Plug washer

A plug washer useful for holding a vertical stud support member against a masonry wall using studs embedded in the masonry wall at an oblique angle to horizontal, the plug washer having an expanded washer portion which bears against the steel support on one side and a nut on the other, and further having a plug that fits in holes in the support member made to accept the stud, the plug and the washer portion having a hole passing through them at an angle to receive the stud.

FIELD OF THE INVENTION 
This invention is in the field of attaching steel support members to 
structures made of masonry walls. 
BACKGROUND ART 
This invention is a plug washer that is useful for connecting steel support 
members to masonry walls, such as walls made of concrete, brick, cement 
block, stone or the like, all hereinafter referred to as masonry. Although 
masonry walls have great ability to resist compressive loads, they are not 
good at resisting horizontal stresses. Masonry walls are particularly 
vulnerable in regions subject to earthquakes. Older structures in 
earthquake-prone regions or structures damaged by earthquakes should be 
retrofitted to resist earthquakes or provided with a steel support 
structure when being repaired after being damaged in an earthquake. 
To retrofit structures for earthquake resistance it is common to build a 
supporting steel framework adjacent to the masonry walls to prevent 
horizontal stresses from toppling the walls. The supporting steel 
framework is usually built inside the structure and the supporting steel 
must be firmly connected to the masonry walls to hold the support 
structure and the masonry walls together. This is usually accomplished by 
drilling holes in the masonry and in the support steel, embedding studs in 
the holes in the masonry so that they extend through corresponding holes 
in the steel support framework and then connecting the framework to the 
wall with nuts, or the like, to hold the steel framework in supporting 
relationship with the masonry. It has been determined that a stud embedded 
in masonry at an angle oblique to horizontal will have greater strength 
than one embedded to extend horizontally, from the masonry wall. It has 
further been determined that a stud embedded at an angle of 22.5 degrees 
from horizontal provides the strongest connection. 
There are many ways to embed studs in masonry including expansion elements 
of various types placed in holes in the masonry and then expanded by the 
torque of a bolt screwed into the expansion element. A very suitable way 
to embed a stud in a masonry wall is to put epoxy cement in a hole in the 
wall and to insert a stud in the hole so that the epoxy surrounds it. The 
amount of epoxy placed in the hole is such that when it is displaced by 
insertion of the stud it will just fill the hole. The bond between epoxy 
and masonry is stronger than the masonry itself and the bond is also 
stronger than the stud. An epoxy resin can be made viscous enough to flow 
from such a hole very slowly. 
One problem with such a system is that it is difficult to have pre-drilled 
holes in masonry and pre-drilled or punched holes in steel support members 
correspond when they are placed together. A drill bit characteristically 
"walks" from the desired center of the hole when drilling starts so that 
the centers of the holes in masonry and the holes in the steel support 
member do not exactly correspond. In such cases the studs extending from 
the masonry wall cannot pass through the holes in the steel support member 
that were drilled or punched to receive them. When the studs extending 
from a masonry wall do not correspond in position with the pre-prepared 
holes in a steel support member costly and time-consuming revision of the 
holes or the studs must be made to provide adequate support. Another 
problem is that a nut screwed onto a stud that is at an oblique angle from 
horizontal cannot make a flat bearing against a vertical steel support 
element. Tightening a nut that is at an angle to its proposed bearing 
surface will provide unreliable holding force and it will tend to cause 
the stud to bend which reduces the ultimate strength of the stud. 
Although washers are known that accommodate to surfaces that are at an 
oblique angle to a stud, those washers have a central hole that is much 
larger than the diameter of the stud that is to be received in that hole 
because the central hole must accommodate the stud passing through it at 
an angle oblique to horizontal. Even if a washer lies flat against the 
support member, the nut on such a stud cannot bear flatly against the 
washer because of the angle of the stud. The bearing force of a nut 
accordingly is not uniformly distributed on the washers so that the 
holding force of the nut is diminished. Additionally, in studs that are 
held with epoxy or other liquid-phase or plastic cement, some of the 
cement may flow out of the hole in the masonry thereby diminishing the 
strength of the bond. 
DISCLOSURE OF THE INVENTION 
This invention is a plug washer that avoids or greatly mitigates the 
above-mentioned problems. The washer of this invention provides a hole for 
a bolt or stud that is at the same angle to horizontal as the axis of the 
stud, it is only slightly larger in diameter than the stud so that it 
provides a unitary structure that bears flatly against both the nut and 
the support structure. Additionally it prevents cement from flowing from a 
hole in masonry, it provides means to avoid misalignment of the stud and 
its corresponding hole in a support member and it provides that the force 
exerted by a nut screwed onto a stud is uniformly distributed on all 
bearing surfaces and throughout the body of the stud. The plug washer of 
this invention is also easily removable should the structure on which it 
is used is to be revised or demolished. 
The plug washer of this invention is used to hold a vertically oriented 
structure steel piece against a vertically oriented wall by the use of 
studs embedded in the wall at an angle oblique to horizontal, preferably 
an angle of 22.5 degrees. The plug washer of this invention has a washer 
portion and a plug portion. The washer portion has a nut-bearing surface 
and a structure-bearing surface and the two surfaces diverge from one 
another at the oblique angle at which the axis of the studs are set in the 
masonry wall. The plug washer of this invention also has a plug portion 
that extends from the structure-bearing surface. The plug portion is 
preferably cylindrical, it is of smaller diameter than the washer portion 
and it extends with its axis perpendicular to the support-bearing surface 
of the plug washer. 
A common passageway passes through both the washer portion and the plug 
portion. The axis of the passageway is perpendicular to the nut-bearing 
surface of the plug washer. The plug washer of this invention permits a 
structural steel element to be fixed to a masonry wall quickly, it permits 
accurate drilling of holes in masonry, it positions all bearing surfaces 
to be flat against one another and all force on a stud to be exerted 
axially, and it seals the cement in holes in masonry while the cement sets 
.

DETAILED DESCRIPTION OF THE INVENTION 
A plug washer embodying this invention is illustrated in FIG. 1. The plug 
washer is generally designated 10. It consists of a washer element 11 and 
a plug element 12. The washer element 11 includes a steel support-bearing 
surface 13 and a nut-bearing surface 15. The plug portion 12 is preferably 
cylindrical with its axis perpendicular to structural steel-bearing 
surface 13. The surface 16 of plug 12 is simply the end of the plug but it 
is useful for sealing cement in a hole in masonry as will be discussed 
hereafter. 
The plug washer of this invention includes a cylindrical passageway 17. The 
axis of passageway 17 is perpendicular to nut-bearing surface 15. The 
support-bearing surface 13 and the nut-bearing surface 15 diverge at an 
angle of 22.5 degrees in the particular embodiment illustrated but in any 
case they will diverge at the angle that the stud to be described 
hereafter makes with horizontal. 
FIG. 2 illustrates the plug washer of this invention installed to hold a 
steel support element 22 against a masonry wall 20. A stud 24 is inserted 
into a hole 21 which has been drilled into the masonry wall. The hole 21 
is larger in diameter than the stud 24 whereby a space 25 is formed to 
receive epoxy or other suitable cement. To install the steel support 
element 22 against the masonry wall 20 the support element is preferably 
temporarily held tightly against the wall 20 with a pre-punched or 
-drilled hole 23 exposing a portion of the masonry wall. A drill adapted 
to drill a hole at 22.5 degrees from horizontal (in this case) is passed 
through the hole 23 and the hole 21 is drilled with the bit passing 
through the hole 23. By drilling the hole in this way the alignment of the 
hole 21 and the hole 23 is assured. When all of the holes in the masonry 
have been drilled employing this technique, the holes in the concrete can 
be blown free of dust and filled with enough epoxy so that upon 
displacement by insertion of the stud 24 the space 25 around the stud 24 
will be substantially filled with epoxy. Before the studs 24 are inserted 
in the epoxy-filled holes the plug washer is inserted in the hole 23 so 
that the plug virtually fills the hole and the surface 16 is in contact or 
almost in contact with the concrete wall 20. At that point the stud is 
inserted through the hole 17 in the plug washer and into the hole 21 in 
the masonry. When inserted in the hole 21 the stud 24 displaces the epoxy 
so that it virtually fills the hole 21 and completely surrounds the stud 
24. The assembly is then permitted to stand until the epoxy sets whereby 
an extremely strong bond between the stud 24 and the masonry wall 20 is 
formed. When the strong bond is formed the nut 26 is screwed onto the 
threaded end of stud 24 and tightened to provide sufficient holding force 
to cause steel element 22 to reinforce masonry wall 20 and prevent damage 
due to horizontal thrusts. 
It is evident from FIG. 2 that the surface 15 of the washer portion bears 
flatly against nut 26 and that the surface 13 of the washer portion bears 
flatly against the steel support element 22. It is also evident that 
although the stud passes through the plug portion at an angle of 22.5 
degrees, the plug functions only to fill the hole 23 and to position the 
passageway 17 so that it is coaxial with the hole 21. All forces exerted 
by the torque on nut 26 are axial forces with regard to stud 24 and are 
perpendicular forces with regard to nut-bearing surface 15. Any sheer 
force urging plug portion 12 downwardly, as illustrated in FIG. 2, is 
resisted by a perpendicular force against the sides of hole 23 whereby the 
stud 24 is subjected almost entirely to axial tensile stress. 
The plug washer of this invention may be made of any suitable material.