US3512404A

US3512404A - Truss testing method and apparatus

Info

Publication number: US3512404A
Application number: US751244A
Authority: US
Inventors: John Calvin Jureit
Original assignee: Automated Building Components Inc
Current assignee: Gang Nail Systems Inc
Priority date: 1968-08-08
Filing date: 1968-08-08
Publication date: 1970-05-19
Anticipated expiration: 1987-05-19

Description

May 19, 1970 J. c. JUREIT TRUSS TESTING METHOD AND APPARATUS 2 Sheets-Sheet 1 Filed Aug. 8, 1968 cc D com INVENTOR- JOHN CALVIN mm BY $311M M TE 1: a a 3 3 A: m w. h 5 3 E m a a 25 2 k: A. Ti 7/ ii 3 E n 5 y 8 0: m2 vm vm S 5 NO 2% ATTORNEYS May 19, 1970 J. c. JUREIT 3,512,404

TRUSS TESTING METHOD AND APPARATUS Filed Aug. 8. 1968 2 Sheet-Sheet 2 United States Patent 3 512,404 TRUSS TESTING MllTl-IOD AND APPARATUS John Calvin Jureit, Coral Gables, Fla., assignor to Automated Building Components, Inc., Miami, Fla., a corporation of Florida Filed Aug. 8, 1968, Ser. No. 751,244 Int. Cl. G01n 3/08 U.S. C]. 73-88 13 Claims ABSTRACT OF THE DISCLOSURE The present invention includes a jig carrying wooden structural elements clamped in position to form a truss. Connector plates are applied at the joints thereof as by a press. After unclamping the compl ted truss and While retaining it on the jig, a fluid operated piston and cylinder applies a force at the peak of the truss as well as at the panel points (except at heels) toward the lower chord members. Reaction plates butt the heel portions of the lower chord to prevent lateral movement of the truss. Gauges proportional to the strain are located at opposite ends of the truss and gauges measuring truss deflection are located below the truss peak, the central portion of the lower chord and the panel joints along the lower chord. Strain and deflection can be measured and correlated with the applied load to determine if the structural elements are capable of withstanding their designed loads. Indicia are provided on the jig to measure the recovery of the truss to its original configuration after the test load is removed to provide a measure of overall truss integrity and elasticity.

The present invention relates to an apparatus and method for pretesting load bearing structural members and particularly to an apparatus and method for loading wooden trusses before use and determining the capability of the trusses and their structural elements to withstand their designed loading.

In recent years, the building trades have shown a marked trend toward prefabrication, particularly in the construction of relatively low cost housing. Various frame portions of such houses have been preassem'bled, the most common prefabricated element probably being the roof truss. This prefabrication itself has undergone an evolution from hand nailing and bolting of structural elements forming the roof truss to the vastly improved method of construction made possible by the advent of structural butt joints formed with unitary connector plates of the type described in U.S. Pat. No. 2,877,520 issued Mar. 17, 1959.

In a large proportion of all presently constructed roof trusses, the lumber or structural elements forming the parts of the truss are precut and assembled on a jig or frame which clamps the lumber or el ments in position for the application of connector plates at the butt joints. The connector plates, preferably of the foregoing type, are usually applied on opposite sides of the butt joints and embedded into such elements by a pressing operation. In one method, the jig comprises a jig table which carries the truss along a conveyor below a press, the press being actuated as each joint passes thereunder to embed the associated plates. This method is illustrat d in U.S. Pat. No. 3,238,867 of common assignee herewith. Other types of truss fabricating systems employ a portable press which is movable about the jig assembly and applied at each joint of the pre-assembled truss to embed the connector plates. Still others provide a plurality of movable presses disposed at locations generally corresponding to the joint locations and, when located, stamp the connector plates into the joints.

3,512,404 Patented May 19, 1970 ICC With the formation of prefabricated trusses being automated to this extent, there has arisen the need to test the trusses before installation and use to determine whether or not the prefabricated truss as a whole and the lumber elements forming the truss in particular can withstand the designed loading. It sometimes occurs that the truss joints are improperly formed and/or that irregularities in the particular truss elements, such as knots, improper seasoning and the like, are present, all of which would affect the strength, elasticity, and integrity of the truss and the defective truss elements to the extent that the truss or one or more of its elements cannot carry the designed loading. Pretesting or preloading the truss before installation and the use to insure the integrity, effectiveness, and capability of the truss as a whole and the truss members individually, i.e., to insure that the joints are properly formed and that the working stresses in the truss elements are well below the fracture stresses, is not generally practical in the building industry, sometimes resulting in defective trusses. Where trusses are pretested, it has proved time consuming and expensive, and, in general, there is no really effective and eificient mechanism available prior to the present invention for preloading and testing the truss before use. In the single known previous method of pretesting the truss, selected trusses are usually positioned upright and supported at their heel portions as in use and loaded, for example, with heavy cinder block, to a predetermined load in the range of their working stresses or designed loads to determine if fracture occurs. This has proven generally unsatisfactory as each truss cannot be economically tested in this manner or all the pieces generally cannot be recovered if fracture of one or more of the pieces occurs, whereby a considerable quantity of lumber would be wasted.

In accordance with the present invention, each truss can be conveniently tested to determine overall truss integrity and to determine the existence of and locate defects in the various structural elements forming the truss. This can be accomplished without loading the truss to its designed load and without removing the truss from the.

jig. To this end, the present invention provides a jig assembly on which the lumber pieces forming the truss are assembled in the truss pattern with the connector plates disposed on opposite sides of the joints. The plates are embedded into the truss by any one of the methods described previously. Transverse reaction pads are provided on the jig assembly against which heel portions of the base chord butt. Fluid actuated cylinders are carried by the jig assembly and apply a predetermined loading to the panel joints along the top chords of the truss (heel joints excepted) in the direction of the lower truss chord thereby providing loadings equivalent to the loadings encountered under actual loading conditions.

By locating an extensometer at both ends of the truss, the axial elongation or total strain on the lower chord member can be measured. By calculating the strain from theoretical and/or empirical considerations on a lower chord member of known length and type of wood for a predetermined applied loading on a specified truss, it can be seen that the measured total strain on the lower chord member for lumber substantially free of defects should lie close to the calculated strain or at least within a predetermined range of acceptable strain values for the applied loading. Thus, a measured strain value above both the theoretical or empirically calculated strain value and beyond the acceptable range of strain values for the given loading, type of lumber and truss, and length of chord, indicates an unacceptable elongation of the lower chord member. The area of the lower chord in which the excessive elongation occurs, such as, for example, at a knot, can most often be located visually. The lower chord can then be reinforced 'by applying one or more reinforcing plates of the type employed in forming the truss joints in the area of the defect in a manner as set forth in my copending application Ser. No. 282,300, filed May 22, 1963. In this manner, the otherwise defective truss can be saved and reinforced to carry its designed loading without tearing the truss down or wasting lumber by rejecting the defective piece.

A measured strain value less than the calculated strain value or below the acceptable range of strain values may indicate that the lower chord member is not being subjected to the designed tensile loading. This may be caused by an unacceptable compression of one or both of the upper chord members or unusual compression strength exhibited by one or more of the truss web members. Here again, the defect can most often be located visually and, when located, can be corrected by applying one or more connector plates in the area of the defect. Again, the truss elements are not fractured and, instead of rejecting the entire truss, the truss can be reinforced at its defective areas and utilized similarly as other non-defective trusses.

Further to the present invention, displacement measuring devices are disposed to measure the deflections of the panel joints at the apex of the truss and along the upper truss chords (heel joints excepted) when the truss is subjected to the applied loading as before. The deflection of these upper panel joints is proportional to the strain in both upper chord members and the magnitude of such deflection for a given truss can be calculated from theoretical and/or empirical considerations. Accordingly, for a given truss subjected to a predetermined applied loading in the manner as set forth previously, measured deflections of these upper panel joints above the calculated deflections or beyond an acceptable range of deflections for each such joint indicates unacceptable compression of the upper chords or the intermediate web members. Again, the defective area can usually be visually located and reinforced as before.

Other deflection measuring gauges are disposed medially between the ends of the bottom chord member and at the lower panel joints (heel joints excepted) to measure the bow or deflection of the truss under the applied loading. Again, theoretical and/or empirical considerations can provide calculated or expected deflections for a given truss subjected to a predetermined loading. By a correlation of the readings on the strain and deflection gauges, the defective member can be readily located, i.e., it can be determined that either the bottom chord member, the upper chord members,-or the intermediate web members are defective. For example, if one of the upper chord members is defective, and compresses to a larger extent than expected or calculated under the applied load ing, the measured strain at the ends of the lower chord members will be less than the calculated strain or below the acceptable range of strain values for such loading, and the measured deflection at the panel joints along the upper chords and along the lower chord member will be greater than their calculated deflection or the corresponding acceptable range of deflections. Conversely, if one or more of the web members are defective in compression, the measured strain at the ends of the truss will be higher than the calculated strain or above the acceptable range of strain values and the measured deflection of the lower chord member will be less than its calculated deflection or below the acceptable range of strain values for such applied loading. Once the defective member is located, it can either be replacedor readily reinforced as by the application of additional plates of the foregoing discussed type.

Further to the invention, the amount of recovery of the truss to its original configuration after the test load is removed provides an excellent measure of the overall integrity and elasticity of the truss. This can be readily determined by recording and comparing the deflection readings on the gauges before the test load is applied and after it is removed.

Accordingly, it is a primary object of the present invention to provide a method and apparatus for preloading prefabricated trusses and the like before installation and use.

It is another object of the present invention to provide an apparatus and method for testing prefabricated trusses and the like which is readily and conveniently accomplished while the trusses are assembled on their jig tables.

It is still another object of the present invention to provide an apparatus and method for testing prefabricated trusses wherein a defective truss member can be readily identified.

It is a further object of the present invention to provide an apparatus and method for testing prefabricated trusses wherein the trusses need not be loaded to their designed load in order to determine the effectiveness of the truss and the truss members.

It is a related object of the present invention to provide an apparatus for testing prefabricated trusses, including a fluid actuated cylinder carried by the jig assembly for applying a predetermined load to the truss while the truss is on the jig assembly in a manner similar to actual loading conditions, together with strain and deflection measuring gauges carried by the jig assembly for measuring the lateral strain on and load induced deflections of the truss.

It is still a further object of the present invention to provide an apparatus and method for testing prefabricated trusses whereby a measure of the overall elasticity and integrity of the truss can be obtained.

It is still a further object of the present invention to provide an apparatus and method for testing prefabricated trusses having the foregoing characteristics wherein the load applying mechanism and the strain and deflection measuring gauges are movably carried by the jig assembly whereby the manufacture and testing of a large variety of different sizes and shapes of wooden structures on the same jig without major modifications of the jig itself can be accomplished.

These and further objects and advantages of the present invention will become more apparent upon reference to the following specification and claims and the appended drawings wherein:

FIG. 1 is a fragmentary plan view of a combination jig and prestress testing assembly constructed in accordance with the present invention and showing a portion of a completed truss subjected to an applied loading;

FIG. 2 is a fragmentary sectional view taken about on line 22 of FIG. 1 showing a truss clamping device and deflection measuring gauge;

FIG. 3 is a cross sectional view taken about on line 33 of FIG. 1;

FIG. 4 is an enlarged fragmentary plan view of the base reaction pad; and

FIG. 5 is a fragmentary vertical cross sectional view taken about on line 5--5 of FIG. 1.

.DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1 of the drawings, there is shown a jig assembly, generally indicated at 10, comprising a jig pad or pallet 12 formed of a large heavy sheet of metal or of a thin sheet of metal suitably reinforced or of any other suitable structural material upon which the elements of the jig may be mounted. For purposes of clarity, only the center and lefthand portions of the complete jig assembly are shown. It will be understood, however, that the complete assembly consists of a righthand portion which is constructed substantially as a mirror image of the lefthand portion.

Mounted at the center of jig pad 12 and extending transversely and vertically thereacross is a stationary vertical peak guide bar 14 which carries a combination peak reaction and load applying pad 16 slidably mounted for movement thereon. Extending perpendicular to the peak guide 14 along the entire length of the jig pad 12 is a guide bar 18 which slidably mounts a heel reaction pad 20, a one-third point reaction pad 22, and a splice reaction pad 24. Guide bars 14 and 18 are identical in construction, stationary, and are illustrated in FIG. 2, which represents a cross section through the lower guide bar 18.'It will be seen that guide bar 18 consists of an elongated metal strip having flanges 26 which give the strip a generally T-shaped cross section. Guide bar 18 is secured to the jig pad 12 in any suitable manner, such as by bolting, welding, or riveting.

The splice reaction pad 24 consists of a metal plate 28 suitably secured on top of the backing plate 30. Splice reaction pad 24 is slidably secured to guide bar 18- by a pair of metal strips 32 having flanges 34 which matingly engage the flanges 26 on guide bar 18. Strips 32 are secured to pad 24 in any suitable manner, preferably by screws passing from the upper surface of plate 28 into strips 32 so that the screw heads are readily accessible and the screws may be tightened or loosened to respectively lock or permit sliding motion of the reaction pad relative to guide bar 18. A tape 36 runs along the centerline of guide bar 18 bearing suitable indicia and a slot, not shown, is formed through reaction pad 24 directly above tape 36 such that pad 24 may be accurately located at any predetermined position along bar 18. The heel and one third

point reaction pads

20 and 22, respectively, are similarly constructed with respect to their mounting on jig table 12.

Referring to FIGS. 2 and 4, an angle member 40 having a base 42 and a pair of upstanding flanges 44 is slidably mounted on splice reaction pad plate 28 by means of a pair of upstanding bolts 46 which project through L- shaped slots 48 formed in the base 42 of angle member 40 and threaded into tapped openings formed in plate 28. In this manner, member 40 can be moved by longitudinal and transverse movement thereof between two positions, a first position wherein flanges 44 butt the outer edge of the lower chord member LC. of a truss and a second position wherein flanges 44 are spaced from the lower chord for reasons as will become apparent. The onethird reaction pad 22 is similarly constructed as the splice reaction pad and its angle member 49 also has a pair of spaced upstanding flanges 50. Heel reaction pad 20 mounts an angled bracket 52 by means of screws, not shown, whereby bracket 52 is stationary relative to pad 20.

Referring to FIG. 1, 2, and 4, the locking devices 54 each comprises a cylindrical barrel 56 having base plates 58 suitably secured to the plates 28 of the associated pads. Slidably mounted in barrel '56 is a plunger consisting of a tube 60 having an arcuate plate 62 secured on its end. A plunger block 64 is slidably mounted in the other end of barrel 56 and receives a locking plunger 66 within a bore 68, the plunger 66 being biased upwardly against barrel 56 by a spring 70. An aperture 72 is formed in the upper surface of barrel 56 to the right of the plunger position in FIG. 2. A leaf spring 74 is secured to the upper side of barrel 56 at 76 and has a dimple 78 at one end overlying aperture 72.

A pair of arms 80 project from the left end of barrel 56 in FIG. 2 and mount a pivot pin 82. Pin 82 rotatably supports an eccentrically mounted circular cam 84 having an actuating handle 86 projecting from its periphery. A spring 88 is mounted within tube 60 and simultaneously urges tube 60 to the right in FIG. 2 and block 64 to the left into engagement against cam 84.

It will be seen that with cam 84 in the position shown in FIGS. 2 and 4, block 64 butts cam 84. If cam 84 is rotated, block 64 moves to the right applying pressure to tube 60 by spring 88. When plunger 66 is aligned with aperture 72, the plunger is biased into aperture 72 thereby locking the block 64 in an advanced position. Cam 84 may then be returned to an unlocked position with plunger 66 retaining block 64 in the advanced position. With block 64 in the advanced position, it will be noted that depression of leaf spring 74 causes dimple 78 to depress locking 6 plunger 66 from without aperture 72 whereby block 64 is retracted under the bias of spring 88 to the position illustrated in FIG. 2

Referring to FIG. 1, a pair of parallel stationary guide bars 90 are disposed near the center and left end of jig pad 12 respectively and provide an adjustable mounting for a horizontal one-fourth point movable guide bar 92. The left end of guide bar 92 is attached to a connector plate 94 by a pin 96 received in a slot 98 in the connector plate. The connector plate per se is slidably secured to the left guide bar 90 by flanged strips of the same type illustrated in connection with splice reaction paid 24. A slot 100 is provided in connector plate 94 to view a tape 102 carried by guide bar 90. The right end of guide bar 92 is pivotally secured to a second connector plate 104 by a pin 106. Connector plate 104 is slidably mounted on the central guide bar 90 in the same manner as plate 94 and is also provided with a slot, not shown, for positioning plate 104 along bar 90.

A one-fourth point reaction pad 108 is slidably mounted on movable bar 92 in a like manner as the spice reaction pad is mounted to the guide bar 18. The one-fourth point reaction pad 108 carries a lumber positioning pin 110 and a locking device 54 similar to the locking device on the spice reaction pad. The one-third point reaction pad 22 carries no cam but has a lumber positioning pin 112 removably mounted thereon.

The heel reaction pad 20 is also provided with a locking device 54 while the peak reaction pad 16 is provided with a pair of locking devices 54 on opposite sides of the peak splice. Lumber positioning pins 114 are also removably mounted on pad 16.

A centrally located support bracket is slidably mounted adjacent the upper edge of pad 12 along peak guide bar 14 and carries a fluid operated piston and cylinder 122, the bracket being secured to bar 14 in selected adjusted position therealong by screws, not shown. The piston rod 123 thereof carries a V-shaped head 124 engageable against the apex of the truss formed by the butting upper chord members U.C. The reaction pad 108 also carries a fluid actuated piston and cylinder 122a and the piston rod 123a thereof pivotally carries a head 124a engageable against the upper chord U.C. at the quarter panel joint. Piston heads, 124, 124a are thus extendable to apply loads to the truss in a manner equivalent to actual loading conditions. A suitable fluid pressure source, not shown, is provided piston and cylinders 122, 122a via conduits 125, 125a.

In order to measure the longitudinal displacement of the ends of the truss under the applied loading provided by cylinders 122, 122a and the deflection of the truss at its panel joints (heel joints excepted), extensometers or displacement measuring gauges are disposed on the heel, one quarter point, one third point, and splice

reaction pads

20, 108, 22, and 24, respectively, and on pallet 12, the latter being in position to measure the displacement of the truss peak. Referring now to FIGS. 1 and 3, a displacement measuring gauge 126 is slidably mounted on each heel reaction pad 20 in a key slot 128 extending parallel to guide bar 18. Gauge 126 is carried by a bolt 130 having an enlarged head 131 which is received in key slot 128. A nut 132 having a handle 133 secured thereto is threaded on bolt 130 and clamps gauge 126 in selected adjusted position along slot 128. Gauge 126 may be of any type of suitable displacement measuring device, such as, for example, a dial gauge operable in response to the displacement of a plunger 134. Other types of mechanical micrometer type gauges or electrically responsive gauges, such as potentimeters, strain gauges, and the like could be employed.

Similar type gauges 135 for measuring the deflection of lower chord member LC. medially of the length of the truss and at the one third panel joint, are fixed to splice reaction pad 24 and one third reaction pad 22, respectively, by screws, not shown. Gauges 135 have extended plunger arms 137 which overlie the bases of the associated angle members 40 with the heads 139 of the arms extending between the spaced upright flanges for abutment against lower chord member L.C. A like gauge 135a for measuring the deflection at the one quarter joint panel is fixed to reaction pad 108 and its plunger arm 137a extends such that head 139a bears against the joint members. A similar type gauge 140 for measuring the deflection of the truss peak is slidably mounted along peak guide bar 14 between peak and

heel reaction pads

16 and 24, respectively, by a bracket 142. Gauge 140 is secured in selected adjusted position along bar 14 by screws 143 which thread through bracket 142 to clamp the flanges 26 on bar 14 between screws 143 and inwardly directed flanges, not shown, carried on the underside of bracket 142. In this manner, when peak reaction pad 16 is located in a predetermined position along guide bar 14 in accordance with the size of the truss being fabricated, gauge 140 can likewise be adjustably positioned along bar 14 such that the head 1 44 on its plunger member 145 can engage the peak ends of the upper chord members of the truss, or, in this instance, the butted ends of web members W.

To employ the jig and prestress testing assembly, a series of connector plates P of the foregoing type disclosed in US. Pat. No. 2,877,520 are spotted on the reaction pads with the teeth thereof extending upwardly prior to setting the wooden members on the reaction pads. The wooden members are then disposed on top of the teeth of the plates and a second set of connector plates is then laid on top of the wooden members with the teeth directed downwardly so that a single pressing operation is effective to completely form each joint of the roof truss.

With the desired dimensions of the truss known, the various reaction pads are properly positioned along their associated guide bars according to previous data by aligning the respective reaction pads with the appropriate indicia along their underlying tapes. The reaction pads are secured in place on their respective guide bars by tightening their various locking screws and the various chord and web members forming the truss are then placed on the jig over the plates and secured in position by locking the various locking devices as by moving the handles thereof to advance arcuate plates 62 to bear against the appropriate members of the truss. The locking devices clamp the members of the truss in place and the handles may be returned to their previous position as locking plunger 66 precludes retraction of plunger block 64. It will be noted that the

angle members

40 and 49 are moved toward and to a position butting the outer edge of lower chord member LC. The truss is now jigged and ready for pressing and may be placed between the platens 148 of any suitable press which, when actuated, descends to press the teeth of the plates into the wooden members to form the desired butt joints. At the end of the press stroke, the upper platen flexes leaf spring 74 depressing dimple 78 to move locking plunger 66 out of aperture 72, thereby releasing plunger block 64. It will be noted that at this point in the fabrication operation, the truss is completely assembled and could be removed without testing.

To preload and test the truss while lying on the jig assembly, the luumber positioning pins 110 and 114 are removed and the

angle members

40 and 49 are moved longitudinally and then transversely to space the respective flanges thereof from the outer edge of the lower chord member L.C. Note that the heel angle brackets 52 remain fixed to the heel reaction pads and provide end supports for the truss when test loaded in the following manner similarly as the truss would be subjected to loading in use. The gauge readings are then recorded.

To prestress the truss, a predetermined loading, for which predetermined data providing the strains and deflections at the various measuring points for such loading has been calculated and which lies well below the design loading, is applied by actuating the piston and cylinder arrangements 122, 122a. Piston heads 124, 124a, respectively, engage the peak joint and the one third joint of the truss, thereby loading the truss against the heel reaction bracket 52 with a loading equivalent to the actual loading in use. If the truss and its structural members are effective to carry their design loadings, the measured values as displayed on

gauges

126, 135, a and will approximate the calculated strain or deflection or at least lie within acceptable predetermined strain or deflection limits. However, if there is a defective truss joint or a defect in one or more of the structural members forming the truss, the measured strain or deflections will vary significantly from the calculated range of strains or deflections. By correlation of the measured strains and deflections of the various gauges and noting the variations thereof from the calculated strains or deflections, it is possible to determine the location of the defect.

For example, a strain reading on the heel gauge 126 greater than the calculated or acceptable range of strains indicates an elongation of the lower chord member to larger extent than would be anticipated. Accordingly, a workman may locate the defect and apply a connector late to reinforce the defective portion of the lower chord member in a manner as disclosed in copending application Ser. No. 282,300, filed May 22, 1963. A larger deflection measurement than calculated on either the splice or peak gauges would indicate that either the upper chord member or web member is weak in compression and a workman may likewise locate the defective portion of such members and similarly apply a reinforcing plate. A deflection measurement at the truss peak higher than the calculated or accepted range of deflections coupled with a deflection measurement at the splice pad lower than the calculated or accepted range of deflections would indicate that the web member is defective in compression and this too would be remedied in identical fashion.

A large deflection measurement than calculated at the one third or one quarter joints would indicate that a web member is weak in compression and this may be remedied in similar fashion.

The piston heads 124, 124a are then retracted permitting the truss to return to its original configuration. The finished truss may then be lifted from the jig, The gauge readings are again recorded and the difference in these jreadings and the original gauge readings prior to the test provide a measure of the overall integrity and elasticity of the truss.

It will be noted that only a few further steps are required to preload and test the truss while the same lies on the jig and these steps can be accomplished in a .minimum amount of time. Note also the location adjustability of the piston and cylinder arrangements 122, 122a, the heel splice, peak and intermediate reaction pads, the gauge 140 along bar 14 and gauges 126 along the heel reaction pads. In this manner, various sizes and shapes of trusses can be assembled, prestressed and tested.

What is claimed and desired to be secured by US. Letters Patent is:

1. An assembling and testing apparatus for structural wooden trusses and the like having their members jointed together by connector plates of the type having teeth struck therefrom for embedment into the members, said apparatus comprising support means for the structural truss, means carried by said support means for holding the wooden members in predetermined positions to form the truss, press means adjacent said support means for embedding the teeth of the connector plates into the joints formed by the prepositioned members, means for applying it load to the completed truss, abutment means carried by said truss support means and providing a reaction fon :e for preventing the truss from being displaced from the support means under the applied loading, and at least one measuring gauge disposed in measuring position relative to the completed truss for determining a load bearing characteristic of the completed truss under the applied loading, said measuring gauge being carried by said support means adjacent the heel portion of the truss in position to measure the elongation of the lower chord member of the truss under the applied loading.

2. An assembling and testing apparatus for structural wooden trusses and the like having their members jointed together by connector plates of the type having teeth struck therefrom for embedment into the members, said apparatus comprising support means for the structural truss, means carried by said support means for holding the wooden members in predetermined positions to form the truss, press means adjacent said support means for embedding the teeth of the connector plates into the joints formed by the prepositioned members, means for applying a load to the completed truss, abutment means carried by said truss support means and providing a reaction force for preventing the truss from being displaced from the support means under the applied loading, and at least one measuring gauge disposed in measuring position relative to the completed truss under the applied loading, said measuring gauge being carried by said support means adjacent the lower chord member of the truss in position to measure the deflection of the truss under the applied loading.

3. An assembling and testing apparatus for structural Wooden trusses and the like having their members jointed together by connector plates of the type having teeth struck therefrom for embodiment into the members, said apparatus comprising support means for the structural truss, means carried by said support means for holding the wooden members in predeetermined positions to form the truss, press means adjacent said support means for embedding the teeth of the connector places into the joints formed by the prepositioned members, means for applying a load to the completed truss, abutment means carried by said truss support means and providing a reaction force for preventing the truss from being displaced from the support means under the applied loading, and at least one measuring gauge disposed in measuring position relative to the completed truss for determining a load bearing characteristic of the completed truss under the applied loading, said measuring gauge being carried by said support means adjacent the upper chord members of the truss in position to measure the deflection of the upper chord member under the applied loading.

4. An assembling and testing apparatus for wooden trusses and the like having their members joined together by connector plates of the type having teeth struck therefrom for embedment into the members, said apparatus comprising support means for the truss, means carried by said support means for holding the wooden members in predetermined positions to form the truss, press means adjacent said support means for embedding the teeth of the connector plates into the joints formed by the pre positioned members, means for applying a load to the completed truss, abutment means carried by said truss support means and providing a reaction force for preventing the truss from being displaced from the support means under the applied loading, and at least one measuring gauge disposed in measuring position relative to the completed truss for determining a load bearing characteristic of the completed truss under the applied loading, said support means including a plurality of pads for supporting the truss at the joints thereof, said pads being mounted for movement along predetermined paths between a plurality of truss supporting positions to accommodate trusses of various sizes, said gauge being carried by one of said pads whereby the gauge is located in measuring position relative to a completed truss of any one of the various sizes thereof.

5. Apparatus according to claim 4 wherein said load applying means includes a fluid operated piston and cylinder carried by said support means.

6. Apparatus according to claim 4 including at least two measuring gauges, one of said gauges being carried by said support means in position to measure the strain on the lower chord member of the truss under the applied loading and the other of said gauges being carried by said support means in position to measure the deflection of the truss under the applied loading.

7. An assembling and testing apparatus for wooden trusses and the like having their members joined together by connector plates of the type having teeth struck therefrom for embedment into the members, said apparatus comprising support means for the truss, means carried by said support means for holding the wooden members in predetermined positions to form the truss, press means adjacent said support means for embedding the teeth of the connector plate into the joints formed by the prepositioned member's, means for applying a load to the completed truss, abutment means carried by said truss support means and providing a reaction force for preventing the truss from being displaced from the support means under the applied loading, and at least one measuring gauge disposed in measuring position relative to the completed truss for determining a load bearing characteristic of the completed truss under the applied loading, said support means including an elongated jig table, a plurality of pads for supporting the truss at the joints thereof, said pads being mounted on said jig table for movement along predetermined paths between a plurality of truss supporting positions for accommodating trusses of various sizes, one of said paths being mounted for substantially transverse movement across said jig table for supporting an upper joint member of the truss, two of said pads being mounted for substantially longitudinal movement along said jig table for supporting heel jointed members of the truss, said load applying means including a piston and cylinder carried by said jig table and operable to load the truss in a direction substantially parallel to the direction of movement of said one pad.

8. Apparatus according to claim 7 wherein said abutment means includes an abutment member carried by each of said heel reaction pads.

9. A method of assembling Wooden members to form a truss and testing the completed truss before use, comprising the steps of: locating the structural members in predetermined positions on a jig assembly to form a truss pattern and thereby forming a plurality of joints between said members, disposing connector plates of the type having teeth struck therefrom adjacent at least one side of the joints of the members, embedding the teeth of the connector plates into the joints to form a rigidized truss, applying a load to the rigid truss While the assembled truss is located on the jig assembly and measuring a load bearing characteristic of the completed truss while the truss is subjected to the applied loading.

10. A method according to claim 9 wherein the step of measuring includes measuring the endwise elongation of the lower chord member of the completed truss under the applied loading.

:11. A method according to claim '9 wherein the step of measuring includes measuring the deflection of the completed truss under the applied loading.

12. A method according to claim 9 wherein the jig assembly includes pads movably carried thereby for supporting the truss at the joints thereof and including the steps of moving the pads relative to the table to a predetermined position for supporting the structural members of a truss of given size at the joints thereof, and moving a measuring gauge relative to the jig assembly to a measuring position relative to the given truss.

13. A method of assembling Wooden members to form a truss and testing the completed truss before use, comprising the steps of: locating the structural members in predetermined positions on a jig assembly to form a truss 1 1 pattern and thereby forming a plurality of joints between said members, disposing connector plates of the types having teeth struck therefrom adjacent at least one side of the joints of the members, embedding the teeth of the connector plates into the joints to form a rigidized truss, applying a load to the rigid truss while the assembled truss is located on the jig assembly, measuring a load bearing characteristic of the completed tluss While the truss is subjected to the applied loading, including measuring the deflection of the completed truss under the applied loading, removing the load from the truss, and measuring the displacement of the truss from its original configuration after the load has been removed.

References Cited UNITED STATES PATENTS 8/1925 Beggs 7388 5/1928 Reed 7388 10/1936 Harrison 7388 2/1954 Berman 7388 US. Cl. X.R.

331 33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,512 ,40 Dated Mav 19. 1970 JOHN CALVIN JUREIT Invcnt0r(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

I Column 6, line 21, "spice" should read spl ice line 25, "spice" 1 should read splice Column 7, line 64, "luumber" should read lumber Column 9, line 32, "embodiment" should read embedment --l; line 35,

"predeetermined" should read predetermined DEL 7 i am Meat:

Edward M. Fletcher, 1'1.

Attesting Officer