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Rethinking Ways to Encourage Permanent Truss Bracing

Today’s blog comes from Hansen Pole Building’s guest, Frank Woeste, P.E.

Rethinking Ways to Encourage Permanent Truss Bracing Part II

  1. Truss Bracing Background

    The purpose of permanent truss bracing is to satisfy the design assumptions of the truss designer such that the truss system will safely support design loads through the design life of the structure. Early truss industry temporary bracing recommendations (DSB-89)[3] were based on an assumed dead loading of about 5–10 psf based on the truss span, whereas the truss design total load (gravity) commonly varies from 40–60 psf.

    The dramatic difference in assumed load levels acting during truss installation verses in-service loading is helpful in understanding that the bracing needed for a “safe installation” is only the first part of a complete truss system that will satisfy the design assumptions of the truss designer/engineer.

    2015 BCSI, pp. 1–36, provides background, data, and recommendations for the “safe installation” of trusses spaced up to 2-ft. on-center and up to 80-ft in length. After a quick review of these 36 pages, some GCs may be surprised by the extent of the information and then entertain the book as a “check-it-out item” for their truss installation sub-contractors.
     
  1. BCSI–B3 Discussion Topics—Permanent Bracing for Chords and Webs

    In the interest of time, only the “high points” can be covered to generate interest in the scope of the book. It may be instructive to review the bottom paragraph of the 2nd column on page 37:
    It can be quickly noted that, for most commercial projects involving an Architect or Structural Engineer (RDP), the roof truss bracing system design/specifications is not the responsibility of the Contractor per ANSI/TPI 1–2015, Section 2.3.4.10.

    As you page through the book with your customer, I believe some will be fascinated by the extent of information and bracing details available for consideration and possible use by the RDP for a project.

    Turning to page 41 on Web Member Permanent Bracing, you will find a discussion about the importance of Diagonal Braces (DBs) and Continuous Lateral Restraints (CLRs). Figure B3–11 then depicts CLRs in green, DBs in red. A note in two locations on page 41 states:
    “Repeat Diagonal Bracing every 20’ or as specified. Closer spacing may be required by the Building Designer.”

    A similar note is given in other locations of BCSI–B3 and it points to the fact that industry and engineering experts can only publish an upper limit on the DB spacing—not the actual spacing that might be required due to the design level of axial compression in a web or chord (typically produced by a design snow load combination).

    Returning to the case where the RDP does not provide a permanent bracing design for a truss package after it has been reviewed and returned to the CM, the GC must understand the RDP has not provided a definitive specification on the required DB spacing for the roof truss installation as required by the building code and TPI 1 (because BCSI–B3 defers the issue of DB spacing to the RDP).

    This discussion leads me to an “a-ha moment”—if the RDP for the project was advised about the availability of the BCSI Book and introduced to the permanent bracing content, would it be unreasonably burdensome to ask the RDP to:
  • Consider the BCSI Book as an industry standard for permanent bracing and possibly adopt it for a specific project,
  • Make notes in the book as to what is needed in terms of DB spacing(s),
  • Note any other additional permanent bracing requirements for the project,
  • Sign, seal, and add their professional work to the Construction Documents?

A Call to Action

This article suggests the idea that CMs should become more proactive in the education of their customers with respect to permanent bracing resources and the same information can be shared with the RDP for their specific project. The issue of permanent bracing design and installation is present for every truss installation based on the assumptions, bracing requirements, and information given on the truss design drawings. The natural link between the CM, GC, and RDP is the only link that I can identify whereby permanent bracing education by one party could be reliably shared with the other parties. Additionally, the CM could meet with local code departments and design professionals and provide a copy of the BCSI Book.

By this article, I challenge CMs and truss industry leaders to consider the current permanent bracing practices in the field and suggest other proactive ideas to establish a reliable path for sharing permanent bracing design resources with the GC and ultimately the RDP.

The author welcomes comments and can be contacted by e-mail: fwoeste@vt.edu.

[1] Building Component Safety Information 2013 Edition Updated March 2105 published by the Truss Plate Institute (TPI) and Structural Building Components Association (SBCA).

[2] http://www.tpinst.org/technical-downloads

[3] DSB-89: Recommended Design Specification for Temporary Bracing of Metal Plate Connected Wood Trusses published by the Truss Plate Institute (TPI).

This entry was posted in Pole Barn Planning, Trusses, Professional Engineer, Pole Barn Design, Building Styles and Designs and tagged , , , , on by .

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:

  1. 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.
     
  2. 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.
     
  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 Building Department, Pole Buildings History, Professional Engineer, Pole Barn Design and tagged , , , , , on by .

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 Pole Barn Planning, Pole Barn Structure, Trusses, Rebuilding Structures, Pole Barn Design, Building Department and tagged , , , , on by .

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/.

This entry was posted in Building Contractor, Trusses, Columns, Pole Barn Questions, Pole Barn Planning and tagged , , , , , , on by .

Permanent Truss Bracing

I have to give a lot of credit to Building Department plan checkers and field inspectors. They have to know a lot of stuff, about a myriad of different areas of construction. Even one who is an expert at what is written in the Building Code itself, would be only fluent in a small portion of what it takes to construct a Code conforming building, as the Building Codes now reference a litany of other publications and documents. Think of it as being similar to the IRS income tax code.

Puts it into perspective, doesn’t it?

truss bracingPrefabricated roof truss drawings (provided by the roof truss manufacturers) give the recommendation for how the truss designer feels the trusses should be braced, however the ultimate design of the truss bracing system, is the responsibility of the building designer (registered design professional – engineer or architect).

Recently one of our clients advised our office of the request, from their building inspector, for an email or letter from the engineer of record on their new Hansen post frame building. The request was in regards to the truss bracing system designed by the engineer superseding the bracing shown on the roof truss drawings.

Although the following may sound like it is in a foreign language, on the first page of the engineered building plans is a series of “General Notes”. Note 9 says:

“PER ANSI/TPI 1-2007 SECTION 2.3.2.3 TRUSS SUBMITTALS HAVE BEEN REVIEWED AND ARE FOUND TO BE IN GENERAL CONFORMANCE WITH THE DESIGN OF THE BUILDING. THE PERMANENT LATERAL BRACING HEREIN MEETS THE REQUIREMENTS OF ANSI/TPI 1-2007 SECTION 2.3.3.2”

ANSI/TPI 1-2007 pretty much lays out who does what and how. Here are some relevant excerpts:

2.3.2.5 Responsibility Exemptions.
The Registered Design Professional for the Building is responsible for items listed in 2.3.2, and is not responsible for the requirements of other parties specified outside of Section 2.3.2.

2.3.3.1 Method of Restraint.
The method of Permanent Individual Truss Member Restraint/Bracing and the method of anchoring or restraining to prevent lateral movement of all Truss members acting together as a system shall be accomplished by:

2.3.3.2 Method Specified by 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 permitted to be specified by any Registered Design Professional.

On this particular project, general note 9 covered the permanent lateral truss bracing system and is sealed by the Engineer of Record. This makes the request for an Email or letter from the engineer to cover the same topic redundant, as well as an unneeded expense to the building owners (engineers do not just do work for free).

Potentially, the building inspector could decide to alter the truss bracing system designed by the Engineer of Record, however this opens up an entirely new can of worms. In making an alteration, the inspector could be in violation of the laws which govern engineers, as well as placing the jurisdiction in a liability situation should a failure occur.

This entry was posted in Trusses and tagged , , , on by .
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