The seismic repair and/or
strengthening philosophy generally consist of a) system behavior
improvement and b) member repair/strengthening. Although these two
general approaches can be applied separately in some cases, they
generally are combined. In the system behavior improvement technique,
the general philosophy is to introduce a new lateral load resisting
system, which will increase the lateral strength and the lateral
stiffness of the existing system, which is generally a non-ductile frame
with inadequate lateral stiffness. This principle relies on the safety
of the existing structure under gravity loads. Various techniques based
on this principle have been developed and applied in the past. Among
them, the most widely used technique is the formation of new stiff walls
through infilling some bays of the existing frame with reinforced
concrete infills. In general, the new stiff elements are placed in such
a manner as to minimize the floor torsion. Use of infilled frames as a
method of seismic behavior improvement for existing structures is
presently a very common application in Turkey. This approach was first
proposed following the pilot tests made by the METU staff
on the infilled frames, and was gradually established in practice on the
basis of the underlying experimental research. In addition, the column
jacketing is among the commonly used repair/strengthening techniques in Turkey. The efficiency
of the method was investigated by a number of test series
concentrating on various aspects of the problem.
All these
techniques are applicable at the cost of a certain discomfort to the
occupants and, the application of these techniques in the rehabilitation
of undamaged buildings may not very practical. In the scope of this
research project, the development of new strengthening techniques is one
major achievement. For this purpose experimental research programs will
be initiated. In these research programs the use of new materials in
system and member rehabilitation will be studied. It is intended to
perform quasi-static tests on model frame structures, aiming at the
investigation of the post intervention seismic behavior of frames
retrofitted with various techniques to be proposed.
Besides overall
system behavior improvement, repair and/or strengthening of some
reinforced concrete elements is sometimes required if their capacities
are not sufficient to meet the strength demand of a major earthquake. In
the past, many methods were proposed for strengthening of R/C members.
Depending on the desired earthquake resistance, the type of elements and
their connections members can be repaired and/or strengthened by epoxy
injection, by jacketing or fiber reinforced plastics (FRP) or carbon
fiber (CF) wrapping.
Another objective
of the proposed study is to develop alternative and yet feasible member
strengthening techniques for structures in
service.
At the end of
these studies, rapid and yet reliable rehabilitation methodologies for
Turkey will be
developed.
