Steel Truss Manual

Provided by

EASYSPAN Truss 8291 Mt. Vernon Rd.

St. Louisville, Ohio 43071

www.easyspantruss.com

Steel Truss Manual

EASYSPAN Truss Steel Truss Manual

11/25/2009 steel truss manual.doc

Copyright © 2009 EASYSPAN Truss All rights reserved. No part of the manual may be reproduced, by any means, without written permission of the authors. Disclaimer of liability: The authors shall have neither liability nor responsibility to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in this manual. While the manual is as accurate as the authors can make it, there may be errors, omissions and inaccuracies.


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Table of Content Introduction ...........................................................................................................6 Section 1 Preliminary information....................................................................7

1.a Safety Precautions .....................................................................................7 1.b Equipment ..................................................................................................7

Section 2 Overview of Construction ................................................................8 Section 3 Building Site ....................................................................................9

3.a Site Selection .............................................................................................9 3.b Site Preparation .......................................................................................10 3.c Material Delivery ......................................................................................10

Section 4 Post Placement .............................................................................11 4.a Squaring the Site......................................................................................11 4.b Footing Options........................................................................................16 4.c Drilling Holes ............................................................................................18 4.d Setting Posts ............................................................................................19

Section 5 Framing the Walls..........................................................................22 5.a Grade Boards...........................................................................................22 5.b L-girts .......................................................................................................24

Section 6 Trusses..........................................................................................26 6.a Delivery & Assembly ................................................................................26 6.b Lifting Trusses..........................................................................................27 6.c Gable Trusses..........................................................................................28

Section 7 Heritage Gables ............................................................................30 7.a Building the Heritage Gable .....................................................................30 7.b Locating EZClips ......................................................................................32 7.c Setting the Heritage Gable .......................................................................33

Section 8 Legacy Gable Trusses...................................................................34 8.a Setting the Legacy Gable .........................................................................34

Section 9 Intermediate Trusses.....................................................................37 9.a Cutting Post Tops.....................................................................................37 9.b Post Stubs................................................................................................37 9.c Setting Intermediate Trusses ...................................................................39

Section 10 Purlins ...........................................................................................40 Section 11 Bracing ..........................................................................................42

11.a X-bracing..................................................................................................42 11.b V-bracing..................................................................................................45



Table of Figures Figure 4-1 – Batter Boards 11 Figure 4-2 – Site Layout 12 Figure 4-3 – Initial String Placement 13 Figure 4-4 – Diagonal Dimension 14 Figure 4-5 – The 3-4-5 Method 15 Figure 4-6 - Footing Options 16 Figure 4-7 – Footing Options 17 Figure 4-8 – Locating Holes 18 Figure 4-9 – Adjusted Strings 19 Figure 4-10 – Corner Post Bracing 20 Figure 4-11 – Intermediate Post Bracing 21 Figure 5-1 – Grade Board Placement 22 Figure 5-2 – Grade board @ highest elevation 22 Figure 5-3 – Starting the Grade Board 23 Figure 5-4 – L-Girts 24 Figure 5-5 – L-Girt Placement 25 Figure 6-1 – Assembled truss with spacers 26 Figure 6-2 – Lifting a truss 27 Figure 6-3 – Heritage gable framing 28 Figure 6-4 – Legacy gable truss 29 Figure 7-1 – Heritage gable cuts (with 12” overhang) 31 Figure 7-2 – Heritage gable cuts (with no overhang) 31 Figure 7-3 – Girder placed on truss for marking 32 Figure 7-4 – Attaching EZClips 32 Figure 7-5 – Calculating gable girder placement 33 Figure 8-1 – Post bracket at Corner Post 34 Figure 8-2 – Steel Truss at Corner Post 35 Figure 8-3 – Gable Steel Truss at Intermediate Post 36 Figure 8-4 – Truss @ intermediate post detail 36 Figure 9-1 – Post Cut for Steel Truss 37 Figure 9-2 – Post stub over eave opening 38 Figure 9-3 – Post stub detail 38 Figure 9-4 – Intermediate Post Cap 39 Figure 9-5 – Intermediate Truss at Post/Post Stub 39 Figure 10-1 – First bay with trusses and purlins 40 Figure 10-2 – Purlin attachment detail 40 Figure 10-3 – Purlin Strapping 41 Figure 10-4 – Purlin Strapping detail 41 Figure 11-1 – X-bracing connection at peak 42 Figure 11-2 – X-bracing connection at eave 43 Figure 11-3 – Plan showing typical X-bracing layout 44 Figure 11-4 – Bending V-bracing in-place 48 Figure 11-5 – Bottom view of V-bracing 48



Figure 11-6 – Top view of V-bracing 49 Figure 11-7 – Sample Truss layout showing V-bracing 50



Introduction The purpose of this manual is to assist you in the erection of your post-frame building using EASYSPAN steel trusses. This manual will cover the post-frame constructions steps leading up to and including the attachment of your EASYSPAN trusses. If you already have your posts set and initial framing completed, you can advance directly to Section 6 which details how the EASYSPAN Trusses attaches to the framing. The step-by-step instructions and illustrations included here are not necessarily the only way to build a post-frame building. They do, however, comprise what feel are best practices for doing so. The tips and suggestions are the result from years of post-frame & construction experience, as well as feedback received from both customers and contractors. This manual is generic and assumes that other drawings or documentation was provided with your building package that contains specific dimensions and instructions for constructing your building. You will find the acronym ASID (as shown in drawings) used throughout this document reminding you to refer to your drawing set for specifics on a certain topic. In the event of any discrepancy between this manual and your drawings, the drawings should always take precedence.



Section 1 Preliminary information

1.a Safety Precautions Building your post-frame building is a challenging but rewarding experience. Making it a pleasurable and safe experience is important to us. The following precautions should be observed to insure that your construction project goes as smoothly and as safely as possible.

• Care should be taken to wear appropriate protective clothing; gloves, eye protection, steel-toed footwear, safety harnesses, etc.

• Take note of overhead electric lines before using ladders, cranes or lifts.

• While setting posts, all open post holes should be covered or marked off to prevent accidents from workers, children or animals

• Most metal panels will have sharp edges and should be handled carefully. Also, large panels can catch wind and become hard to handle.

Buildings under construction are vulnerable to high winds and can present a safety hazard. It is the responsibility of the erection/installation contractor (or customer) to recognize adverse weather conditions and take prompt and appropriate action to protect life and property.

1.b Equipment Minimum 1) Tape Measure 2) Framing square 3) Post-hole digger 4) Utility knife 5) Metal shears

6) Level 7) Ladders 8) Hammer 9) Wrenches/ratchets

Recommended

• Transit • Power hole auger with 18” (or larger) bit • Scaffolding • Nail gun



Section 2 Overview of Construction Constructing a post-frame building is not a difficult project, with proper preparation, attention to detail, and experienced guidance provided by this EASYSPAN Truss Construction manual. A typical post-frame construction project includes the following steps. 1) Prepare site 2) Layout & drill holes 3) Set posts & backfill holes 4) Attach grade boards, girts and girders 5) Set trusses and check building alignment 6) Add purlins and roof bracing 7) Add siding metal 8) Add roof metal 9) Add metal trim



Section 3 Building Site

3.a Site Selection It is likely that by the time you receive this manual, your site has already been selected and prepped. In the event that there is still some flexibility on your part as to the best location, we offer a few considerations. Ground Slope – The slope of the site will affect (1) the rainwater drainage around the building, and (2) the length of posts needed. When possible, select a site that will require as little excavation as possible.

Soil Type – The type of soil where you plan to construct your building can impact its lifespan. Sandy or continuously wet soil can be unstable to build on. Extremely rocky soil can make setting posts difficult & costly. Zoning Considerations – Check with local authorities for any restrictions regarding to types of buildings, building size, property setbacks, and other relevant codes. Other Structures – Take into consideration other buildings and/or structures (both on the ground and overhead) that could interfere with the construction or use of your new building. Take into consideration the delivery of materials, as well as heavy equipment access to the site.



3.b Site Preparation Once the site selection is finalized, it may need some preparation to make it suitable for both construction and the building itself. Grading – Prior to any construction, the site should be leveled as much as possible. This area will ultimately serve as either the floor in your new structure or the base for a concrete floor. It may be necessary to use heavy equipment to help with this task, such as a bulldozer, bobcat or similar. If the selected site is sloped, the highest corner will be used to establish your grade point of reference and will also be used to determine the placement of all grade boards (Refer to Section 5.a) Backfill – All posts need to be placed in virgin soil. If a site is sloped significantly, fill dirt will be needed to backfill the low areas to level the site, before holes can be dug for the posts. Backfill should be placed in 6”-8” layers, each compacted before adding the next. Drainage - If site has surrounding ground which slopes toward the building, it is recommended that ditches be dug to divert water away from the building’s foundation. This will help preserve the posts & flooring and keep the building’s contents dry. Gravel -

3.c Material Delivery Once the building site has been prepped, your building materials can be delivered. Contact your EASYSPAN distributor to coordinate the delivery schedule that works best for your project. Advance notice is recommended to ensure that all materials are available on the determined ship date. As the materials arrive, choose a storage location for them which will minimize any interference with construction and limit the need to move them as construction progresses.



Section 4 Post Placement Proper post placement is critical to an easily-constructible, well-built, and long-lasting post-frame building. This section details the steps for laying out and setting your posts.

4.a Squaring the Site Once the building’s site has been prepped, mark out the basic building footprint, starting at one corner and working your way around the perimeter of the building. Batter Boards - Batter boards can serve as fixed reference points for determining the exact placement of the corner posts. These boards can be easily built using scrap lumber and placed at each corner of the building.

Figure 4-1 – Batter Boards

Note: Batter boards should be made from scrap lumber. Do not use lumber that is intended for use during framing your building. This may cause shortages later in the project.



Once built, locate a set of batter boards at each corner of the proposed building site using the buildings overall width and length. Be sure to place the batter boards far enough away from the post locations to allow for digging post holes.

Figure 4-2 – Site Layout

Once in place, care should be taken not to bump or move these boards until posts are set and secured.



Stringing Boards – Strings should be strung between the batter boards to mark the overall footprint of the building. The strings will represent the outside of the structure’s framing, not the location of the posts. Note in Figure 4-3 that the stings are 1 ½” away from where the posts will be set. We will reposition the strings later before setting the posts.

Figure 4-3 – Initial String Placement



Squaring the Strings – In addition to the length and width of the building, a diagonal measurement between opposite corner posts is important in squaring your building. Refer to your building’s drawings for a diagonal measurement from corner post to corner post. It should be similar to what is shown below.

Figure 4-4 – Diagonal Dimension



In some cases, the building’s size may be too large to easily measure the diagonal distance. The “3-4-5 method” can be used to ensure that the strings and ultimately the building are square. At one corner, measure & mark 3’ on one string from where the strings cross. Then measure & mark 4’ on the other string. The distance between these two marks will be 5’ when the strings are “squared”. Adjust each string at the other end as necessary.

Figure 4-5 – The 3-4-5 Method



4.b Footing Options There are a number of footing options that can be used for your building. Some will be dictated by local codes. Below are four basic types of post footings along with our recommendations.

Tamped earth (not recommended) – This is the easiest footing type. The hole is simply filled & tamped after the post has been set. Since the post is resting on soil, some settling is likely to occur. This footing type is not recommended for post-frame buildings. Concrete Punch Pad (conditionally recommended) – This option provides a more stable base for the posts and prevents settling. Concrete is placed in bottom of hole to thickness stated in drawings. Concrete pads can either be poured directly into the open holes or preformed pads can be purchased and dropped into the holes prior to setting the post. Backfill the whole with dirt compacted every 6 to 8 inches with a spud bar or 2x4. This footing option is acceptable for small to medium size buildings which are fully enclosed because it does not provide any protection against uplift.

Figure 4-6 - Footing Options



Butt Enclosed (not recommended) – acceptable for Legacy buildings Full Encasement (recommended) – This option offers the most solid construction. It is especially recommended for open-ended buildings due to increased uplift caused by the open design. It requires some additional cost and effort, but can also reduce the depth at which posts need to be set. Concrete is placed in bottom of hole to thickness stated in drawings. Concrete pads can either be poured directly into the open holes or preformed pads can be purchased and dropped into the holes prior to setting the post.

Figure 4-7 – Footing Options



4.c Drilling Holes Locating Holes – Using a tape measure and a can of spray paint (fluorescent colored paint works best), mark on the ground where the center of each post is to be placed. The distance from the string to the center of the post (A) is found by adding half of the post size (B) to the 1 ½” setback (C) for the girts. (Figure 4-9)

Drilling Footing Holes – Use an 18” (or larger) auger bit to drill holes. Drilling oversized holes makes it easier to level and align posts. Holes should be 36” deep, unless specified otherwise on your drawings or by local code.

Figure 4-8 – Locating Holes

Note: Be sure to clear all loose dirt from the hole before setting the post.



4.d Setting Posts Adjust String Lines - Before setting the posts, restring the batter boards, moving the string “inward” 1 ½” all around. This will place the strings at the face of the posts, rather than at the girt line (compare with Figure 4-3). This will allow posts to be placed “against” the repositioned strings.

Figure 4-9 – Adjusted Strings

Note: When setting posts against the strings, be sure not to push the string. This will effect the placement of adjacent posts.

Note: All endwall (gable) posts should be oriented the same direction.



Mark Intermediate Post Locations – Use a bright colored marker or tape to mark on the string the location for each intermediate (i.e. non-corner) post. This will be more accurate than placing the post in the center of the hole. Refer to drawings for placement and dimensions of intermediate posts. Setting Corner Posts – Starting at one of the corners, set and level the first corner post, making sure that it touches both strings lightly. A “post level” (shown at right) is recommended for leveling posts easily & accurately. Attach braces by nailing one end of a 2x4 brace to the post and the other end to a stake in the ground. Continue this process for all other corner posts.

Figure 4-10 – Corner Post Bracing

Note: For buildings smaller than 40’ in length, braces are best placed on the outside of the building footprint to prevent them from getting in the way when setting trusses.



Setting Intermediate Posts – For intermediate (eave & gable) posts, be sure to align the middle of the post with the mark placed earlier (Section 4.d). Post should be braced immediately as each is set in place and leveled. Long 2x4s, supplied with the building kit, can be used as long as they are not cut. Once the post footings have cured, they will be removed and repurposed as framing members. For intermediate posts, attach one brace from the post to a stake in the ground. Attach the other brace to an adjacent, secured post.

Figure 4-11 – Intermediate Post Bracing

Securing Posts – Once a post is in place, the hole should be backfilled with dry dirt or concrete as shown in Section 4.b. Continue to check the post for plumb until hole is completely full. The top of the filled hole, whether it is soil or concrete, should be tapered away from the post to prevent water from collecting against the post.

Note: The “post-to-post” braces should be placed “inside” the building to minimize any interferance with girt placement on the outside of the posts.

Note: At the highest elevation of the site, verify that the distance from grade to top-of-post is sufficient to allow for girder placement (wood trusses). Check drawings for dimensions.



Section 5 Framing the Walls After the posts have been secured, it is best to let the concrete cure for a minimum of 12 hrs before beginning any framing.

5.a Grade Boards Placement - To find the location for the grade board, determine the height of the gravel base. This will be the bottom of the grade board. If there is to be a concrete floor, the bottom of the concrete will be the bottom of the grade board.

Figure 5-1 – Grade Board Placement

As noted in Section 3.b and shown in Figure 5-2, the site’s highest elevation should be used to establish your grade point-of-reference and the placement of your initial grade board.

Figure 5-2 – Grade board @ highest elevation



Once the grade board height is determined, place a mark on the nearest post at top of the grade board. Use a transit (or a straight 2x4x16 & level) to marks to all adjacent posts. Start the grade board at a corner post and allow it to extend past the post by 1 ½”. This will allow the corner to be flush as shown. Nail the grade boards with (4) 16d ring shank galvanized nails per end.

Figure 5-3 – Starting the Grade Board



5.b L-girts After the grade boards are in place, moving vertically up the posts, the L-girts (horizontal framing between posts) are the next framing members that will be added. Refer to drawings for proper spacing.

Figure 5-4 – L-Girts

If post braces interfere with the placement of a girt, the girt can be skipped until bracing is removed.

Note: Do not cut the tops off of any of the posts until the gable trusses or girders are in place.



Figure 5-5 – L-Girt Placement

Note: Only place L-girts up to the building’s height

(eave dimension). L-girts on the gable ends that are above the building height should only be attached after gable trusses are set.



Section 6 Trusses

6.a Delivery & Assembly Your EASYSPAN trusses will arrive in two or three sections, depending on the size of your building. Be sure to place the truss bundles so they are not in the way of construction (Section 3.c). Inspect the trusses after that have been dropped off. Do not use damaged trusses. The truss sections will need to be assembled using the provided hardware. As each truss is assembled, stack them using scrap lumber as spacers between trusses to protect the purlin clips.

Figure 6-1 – Assembled truss with spacers



6.b Lifting Trusses While trusses are engineered for handling roof loads, the process of lifting them can create stress that the trusses were not designed for. Adherence to the following guidelines is critical:

• Do not lift bundled trusses by the bands. • Do not attach cables, chains or hooks to the web members. • Do not lift trusses with spans greater than 30’ at their peak. The quantity of “lift points” is important to lifting the truss safely. Lift points should be spaced evenly across the truss, distributing the weight appropriately.

Truss Span Lift Points24’ - 36’ 1 40’ - 50’ 2 60’ - 70’ 3

80’ + 4

Lifting devices should be connected to the truss top chord with a closed-loop attachment utilizing materials such as slings, chains, cables, or nylon straps of sufficient strength to carry the weight of the truss. Each truss should be set in proper position per the building designer’s framing plan and held with the lifting device until the ends of the truss are securely fastened and all temporary bracing is installed.

Figure 6-2 – Lifting a truss



6.c Gable Trusses After the bracing and framing is completed, truss can be set, beginning with the gable (end) trusses. EASYSPAN offers two truss series, Legacy & Heritage. The primary difference is in how the gables are handled. With the Heritage Series trusses, the gable “truss” is constructed out of wood framing. EASYSPAN’s steel EZClips are attached to the framing to accept the purlins.

Figure 6-3 – Heritage gable framing

Note: Before setting any trusses, it is important to verify the “squareness” of your building.

If your building requires the Heritage gable framing, go to Section 7.



With the Legacy Series trusses, the gable truss is constructed similar to the other intermediate trusses, containing integrated clips to accept purlins.

Figure 6-4 – Legacy gable truss

If your building uses the Legacy gable truss, go to Section 8.



Section 7 Heritage Gables The trusses provided with the Heritage package are “interior” trusses only. The gable (endwall) “trusses” are actually girders, constructed out of lumber (as shown in Figure 6-3). These will be built to match the pitch of the EASYSPAN Heritage trusses that will be placed in the interior of the building.

7.a Building the Heritage Gable Framing the Heritage gables require precise cuts and measurements to ensure that the purlins align properly with the interior steel trusses. In this section, the examples and measurements used will be based on a typical 4/12 pitch for the trusses. Lumber Selection – The size of lumber that is used for the gable girder depends on the post spacing on the gable end of your building.

Post spacing Girder size 8’ o.c. 2x6 12’ o.c. 2x8 16’ o.c. 2x10

Table 7-1 – Heritage gable framing Sizes based on 20 lb ground snow load.



Girder Cuts – One end of the girders will need cut as shown in one of the two illustrations below, depending on your building’s overhang. (A full size template is provided to assist in laying out these cuts.) The other end of the girder will get a “plumb” cut.

Figure 7-1 – Heritage gable cuts (with 12” overhang)

Figure 7-2 – Heritage gable cuts (with no overhang)



7.b Locating EZClips Before installing the Heritage gable girders, the EZClips should be added. The placement of these clips should align with the purlin clips on your trusses. The easiest and surest ways to do this is to lay the gable girder on one of the trusses and mark the board where each of truss’s purlins clips are located.

Figure 7-3 – Girder placed on truss for marking

Once marked, the EZClips can be attached with the provided hardware.

Figure 7-4 – Attaching EZClips



7.c Setting the Heritage Gable Since the gable “truss” is being constructed from wood, setting it properly requires some calculations. The calculation will ensure that the angle and placement of the girder matches the angle of the steel trusses so that purlins can be attached properly. The formula below is a universal formula that will allow you find to a point on a gable post that will set the girder at the correct angle. G * P + H + B = D

G Distance from outside of girt to inside of post (in decimals of an inch) P Pitch (i.e. for 4/12 use 0.3333) H Heel height (typically 6”) B Building height (in decimals of an inch) D Distance from grade to point on post (in decimals of an inch)

Figure 7-5 – Calculating gable girder placement

Example: (G) Girt to post distance: 78.0” (6’-6”) (P) Pitch: 0.3333 (4/12) (H) Heel height: 6” (B) Building height: 144.0” (12’-0”)

Formula: 78.0 * 0.3333 + 6 + 144.0 = 175.9974” (15’-0”)

Note: If your building has an overhang (as shown above) make sure to allow for overhang distance when attaching gable girders.



Section 8 Legacy Gable Trusses

8.a Setting the Legacy Gable Steel gable trusses are placed on the inside of the gable posts (i.e. inside the building) resting on a “post bracket”. The post bracket is attached to the post with the lag bolts provided and the top of the bracket should be level with the top-most girt. The edge of the post bracket should be flush with the outside (eave) edge of the corner post. This will ensure proper placement of the truss.

Figure 8-1 – Post bracket at Corner Post



Gable trusses are placed by resting on the “seat” created by the post bracket. Secure the truss using the hardware provided.

Figure 8-2 – Steel Truss at Corner Post

(shown with optional overhang)



At intermediate gable posts, the truss is held against the post using the provided “post ties” and lag bolts. These post ties primarily serve to keep the truss upright against the post while the rest of the roof system (add’l trusses, purlins, and roof metal) is being erected.

Figure 8-3 – Gable Steel Truss at Intermediate Post

Figure 8-4 – Truss @ intermediate post detail



Section 9 Intermediate Trusses

9.a Cutting Post Tops Once the gable posts have been set, the tops of all posts can be cut. Intermediate sidewall posts are designed to rest directly on top of the posts, so they should be cut flush with the top of the top girt (as shown below). The gable posts can be cut just above the gable girder or the steel truss.

Figure 9-1 – Post Cut for Steel Truss

9.b Post Stubs Ideally, all intermediate trusses would rest (or bear) on a post. It is not uncommon, however, to have a truss that needs to rest where no post can be placed. For example, if a garage door doesn’t fit in between the building’s post (bay) spacing, it would not be acceptable to place a post in the door opening. In such conditions, “post stubs” are used to take the place of, and serve the purpose of, the post. Post stubs provide both weight transfer as well as uplift protection.



Figure 9-2 – Post stub over eave opening

The post stub should be the same size as the adjacent posts, and can often be made using the scraps from when the post tops were cut off.

Figure 9-3 – Post stub detail



9.c Setting Intermediate Trusses A post cap is required on the top of each post (or post stub) to provide an attachment for the steel truss. Attach the post cap such that the edge is against the top girt (i.e. flush with the outside of the post) using the hardware provided.

Figure 9-4 – Intermediate Post Cap

Once the post caps are in place on both sides of the building, the truss can be set (see Section Lifting Trusses6.b) and secured to the threaded studs on the post cap. If the building has an overhang, the properly positioned post cap will ensure the correct overhang distance.

Figure 9-5 – Intermediate Truss at Post/Post Stub

(shown with optional overhang)



Section 10 Purlins When the building’s first bay has both trusses, purlins can (and should) be added to begin giving the building its structural strength. A minimum of (4) purlins per side should be attached as each truss is set.

Figure 10-1 – First bay with trusses and purlins

Place purlins in the purlin clips and secure them using the hardware provided. Lumber for purlins should be 2100 Fb MSR (machine stress rated).

Figure 10-2 – Purlin attachment detail



Since the EASYSPAN truss makes it possible to have bay spacing up to 16’ o.c., the purlins may sag slightly prior to attaching the metal roofing. To prevent this, slotted banding is provided and should be attached on each bay half-way between trusses as shown below.

Figure 10-3 – Purlin Strapping

Figure 10-4 – Purlin Strapping detail

Purlins strapping is intended to go from one fascia board to the other. Strapping should start at one fascia board, go across the peak, and down to the opposite fascia board.



Section 11 Bracing

11.a X-bracing EASYSPAN trusses incorporate aircraft-grade roof cable x-bracing between trusses. Each truss is built with a slot (at eaves) and an attachment post (at peak) for the cabling.

At the peak, one end of the looped cable is secured to the post using the provided hardware.

Figure 11-1 – X-bracing connection at peak



At the eaves, the other end of the looped cable (with the eye bolt) is fed through the slot in the truss and through the hillside washer. A nut & washer are used on the eye bolt to tighten the X-bracing cable.

Figure 11-2 – X-bracing connection at eave



Bracing guidelines:

• End bays are typically un-braced, except in the case of small buildings with only (2) bays. In such cases, both bays should be braced.

• There should be no more than (3) adjacent bays un-braced. Refer to drawings for which bays should be braced.

• In high seismic areas, additional X-bracing may be required.

Figure 11-3 – Plan showing typical X-bracing layout

Note: Do not over-tighten X-bracing. This can cause purlins to buckle and throw the building out of square.

No more than (3) adjacent un-braced bays.

End bays typically

un-braced.

Braced bay.



11.b V-bracing In addition to the X-bracing, V-bracing is also used on each intermediate truss. V-bracing stabilizes the bottom chord of the truss by keeping it vertical. This bracing serves the same purpose as the lateral bracing used with wood trusses.



V-bracing is provided as straight stock which is bent against the bottom chord of the truss at the location designated on the Truss Layout drawing



(



Figure 11-7). Each side of the V-brace is attached to the purlin with 16d nails provided. The nails can be bent over on the back side of the purlin.

Figure 11-4 – Bending V-bracing in-place

Placement and spacing of V-bracing is specified in the drawings on the Truss Layout sheet.

Figure 11-5 – Bottom view of V-bracing



Figure 11-6 – Top view of V-bracing

Truss Size

“A” Spacing

“B” Spread

Quantity of braces

24’ 4’ 2’ 4 30’ 4’ 2’ 6 40’ 4’ 2’ 8 50’ 8’ 3’ 6 60’ 8’ 3’ 8 70’ 8’ 3’ 10

Table 11-1 – V-bracing Parameters



Figure 11-7 – Sample Truss layout showing V-bracing

Documents

Steel Truss Manual