PHOTO 1: View from Inside the Structure. Note the Rotation of the WSP, Failure at the Lower Leading Edge and Deformation of the Top Plate

Transcription

1 2009 International Residential Code (IRC) Braced Wall Panel Design Value Comparative Equivalency Testing Braced Wall Panel Design Values July 15, 2010 Introduction: SBCRI undertook 39 tests resulting in 78 30' braced wall lines being evaluated. For these tests, the SBCRI standard comparative equivalency 12'x30' IRC single-story test structure was used to assess the performance of a 2009 IRC-based structure. PHOTO 1: View from Inside the Structure. Note the Rotation of the WSP, Failure at the Lower Leading Edge and Deformation of the Top Plate PHOTO 2: Fasteners Tear Out at the Top of the Braced Wall Panel View all SBCA Tech Notes at SBCA 6300 Enterprise Lane Madison, WI / / (fax)

2 Full Scale Testing of a Building Constructed as Specified by the IRC: To learn as much as possible about the assumptions made by the ICC Ad-Hoc Wall Bracing (AHWB) Committee in crafting the IRC, SBCRI created a standard 12'x30' single-story building, built precisely as specified in the IRC. The initial testing used IRC Method Wood Structual Panel (WSP) braced wall lines. See the following reports for the testing approach, test details and the building specification used to establish SBCRI's standard comparative equivalency benchmarks: 1. Critical Concepts Surrounding Deployment of ASTM E72, E564 and E2126 to Establish IRC/IBC Braced Wall Panel Design Values 2. Creation of the SBCRI Standard Comparative Equivalency Test Structure A 12'x30' IRC Single- Story Building 3. Specifications for the SBCRI Standard Comparative Equivalency Test Structure A 12'x30' IRC Single-Story Building 4. Background on the Development of the 2009 International Residential Code (IRC) Braced Wall Panel Section 5. Detailed test reports of each test will be placed on the IRC wall panel testing web page. Reports are currently available by contacting SBCRI at testdata@sbcri.info or by calling Emily at FIGURE 1: 3D Representation of Test Setup This setup represents the lower bound of the IRC braced wall panel Method WSP using 3 /8" OSB for the bracing panels located near the maximum allowed distance from the ends of the braced wall line per IRC Section R Testing was performed using ASTM E564 procedures and resulted in a two 30' shear wall/four braced wall panel average ultimate load of 367 PLF 1. 1 IRC Braced Wall Panel Testing in a 12' by 30' Full Scale Building Method WSP Constructed Braced Wall Panel System Performance Under Laterally Applied Monotonic Loading (WSP 3 /8" Test), SBCRI Test Report # SBCRI SBCA Tech Notes Page 2

3 The IRC assumption for Method 3 braced wall panels (without gypsum) is that the braced wall panel has a capacity of 500 PLF (prior to adjustments for partial restraint and/or systems effects). Therefore, to calibrate the SBCRI full scale test of a building constructed as specified by the IRC, an Actual Building Calibration Factor (ABC Factor) was created for each comparative equivalency test undertaken. This ABC Factor is defined as the IRC wall value divided by the tested value. For example, the IRC defines the baseline WSP wall as follows: FIGURE 2: IRC Maximum End Distance for Braced Wall Panels and IRC Table R WSP Application Defined SBCRI testing defines the Actual Building Calibration Factor as: SBCRI Comparative Equivalency Test # SBCRI Description of Wall Tested IRC 3 /8" WSP 6d 6 /12 Restraint IRC anchor bolts, trusses and actual roof dead load (sheathing and ceiling gypsum) Actual Building Test Average Ultimate Load (PLF) TABLE 1: Definition of Actual Building Calibration Factor (ABC Factor) IRC Assumed Load w/ Full Restraint (PLF) Full Scale Building to IRC Design Value Calibration Factor Similarly, the ultimate PLF loads in the table below are used as the basis for comparing the test results that follow: Ultimate Load Summary Basis of Comparison Description Sheathing Type Sheathing Location Sheathing Fastener Type Sheathing Fastener Spacing Restraint Interior Gypsum Ultimate PLF Load Intermittent WSP (Method 3) IRC basis 3 /8" WSP Any permitted 6d (0.113 x 2") 6 /12 Fully Restrained No Wood-Frame Shear Wall SDPWS basis 3 /8" WSP - 6d (0.113 x 2") 6 /12 Fully Restrained No Wood-Frame Shear Wall SDPWS basis 7 /16" WSP - 8d (0.131 x 2-1 /2") 6 Fully /12 Restrained TABLE 2: Ultimate PLF Loads Used as the Basis for Comparing Test Results No Table 1 from The Story Behind the 2009 IRC Wall Bracing Provisions (Part 2, Wind Bracing Requirements), Jay H. Crandell, P.E., ARES Consulting Zeno A. Martin, P.E., WJE Assoc., Wood Design Focus continuation of previous article, Vol. 17, No. 2, Summer SDPWS, Table 4.3A value adjusted for SPF lumber per footnote 3 (table value x 0.92 = adjusted value) 4 SDPWS, Table 4.3A value adjusted for SPF lumber per footnote 3 (table value x 0.92 = adjusted value) SBCA Tech Notes Page 3

4 SBCRI has undertaken the following matrix of IRC/SDPWS benchmark tests: Ultimate Load Summary Table of Wall Types Tested SBCRI Comparative Equivalency Test # Sheathing Type Sheathing Location Sheathing Fastener Type Sheathing Fastener Spacing Restraint Interior Gypsum5 Ultimate PLF Load SBCRI SBCRI a SBCRI b 3 /8" WSP 7 /16" WSP 6' from corners 6 6' from corners 6d (0.113 x 2") 6 /12 8d (0.131 x 2-1 /2") 6 /12 SBCRI /16" WSP At Corners 8d (0.131 x 2-1 /2") 6 /12 Partial - Full Building Dead Load, IRC Anchor Bolts Partial - Full Building Dead Load, IRC Anchor Bolts Partial - Full Building Dead Load, IRC Anchor Bolts No 367 No 412 No 426 SBCRI /16" WSP 6' from corners 8d (0.131 x 2-1 /2") 6 /12 Fully Restrained No 626 TABLE 3: Ultimate Load Summary Table of Wall Types Tested Given the above matrix of ASTM E564 testing where each test was performed on two 30' shear wall/four braced wall panels, the following IRC/SDPWS calibration factors have been developed: Calibration Factors Comparing SBCRI Full Scale Building Tests to IRC/SDPWS Design Values Using 3 /8" OSB as the Basis (IRC value of 500 PLF/SDPWS of 515 PLF) Test Description IRC 3 /8" WSP 6d 6 6' from corner Test # SBCRI IRC 7 /16" WSP 8d 6 6' from corner Test # SBCRI a Test # SBCRI b IRC 7 /16" WSP 8d 6 corner Test # SBCRI IRC 7 /16" WSP 8d 6 6' from corner with hold downs Test # SBCRI Ultimate PLF Load (unrestrained and restrained) Full Scale Building to IRC Design Value (500 PLF) Calibration Factor Full Scale Building to SDPWS Restrained Design Value (515 PLF) Calibration Factor 3 /8" WSP Basis /500 = /515 = /500 = /515 = /500 = /515 = /500 = /515 = 1.2 TABLE 4: Calibration Factors Comparing SBCRI Full Scale Building Tests to IRC/SDPWS Design Values Using 3 /8" OSB as the Basis (IRC value of 500 PLF/SDPWS of 515 PLF) 5 If Interior sheathing was indicated as Yes, ½" gypsum is applied along the entire 30' braced wall lines in accordance with IRC Table R and Section R Sheathing installed 64" from one corner and 72" from opposite end. For all other tests, WSPs were installed symmetrically at 6' from each end. SBCA Tech Notes Page 4

5 Calibration Factors Comparing SBCRI Full Scale Building Tests to IRC/SDPWS Design Values Using 7 /16" OSB as the Basis (SDPWS value of 672 PLF) Test Description Ultimate PLF Load (unrestrained and restrained) Full Scale Building to SDPWS Design Value (672 PLF) Calibration Factor 7 /16" WSP Basis IRC 3 /8" WSP 6d 6 6' from corner Test # SBCRI IRC 7 /16" WSP 8d 6 6' from corner Test # SBCRI a Test # SBCRI b IRC 7 /16" WSP 8d 6 corner Test # SBCRI IRC 7 /16" WSP 8d 6 6' from corner with hold downs Test # SBCRI /672 = /672 = /672 = /672 = 0.9 TABLE 5: Calibration Factors Comparing SBCRI Full Scale Building Tests to IRC/SDPWS Design Values Using 7 /16" OSB as the Basis (SDPWS value of 672 PLF) Calibration Factors Comparing SBCRI Full Scale Building Tests Test Description Ultimate PLF Load (unrestrained and restrained) Full Scale Building Partial Restraint to Full Scale Building Full Restraint Factor Full Scale Unrestrained 3 /8" OSB performance to full scale 7 /16" OSB performance built per IRC Full Scale 7 /16" OSB performance to full scale unrestrained 3 /8" OSB performance built per IRC IRC 3 /8" WSP 6d 6 6' from corner Test # SBCRI IRC 7 /16" WSP 8d 6 6' from corner Test # SBCRI a Test # SBCRI b IRC 7 /16" WSP 8d 6 corner Test # SBCRI /626 = /626 = /412 = /367 = /626 = /426 = /367 = 1.2 IRC 7 /16" WSP 8d 6 6' from corner with hold downs Test # SBCRI /626 = /367 = 1.7 TABLE 6: Calibration Factors Comparing SBCRI Full Scale Building Tests The SBCRI testing shows that the AHWB Committee made the best judgments it could given the data at its disposal. The SBCRI full scale building testing a building constructed as prescribed by the IRC having two 30' braced wall lines containing four braced wall panels has created a series of benchmark equivalency factors that could be viewed as a combination of a partial restraint factor and a systems effect factor. SBCA Tech Notes Page 5

6 Given all of this, SBCRI, as an ANSI/ACLASS approved agency as defined in the IRC/IBC, has established an equivalency testing procedure by performing ASTM E564-based whole building testing. The purpose of this testing is to provide data in accordance with the following code language found in both the IRC and IBC: R Alternative materials, design and methods of construction and equipment. The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code. Compliance with the specific performance-based provisions of the International Codes in lieu of specific requirements of this code shall also be permitted as an alternate. R Tests. Whenever there is insufficient evidence of compliance with the provisions of this code, or evidence that a material or method does not conform to the requirements of this code, or in order to substantiate claims for alternative materials or methods, the building official shall have the authority to require tests as evidence of compliance to be made at no expense to the jurisdiction. Test methods shall be as specified in this code or by other recognized test standards. In the absence of recognized and accepted test methods, the building official shall approve the testing procedures. Tests shall be performed by an approved agency. Reports of such tests shall be retained by the building official for the period required for retention of public records. Therefore, the SBCRI 12'x30' building tests: 1. Establish ASTM E564 ultimate strength values for benchmark IRC braced wall panel systems. a. From these established ultimate strength values, allowable design values can be determined from SDPWS counsel of dividing the ultimate strength test data by a factor of two. 2. Provide a pathway for new product development where comparisons can be made through testing that provides an accurate, and technically sound, level playing field. SBCRI testing provides a benchmark to compare equivalent performance to: a. IRC prescriptive braced wall panel and portal applications found in IRC Section R602.10, as specifically defined in IRC Table R b. SDPWS series of shear wall design values found in Table 4.3A (see Appendix B) c. WSP braced wall panels using hold down connection systems d. Any type of braced wall panel that makes up a shear wall i. It is now easy to compare performance of a wide variety of braced wall panel configurations using the specific construction specifications for the application. 3. Provide the equivalency characteristics/factors found in the previous tables and establish the partial restraint factor in the full scale building as shown in the table below. Test Description Ultimate PLF Load (unrestrained) Full Scale Building Partial Restraint Compared to Full Scale Building Full Restraint (626 PLF) IRC 7 /16" WSP 8d 6 6' from corner Test # SBCRI a Test # SBCRI b IRC 7 /16" WSP 8d 6 corner Test # SBCRI /626 = /626 = 0.7 TABLE 7: Full Scale Building Partial Restraint Compared to Full Scale Building Full Restraint SBCA Tech Notes Page 6

7 Summary: This test data suggests the following concepts: 1. The restraint-to-partial-restraint factor is The calibration factor to convert 3 / 8 " OSB performance to 7 / 16 " OSB performance is: a. 1.1 for unrestrained applications 7 b. 1.7 for unrestrained to restrained 8 3. For proprietary product development, calibration factors can be used to determine IRC equivalents. a. If the test data finds that the proprietary product is equal to or better than 3 / 8 " OSB installed as specified in the IRC, the IRC design values for that proprietary product installed per its installation instructions follow: Calibration Factors to take SBCRI Full Scale Building Tests to an equivalent IRC/SDPWS Design Value (IRC value of 500 PLF/SDPWS of 515 PLF for 3 /8"and 672 PLF for 7 /16") Test Description Ultimate PLF Load (unrestrained and restrained) Full Scale Building to IRC Design Value (500 PLF) Calibration Factor Full Scale Building to SDPWS Restrained Design Value (515 PLF) Calibration Factor 3 /8" WSP Basis IRC 3 /8" WSP 6d 6 6' from corner Test # SBCRI IRC 7 /16" WSP 8d 6 6' from corner Test # SBCRI a Test # SBCRI b IRC 7 /16" WSP 8d 6 corner Test # SBCRI IRC 7 /16" WSP 8d 6 6' from corner with hold downs Test # SBCRI /367 = /367 = /412 = /426 = /626 = 1.1 TABLE 7: Calibration Factors to take SBCRI Full Scale Building Tests to an equivalent IRC/SDPWS Design Value (IRC value of 500 PLF/SDPWS of 515 PLF for 3 /8"and 672 PLF for 7 /16") PLF / 367 PLF PLF / 367 PLF 1.7 SBCA Tech Notes Page 7

8 Appendix A: SBCRI-Wall 1 Test Setup and Connection Criteria SBCA Tech Notes Page 8

9 Appendix B: SDPWS Table 4.3A Nominal Unit Shear Capacities for Wood-Frame Shear Walls SBCA Tech Notes Page 9

10 Appendix C: Summary of Connections The following table summarizes the requirements for connecting various members of wall assemblies. Connection Location IRC Connection Requirement IRC Code Section Connection Used for Testing Reason for Deviation Notes Roof sheathing to trusses 8d common (2-1 /2 x 6/12 spacing Minimum thickness for 24" oc framing is: 3 PSF live, 7 40 PSF live and 1 70 PSF live. (All assume 10 PSF dead) R803.2, Table R602.3(1), Table R (1) 8d sinker (2-3 /8" x 6/12 spacing Available hand driven nail purchased locally Truss to perpendicular wall very top plate (2) 16d box nails (3-1 /2" x 0.135"). For trusses, approved connections with at least 175 lbs capacity. Table R602.3(1), R , R (3) 16d (3-1 /4" x 0.131") Available hand driven nail purchased locally The 2012 IRC changes this to (3) 16d nails and removes the truss specific requirement in 2009 IRC R Truss to parallel wall very top plate. No provision for general construction. At braced wall 6 in. oc (2-1 /2" x 0.131") Figure R (2) No provision for general construction. At braced wall 6 in. oc (2-1 /2" x 0.131") Where the uplift is greater than 100 PLF, an alternate connection is required per 2009 IRC R Very top plate to top plate Face nail, 10d (3" x 24" oc Table R602.3(1) Face nail, 10d (3" x 24" oc Offset of top plate ends Top plate overlaps at corners and intersections. 48" offset with (8) 16d (3-1 /2" x 0.135") nails in the overlapped area. Face nail, (2) 10d (3" x 0.128") Table R602.3(1) Table R602.3(1) 48" offset with (8) 16d (3-1 /2" x 0.135") nails in the overlapped area. Face nail, (2) 10d (3" x 0.128") WFCM allows a 30" offset (minimum 5' splice plate) Top plate to Studs (2) 16d (3-1 /2" x 0.135") nails Table R602.3(1) (3) 3-1 /4" x 0.131" pneumatic nails. Nails for framing guns are not available in the larger size. Sole plate to Studs (end nailed) Stud to stud connection (built up corners and double studs) Wall Sheathing to framing (2) 16d (3-1 /2" x 0.135") nails Table R602.3(1) 10d (3" x 24" oc 3 /8" WSP fastened with 6d (2" x 0.113") 6' oc at panel edges and 12" oc in the field Table R602.3(1) (3) 3-1 /4" x 0.131" pneumatic nails. 10d (3" x 24" oc. 3 /8" OSB fastened with 6d (2-3 /8" x 0.113") 6' oc at panel edges and 12" oc in the field Nails for framing guns are not available in the larger size. Wood sole plates to foundation 1 /2" anchor bolts with nut and washer (no size given), 6' oc, first bolt no more than 12" or less than 7 dia. (3-1 /2") from end. Extend 7" minimum into concrete. R , SDPWS , C & Appendix A2 5 /8" anchor bolt. Use 3" x 3" x 0.229" plate washer for the unrestrained condition Needed for fixture. May use other anchorage with other spacing s equivalent to the 1 /2" requirement SBCA Tech Notes Page 10

11 Appendix D: 2009 IRC Table R602.3 (1) SBCA Tech Notes Page 11

12 SBCA Tech Notes Page 12