agricultural buildings to be erected not only without being engineered, but also with no (or minimal) building permits being required.

I have previously authored articles regarding avoiding common building failures in the Post-Frame industry:

https://www.hansenpolebuildings.com/2014/04/nationwide/ and https://www.hansenpolebuildings.com/2014/04/nationwide-2/

Owners of a project with metal-plate-connected wood trusses spanning 60 feet and greater are now required to engage an RDP to design and inspect both temporary and permanent bracing for trusses (See International Building Code Sections 2303.4.1.3, 1704.6.2, and 1704)

Some industry professionals have weighed in upon this particular incident:

Jason Blenker (Drexel Building Supply):

“Even if you did 1/2 of what BCSI describes you would avoid many of these incidents. Seems like it’s an “all or nothing” proposition for many installers. Too many successful installs without an issue. Sad to see these happen, people just don’t understand the true forces at work.”

Geordie Secord (Northern Truss; Barrie, Ontario):

“In 30+ years in the truss business I’ve seen a couple dozen cases of trusses collapsing. All but one was during construction. The other was a 20 year old building exposed to record snow fall and rain. In every case, EVERY case, bracing was completely missing, or ridiculously inadequate compared to industry recommendations that have been common place for as long as I’ve been in the industry.”

Ivan Filchev (Structural Engineer at Flight Timber Products, Ltd):

“I have studied the matter before and in my opinion, there are regional building standards which, in certain cases, overestimate the capacities of the bracing.
Nevertheless, I agree with Jason Blenker that stability should be dealt with seriously every time and that underestimation of the magnitudes of the forces is very common among professionals in our industry.”

Mike the Pole Barn Guru (Hansen Pole Buildings)

In my humble opinion, there is a very simple solution to minimization of failures in agricultural buildings – require them to be built from site-specific engineered plans, acquire building permits and be subject to structural inspections.

This entry was posted in Trusses, Rebuilding Structures, Pole Barn Design, Building Department, Pole Barn Planning, Pole Barn Structure and tagged agricultural buildings, Permanent truss bracing, metal plate connected wood trusses, building permits, temporary truss bracing on February 2, 2023 by admin.

Reason You Go With Engineered Prints

Reason You Go With Engineered Prints

Yes, I know some of you gentle readers are offended by my harping on how important it is to build only from site specific fully engineered plans. Well, here is a case study.

Reader AARON in CARBON HILL writes:

“Reason you go with engineering prints. My contractor said it’s how we always do it. Well after they fell he said we need to discuss payment on the work I’ve done I paid for all material up front. I’m not paying c**p he should pay me for the lost and damages.”

As far as engineering goes, it appears columns have an unsupported length of under 131 inches.

Why would this be important?

For a roof only building, such as this, columns are carrying all of the bending loads from winds. Sound engineering practice, says wood column’s least dimension (5-1/2 inches) x 50 divided by Ke (2.1 in this instance) equals maximum unsupported length.

5.5” x 50 / 2.1 = 130.95”

K factor approximates length a column actually buckles at. This effective length can be longer, shorter or exact depending upon rigidity of supports. As a roof only structure has no means to transfer horizontal loads through endwall sheathing, columns act as cantilevers (think diving board). For a building with sufficient endwalls Ke would be 0.85 (makes a huge difference).

Truss carriers appear to be sketchy, however not having site loads, nor size, grade and species of them, it is impossible to verify (and none of them appear to have failed in photos provided).

What is absent? Temporary and permanent truss bracing.

I have expounded on how important temporary truss bracing is previously (https://www.hansenpolebuildings.com/2014/12/temporary-truss-bracing/). I advised Aaron this appeared to be the cause of his now firewood. Also – this one is on his builder, who has some cajones asking to be paid when he caused this mess.

AARON responded, “Yep thanks I just thought if anyone wanted to see what happens when your contractor doesn’t follow the prints. Feel free to share with anyone. We will be ordering a new building kit and go with a contractor with more references. Thanks.”

Currently, there is such a shortage of builders, every Chuck-With-A-Truck, a hammer, circular saw, big dog and loud radio seems to think they can hop in and make big money. Don’t be caught in Aaron’s situation – always thoroughly vet any contractor https://www.hansenpolebuildings.com/2018/04/vetting-building-contractor/.