[American Society of Civil Engineers Structures Congress 2011 - Las Vegas, Nevada, United States...

1

Effect of Support Restraint on Wood-to-Wood, Joist Hanger Connection

William T. Bolduc, P.E., S.E., M. ASCE1 and Samaan Ladkany, P.E., Ph.D.2

1Keymark Enterprises, LLC, Engineering/Software Development, 6707 Winchester Circle, Boulder, CO 80301; PH (702) 481-0742; FAX (303) 443-9054; email: [email protected] 2Howard R. Hughes College of Engineering, Department of Civil and Environmental Engineering, University of Nevada Las Vegas, Box 454015, 4505 S. Maryland Parkway, Las Vegas, NV 89154-4015; PH (702) 301-7895; FAX (702) 895-3936; email: [email protected]

ABSTRACT

A common model of light gauge, metal joist hanger is tested on a wood-to-wood connection for two conditions. One condition follows the commonly used test standard for joist hangers, which allows the support beam to be restrained from horizontal and rotational movement. The second condition (unrestrained) allows the support beam to freely move horizontally and in rotation. The results show that the unrestrained case is much weaker than the standard restrained case. For the model of hanger tested, the average ultimate load for the unrestrained case was 28% of the standard restrained case. The mode of failure for the unrestrained case is different than that for the restrained case. This documents the importance of providing means of restraining the supporting beam by methods other than the connection via the joist hanger. The ASTM testing method for joist hangers may need to be adjusted to account for this possible mode of failure.

INTRODUCTION

Light gauge, metal joist hangers are widely used in wood frame construction in North America and in many areas of the world that use light wood frame construction. Most modern homes, apartments, and light commercial buildings that use light wood frame construction will also use joist hangers to connect framing members to supporting beams. A joist hanger is commonly used to connect a floor joist to a wood beam. Another common use is to connect a wood truss to a heavier “girder” truss. Although they are commonly called joist hangers, it is likely that nearly half of the usage is in roof framing, which are most commonly wood roof trusses. One of the main benefits of the joist hanger connection is that it connects to the side of the supporting beam or girder truss. This allows the supported framing member to be at the same elevation as the supporting beam or girder truss.

636Structures Congress 2011 © ASCE 2011

Structures Congress 2011

Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

2

The use of joist hangers allows the supporting beams to be flush with the supported framing. This allows for ceilings to be free of beams placed below the ceiling level. In many cases, the architectural advantage of using joist hangers justifies the small added cost. There are also architectural trends that encourage more complex framing and more open spaces. These trends require more support beams, trusses, and engineered lumber products, all of which require greater usage of joist hangers.

The trend to more complex designs and larger open spaces increases the occurrences of joist hangers that need to carry larger loads. The manufacturers of joist hangers have developed extensive arrays of joist hanger models for various geometric conditions and load capacities. A catalog from a major hanger supplier has over 70 pages devoted to joist hangers. Some of the joist hangers can be called beam hangers or girder hangers due to the large size and load capacity.

The author has been involved in the design of wood framing for many buildings that use very complex framing to achieve the architectural requirements. The most complex cases often involve roof framing with various hips, valleys, and roof openings. These requirements often cause framing from common trusses to be supported by a girder truss. In complex cases, one end of the girder truss is then supported by another girder truss, which is then supported by a third girder truss. See Figure 1.

Figure 1. Complex (4th order) roof framing: wood trusses connected by hangers

In each case joist hangers are used to transfer the increasing loads from truss to truss. This “fourth order” framing is unusual, but becoming more common. Third order framing is not difficult to find. Second order framing occurs on most wood frame



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

3

buildings that are larger than a simple box ranch home. All of this results in increased usage of joist hangers in more heavily loaded and more critical connections.

MOVEMENT AND RESTRAINT ON SUPPORTING MEMBERS

The purpose of this research is to test the effect of support restraints on the capacity of a joist hanger connection. In actual applications the supporting member of a joist hanger is commonly a wood beam or the bottom chord of a girder truss. The supporting member is always restrained from movement to some degree. The supporting member is always restrained from moving downward by the stiffness of the beam or girder truss and the supports for the beam or girder truss. This vertical restraint is the primary restraint in the direction of load.

Secondarily, the beam or girder truss has some restraint from lateral movement (perpendicular to the beam; in the longitudinal direction of the joist). Thirdly, the beam or girder has some restrain against rotation in the plane of the joist. Movement of the supporting beam in other directions is not usually considered to be related to the downward movement from gravity loads on a joist hanger connection and is not considered in this research.

One of the primary means of providing the secondary lateral restraint and the third rotational constraint is by the connection of the supporting member to the supported joist. The supported joist or truss is usually very stiff in the longitudinal direction of the joist and quite stiff in rotation in the plane of the joist. Other building elements that are connected to the beam or girder may also provide some lateral and rotational constraints.

In actual construction, the degree of restraint provided by these other building elements has great variability. The case of a roof truss supported by a girder truss at a location away from the supports of the girder truss may have very little lateral and rotational restraint. In some cases the main restraint is provided by an attached gypsum board ceiling. In other cases the ceiling is suspended, and the truss bracing is the main constraint.

One common condition is when floor decking is directly attached to the beam or girder. The floor decking may provide substantial lateral restraint and some rotational restraint when combined with other building elements. The connections of the beam or girder at the supports in combination with the lateral stiffness and torsional stiffness of the beam or girder also provide some restraint.

This research compares two cases. In one case the supporting beam of a joist hanger connection is restrained from lateral and rotational movement by blocking and metal rods. In another case the only restraint on the supporting beam is from the joist and



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

4

the joist hanger connection. The hypothesis is that the downward load capacity of the joist hanger will be significantly less when no additional restraints are provided to the connection.

REVIEW OF TESTING STANDARDS AND CODE APPROVALS

The current standard for testing joist hangers in North America is ASTM D 7147-05. This standard also provides a method of assigning the allowable loads for joist hangers.

The standard test method loads a joist that is connected to beams (or headers) at each end. Blocking and tensile reinforcement against the blocking is used to restrain the beams from lateral and rotational movement. A 3.18 mm (1/8 inch) minimum gap is specified between the joist and the beam before loading. See Figure 2.

Figure 2. Standard test set-up with the actual dimensions used (restrained)

The allowable joist hanger load (for normal load duration) is specified as the lesser of the following:

The average ultimate load per joist hanger divided by 3.0, when six or more tests are performed.

The lowest ultimate load per joist hanger divided by 3.0, when less than six (but at least three) tests are performed.

The average load per joist hanger at which the measured vertical deflection is at 3.18 mm (0.125 inches).

The test method is based on a short term test. The test method specifies the rate of movement of the test machine crosshead of between 0.8 to 5.1 mm (0.03 and 0.20 in.)



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

5

per minute. The ultimate load shall not be reached in less than 5 minutes. Although the test standard uses an ultimate design value divided by 3.0, the actual safety factor is much less than 3.0, after adjusting the short term test results to a normal (ten year) duration of load.

The allowable joist hanger load is also not allowed to exceed a calculated load based on the allowable values of the steel in the joist hanger and the allowable values for the fasteners used in the connection. An addition limitation is based on the calculation of wood bearing and fasteners of the joist bearing on the seat of the hanger.

Design values for joist hangers are not listed in the 2009 International Building Code (IBC). The use of joist hangers in the United States is usually based on the acceptance by the Building Official of an evaluation report. Evaluation reports are commonly produced by the ICC Evaluation Service, Inc. (ICC-ES) or other recognized agencies that perform technical evaluations of building products. In almost all cases, the test report for a joist hanger is produced and owned by the manufacturer of the joist hanger. The actual test reports are considered to be confidential and are not published. The test reports and other materials are submitted to the evaluation agency as justification of the design values listed in the published evaluation report. Although much testing is performed on joist hangers, very little information is published on the subject of testing joist hangers.

MATERIALS USED

The lumber, joist hangers, and nails used were purchased at retail building supply outlets. Both the lumber and the joist hangers were purchased at two different companies. The quality of both lumber and joist hangers appeared similar at both sources.

A commonly used hanger model was chosen for testing to represent the “middle of the field”. Size and load capacity was also selected to fit the available testing equipment. A “face mount” hanger was selected. A face mount hanger has no top flange, so all load must be transferred to the supporting beam by the fasteners.

The joist hanger selected was a Model HUS26 manufactured by one of the major suppliers in the United States. This hanger model is widely used and readily available in the United States. At least two manufacturers use this same model number for a joist hanger with a similar (but not identical) design and allowable capacity. The hanger model is considered to be heavier and more expensive than the lightest hangers that are commonly used. This hanger would normally be selected for a heavier required capacity, but it is not the heaviest used in this size category.



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

6

The joist hanger is made from 16 gauge galvanized steel. The measured steel thickness was 1.40mm (0.055 in.). The hanger is designed to fit a 2x6 joist but can also be used for a larger joist. This hanger is also commonly used to connect a roof truss to a girder truss. Since the bottom chord of many common trusses are 2x4 and the bottom chord of most girder trusses are 2x6 or 2x8, this size fits well with many roof trusses.

For the maximum capacity, this joist hanger model uses fourteen 89x4.12 mm (3.5x 0.162 in.) 16d common nails connecting directly from the hanger into the supporting beam. An additional six 16d common slant nails are installed into the joist at or near a 45 degree angle. These slant nails are in double shear. They penetrate the end of the joist and into the header at the slant angle.

The nails used were sold and labeled as 16d common nails and appeared to be typical of framing nails. They were measured at 89 mm (3.5 in.) long (from bottom of head to tip). The measured diameters varied from 4.01 to 4.17 mm (0.158 to 0.164 in.). The nail surface was smooth and bright. The nail shafts had eight slight, transverse indentations on each side in an area from 5 to 15 mm (0.2 to 0.6 in.) from the nail head. The head diameters were 9.1mm (0.36 in.) and the head thickness was 1.6 mm (0.062 in.).

The lumber was similar to, but somewhat more consistent than, lumber that is often used in actual construction. The lumber was purchased as #2 and better Douglas Fir. The beam (or header) members were 4x6 and the joist member were 2x6. The pieces were selected to avoid major lumber characteristics in the hanger area that may weaken the connection. Some more common characteristics such as small knots, small drying checks, and minor slope of grain were present. The lumber was graded as surface green, and all lumber was air-dried at room temperature, until the measured moisture content was between 11 and 15%. Care was taken to avoid drying below 11%.

All materials were accurately cut. All nails were driven by hand using a 0.57 kg (20 ounce) hammer. To provide consistent nailing, a pilot hole was drilled for all nails. The depth of the pilot hole was near one-third the nail length. The pilot holes were drilled with a 2.38 mm (3/32 in.) inch bit, which is 59% of the nail diameter. The 2005 National Design Specification for Wood Construction (2005 NDS) allows pilot holes up to 75% of nail diameter without capacity reduction.

TESTING METHODS

Except as noted herein all procedures specified in ASTM D 7147-05 were followed. A 305 mm (12 in.) long steel load transfer block was used to distribute load along the top of the joist and avoid excess crushing. All assemblies were preloaded to 4.45 kN



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

7

(1000 lbf) before testing. The movement rate of the crossheads was from 3.8 to 5.1 mm (0.15 to 0.20 in.) per minute.

Six assemblies were made using the ASTM D 7147-05 arrangement (Figure 3) with blocking used to restrain the supporting 4x6 beam (or header) members from lateral or rotational movement. 9.5 mm (3/8 in.) metal rods were used as tension reinforcement just inside the blocking. This kept the 4x6 beams tight against the blocks. These assemblies are referred to as the “restrained” assemblies. The blocks were cut 6 mm (0.25 in.) longer than the 2x6 joist, so that a 3 mm (1/8 in.) gap between the joist and the beam at the joist hanger could be maintained. Polyethylene tape was applied to the each end of the joist to minimize load transfer due to friction at the end of the joist. Digital indicators were located at each joist end to measure vertical displacement of the joist with respect to the supporting beam. The measurement was taken from the mid-height of the joist to a point ¼ the beam height from the bottom of the beam.

Figure 3. Restrained test configuration

Six other assemblies were made to allow unrestrained lateral movement and rotation of the supporting beam. These assemblies are referred to as “unrestrained”. The only restraint against lateral movement and rotation is that provided by the joist and joist hanger connection of the joist to the beams. A heavy steel wheel was mounted to each end of the beams. The wheel is mounted to a welded steel bracket to support the 4x6 beam. The axle of each wheel is located at the centroid of the cross-section of



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

8

the 4x6 beam. This arraignment allows free rotation about the centroid and lateral movement. The steel wheel had tapered roller bearings to allow low friction and heavy loads. The steel wheels roll on smooth steel box sections that rested on the bed of the testing machine. The length of the beam was shortened to 267 mm (10.5 in.) to fit the wheels, steel brackets, and steel box sections into the testing machine. This short beam length also avoids significant bending of the beam. See Figure 4. All other aspects including the gaps and polyethylene tape are the same for both types of assemblies.

Figure 4. Unrestrained test set-up

In addition to the measurement of the vertical joist deflection, the unrestrained assemblies had digital indicators to measure the horizontal movement of the beam from the joist at each joist end. The horizontal measurement was taken against the mid height of the beams. A balance protractor was also placed on each beam to take visual measurements (within one degree) of the rotation of the beams.

RESULTS FOR RESTRAINED ASSEMBLIES

The average ultimate load per hanger was 28.7 kN (6449 lbf) for the restrained assemblies as shown in Table 1. The mode of failure for all tested restrained assemblies was wood failure (horizontal shear, splitting and bending) of the joist member that was supported by the hanger. See Figure 5. After the much shear splitting of the joist, the joist ultimately failed in tension stress due to the increase in tensile-bending stress resulting from the lack of full composite action within the joist.



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

9

Due to the wood failure (i.e. horizontal shear), the full capacity of the hanger connection was not achieved.

Figure 5. Before and after horizontal shear failure in joist

In test 4-R an attempt to reinforce the joist within the limits allowed by ASTM D 7147-05 was tried. It was hoped that the reinforcement might prevent the shear failure of the joist. A piece of laminated veneer lumber (LVL) was glued onto each face of the center portion of the joist. See Figure 6. The reinforcement extended to a distance up to 51mm (2 in.) from the end of each hanger, which is the maximum reinforcement allowed by ASTM D 7147-05. The result was still a shear failure in the unreinforced area without a large increase in capacity.

Figure 6. Assembly 4-R with reinforced joist

The average shear stress in the joist at ultimate load for the restrained assemblies can be calculated by beam theory as 8.081 MPa (1172 psi). This compares to an allowable shear stress for Douglas Fir-Larch of 1.24 MPa (180 psi), based on normal duration of load per the 2005 NDS. Based on this comparison it is not surprising that



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

10

the shear stress of the joist limited the ultimate load for the restrained assemblies. A higher ultimate load for the restrained assemblies could be expected, if a larger joist is used and/or a joist material with higher shear capacity is used, such as some engineered lumber products. This may explain why the results of these tests (average 28.7 kN or 6449 lbs) are much lower than the average ultimate value of 44.5 kN (10,000 lbs) reported in the hanger manufacturer’s catalog of 2005.

RESULTS FOR UNRESTRAINED ASSEMBLIES

The average ultimate load per hanger was 8.08 kN (1817 lbf) for the un-restrained assemblies as shown in Table 1. The mode of failure for all tested un-restrained assemblies was due to movement of the hanger and the attached beam away from the end of the joist. This movement was both horizontal and rotational. This movement caused the hanger seat to rotate allowing the joist to slide down the seat and away from the beam.

Table 1. Average ultimate load for unrestrained cases is 28% of restrained cases

Restrained Cases Un-restrained Cases

Max. Load per Hanger Max. Load per Hanger

Test lbf kN Test lbf kN

1-R 6053 26.9 1-U 1520 6.76 2-R 5658 25.2 2-U 2274 10.12 3-R 7236 32.2 3-U 2148 9.55 4-R 6981 31.1 4-U 1353 6.02 5-R 6389 28.4 5-U 2058 9.15 6-R 6377 28.8 6-U 1548 6.89

Average 6449 28.7 Average 1817 8.08

COV 531 2.4 COV 354 1.58

The hanger connection has some moment due to the offset of the seat of the hanger from the center of the supporting beam. When the beam is unrestrained, the only mechanism to resist this moment and prevent rotation is the connection of the beam to the hanger and to the joist. The joist cannot rotate within the plane of the joist, since it is supported at two locations. This moment is resisted by a force couple within the connection. See Figure 7.



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

11

Figure 7. Forces and moment caused by the eccentric load on the hanger

During loading, the top of the beam rotates towards the joist until the small gap between by the beam and the joist closes. After the gap is closed, the upper portion of the beam bears against the joist in compression. The bottom of the beam rotates away from the bottom of the joist, but is restrained by the connection of the beam to the joist hanger and the joist hanger to the joist. This restraint results in a horizontal tension force through the joist hanger connector. See Figure 8.

Figure 8. Mode of failure for the unrestrained case

The ultimate mode of failure is due to the nails from the joist hanger into the joist shearing through wood near the end of the joist. This shearing is parallel to the grain of the joist and very close to the joist end. See Figure 9. It is well known that nail connection into wood are weak in this mode of failure. Wood fasteners require reasonable end distances for this type of loading to achieve the design value of the fasteners.



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

12

Figure 9. Failure of unrestrained case by nails splitting out of the end of the joist

COMPARE RESULTS: RESTRAINED AND UNRESTRAINED ASSEMBLES

The average ultimate load per hanger was 28.7 kN (6449 lbf) for the restrained assemblies and 8.08 kN (1817 lbf) for the unrestrained assemblies. This difference is clearly statistically significant. This confirms the hypothesis that the downward load capacity of the joist hanger is significantly less when no additional restraints are provided to the connection. The average ultimate load for the unrestrained assemblies was 28 percent of the average ultimate load for the restrained assemblies.

The average ultimate load per hanger for the unrestrained assemblies (8.08 kN or 1817 lbf) was less than the design value for the hanger of 11.4 kN (2565 lbf), based on normal duration of load. Since the test is a short term load the difference is larger, if we compare it to a design value of 14.8 kN (3335 lbs) for a short term loading such as wind.

DISCUSSION

A scaled comparison of the testing results to the design values and the manufacturer stated average ultimate load is shown graphically in Figure 10. These results are



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

13

concerning because they shows that the ultimate strength for the unrestrained case is lower than the design values that are commonly used.

Figure 10. Scaled comparison of load values for hanger connection

It is not clear, as discussed earlier, how much lateral and rotation restraint is provided by actual construction. It is likely that the degree of constraint varies widely based on the type of connection, the related framing, and finish materials in the vicinity of the connection. Wood-to-wood connections within roof truss systems may often have less restraint than connections in floor systems.

It is likely that almost all common construction provides some level of support constraint. The unrestrained case tested is an extreme case with no support constraint. This should be considered as an extreme lower limit of what is possible.

Due to the wide variety of models of hangers it would be a mistake to assume that all hanger models will have such a large reduction in capacity without support restraints. The identified mode of failure should be very different with face-mount hangers. Hanger size may be a factor, since the length of the moment arm in the unrestrained mode of failure decreases with shorter hangers. The use of slant nailing in the connection from the hanger to the joist may weaken the connection in the unrestrained mode of failure.

The testing uncovered a mode of failure that can occur in real construction but cannot occur in the ASTM D 7147-05 testing standard. This may indicate that some changes are needed in the testing standard. Possibly an unrestrained test could be incorporated with a lower safety factor to prevent this mode of failure.

CONCLUSION

The capacity of a wood-to-wood joist hanger connection is greatly reduced if there is no lateral and rotational constraint on the supporting beam, for the model of joist hanger tested. If the supporting beam is not restrained, the mode of failure is different than what occurs by the standard testing method of ASTM D 7147-05.



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

14

The ASTM D 7147-05 testing standard allows the usage of constraints on the supporting beam. If the supporting beam is not constrained by other building elements, this may result in an over estimation of the capacity of some connections. Building designers should be aware of this so that the supporting beam is braced to provide the needed lateral and rotational resistance. Further research is needed to determine methods to provide this lateral and rotational resistance.

REFERENCES

American Forest & Paper Association, Inc., AF&PA American Wood Council. (2005). National Design Specification (NDS) for Wood Construction 2005 Edition. Washington, DC

ASTM International. (2005). ASTM D 7147-05 Standard Specification for Testing and Establishing Allowable Loads of Joist Hangers. West Conshohocken, PA.

ICC Evaluation Service, Inc. (2008). Acceptance Criteria for Joist Hangers and Similar Devices AC13. Whittier, CA.

ICC Evaluation Service, Inc. (2008). ESR-2549: Simpson Strong-Tie Face-Mount Hangers for Wood Framing. Whittier, CA.

ICC Evaluation Service, Inc. (2009). ESR-1881: USP Structural Connectors. Whittier, CA.

International Code Council, Inc. (2009). 2009 International Building Code. Country Club Hills, IL.

Simpson Strong-Tie Inc. (2005). Wood Construction Connectors C-2005. Pleasanton, CA.

Simpson Strong-Tie Inc. (2009). Wood Construction Connectors 2009-2010 C-2009. Pleasanton, CA.

USP Structural Connectors. (2007). Full Line Product Catalog (54th ed.). Burnsville, MN.



Dow

nloa

ded

from

asc

elib

rary

.org

by

Mon

ash

Uni

vers

ity o

n 09

/28/

13. C

opyr

ight

ASC

E. F

or p

erso

nal u

se o

nly;

all

righ

ts r

eser

ved.

[American Society of Civil Engineers Structures Congress 2011 - Las Vegas, Nevada, United States...

Documents

Transcript of [American Society of Civil Engineers Structures Congress 2011 - Las Vegas, Nevada, United States...