SLOTTED BOLTED CONNECTION ENERGY DISSIPATERS 92

Various types of energy dissipating devices, utilizing friction as means of energy dissipation,
have been tested and studied by researchers [4, 6, 7]. Two of the common features of these
devices have been that their manufacture requires precision work or exotic materials and
that their installation demands specialized training. Consequently, the additional expense
in using such devices has prevented their wide acceptance in engineering practice. The
development of the Slotted Bolted Connections (SBCs) as energy dissipators represents an
attempt to overcome the abovementioned shortcomings of these systems. SBCs, as presented
in this paper, require only slight modification of standard construction practice, and require
materials that are widely available commercially.
In this paper a Slotted Bolted Connection (SBC), see Figure 1, refers to a bolted connection
where the elongated holes or slots in the main connecting plate, in which the bolts are
seated, are parallel to the line of loading. In addition a Belleville washer [8] is placed under
the nut. Two types of SBC specimen are discussed in this paper, one with brass insert plates
and one without. Upon tightening of the bolts, the main plate is "sandwiched" directly
between either the brass insert plates or the outer steel plates. The holes in the brass insert
plates and in the steel outer plates are of standard size. When the tensile or compressive
force applied to the connection exceeds the frictional forces developed between the frictional
surfaces, the main plate slips relative to either the brass insert plates in the case of the first
type specimen or the outer steel plates in the case of the second. This process is repeated
with slip in the opposite direction upon reversal of the direction of force application. Energy
is dissipated by means of friction between the sliding surfaces. Application of cyclic loads of
magnitude greater than the slip force results in approximately rectangular hysteresis loops.
The earliest investigations of SBCs as energy dissipators date back to 1976 when a series of
experiments were carried out at San Jose State University (SJSU) [1] on specimens similar
in concept to those presented here. The term SBC used here is adopted from the report
by T. F. Fitzgerald, et al. [3]. A number of other researchers have also investigated similar
devices [2, 5].
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