IMPORTANCE OF MEASURING STRUCTURAL RESPONSE & GROUND VIBRATION, DURING SEVERE SEISMIC CONDITIONS:::SAEA-Technical Paper by Eng. Anjum Zafar:::

[Engineer.Anjum.Zafar]

IMPORTANCE OF MEASURING STRUCTURAL RESPONSE & GROUND VIBRATION, DURING
SEVERE SEISMIC CONDITIONS:::SAEA-Technical Paper by Eng. Anjum
Zafar:::


Instrumentation is a very important aspect of experimental
investigation to measure the responses of structures as well as the
ground. It helps researchers in understanding the structural behavior
in a better manner which may lead to the evolution of rational design
guidelines which will benefit the society in having safer structures.
A variety of instruments from ordinary to sophisticated ones are
available in SAEA-NYC Center for the purposes of measuring various
quantities relating to structural and geotechnical responses, in AJK
or elsewhere in the world… where ever Earthquake Resistant Structures
are being executed. This Technical Paper, from the Society of American
Engineers in Asia [SAEA] presents quite interesting applications of
instrumentation to measure responses of a wide variety of structural
components ranging from the determination of stress-strain
characteristics of steel bar to hot spot stress in welded tubular
joint. It also discusses as how sophisticated instruments were used to
measure the ground vibration induced by pile driving. There is an open
invitation to all the engineers throughout the world, by SAEA, to come
forward and participate in our discussion

To explain, it must be understood that structures are built basically
to serve some functional needs. In this process, generally, they are
acted upon by dead and live loads. These loads induce strain and
stress in the material of the structures. From the safety point of
view, the magnitudes of the induced stresses have to be within some
permissible levels. Several standards and codes of practices that
prescribe permissible levels of induced stresses in structures are
available for the guidance of esigners.Sometimes structures are also
subjected to time dependent loads like earthquakes, wind5 and waves6.
Abnormal loads like blast and impact8 also,occasionally, act on
structures. These time dependent loads, called dynamic loads, excite
the structures and set them in motion. The magnitude of the vibration
level epends on the magnitude of the applied dynamic loads and the
time period of the structure. From the point of view of safety, the
vibration level has to be within the permissible level. Threshold
vibration limits for the safety of structures, excited by time
dependent loads are available in the form of standards. Many times
underground shock loads, such as, underground blasting, tunneling,
hydraulic compaction, pile driving, traffic induced impact, and
aircraft landing, induce ground motion which in turn will excite the
structures founded on it. These ground vibrations are also harmful to
the structures. Therefore, it is all the more essential to measure
these quantities, such as, strain, stress, displacement, and vibration
level, to determine their severity. Hence, sensors and transducers are
made use of to measure various quantities. These sensors are connected
to various amplifiers, meters and data recorders to collect various
data during testing of structures, both in the laboratory and also in
the field:::<>:::

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Submitted by:::Eng. Anjum Zafar, M.Sc(Engrg.) FIE CEng MICE(UK)
President:::<SAEA>:::
For:::NYC Center [United States]
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