Fiber reinforced polymer (FRP) materials are currently used for strengthening civil engineering infrastructures. The
strengthening system is dependant on the bond characteristics of the FRP to the external surface of the structure to be
effective in resisting the applied loads. This paper presents an innovative self-monitoring FRP strengthening system. The
system consists of two components which can be embedded in FRP materials to monitor the global and local behavior of
the strengthened structure respectively. The first component of the system is designed to evaluate the applied load acting
on a structure based on elongation of the FRP layer along the entire span of the structure. Success of the global system
has been demonstrated using a full-scale prestressed concrete bridge girder which was loaded up to failure. The test
results indicate that this type of sensor can be used to accurately determine the load prior to failure within 15 percent of
the measured value. The second sensor component consists of fiber Bragg grating sensors. The sensors were used to
monitor the behavior of steel double-lap shear splices tested under tensile loading up to failure. The measurements were
used to identify abnormal structural behavior such as epoxy cracking and FRP debonding. Test results were also
compared to numerical values obtained from a three dimensional shear-lag model which was developed to predict the
sensor response.
In this paper, the concept, modeling and preliminary testing of an intelligent FRP retrofit with self-monitoring
capabilities for critical civil infrastructures are presented. This intelligent system is based on an easy-to-apply
configuration of FRP pre-preg tapes with multiple stacked unidirectional layers of piezoelectric or SMA actuators and
integrated optical fiber sensors. This intelligent retrofit will be able to not only monitor conditions including bonding of
the FRP to the structure and opening of concrete cracks, but also minimize the crack opening and retard the progression
of further FRP debonding. Towards this end, a computationally efficient two-dimensional shear stress-transfer model
based on a simplified shear lag analysis is developed, with consideration of the fact that the stress transfer between the
FRP, actuator and sensor layers in the intelligent system is complex. The effectiveness of this model is demonstrated
through one numerical benchmark problem and one typical FRP configuration, with comparison of each to full threedimensional
finite element models. The agreement between the two formulations is shown to be further improved by
adjustment of the assumed shape functions. A preliminary experiment is also presented in which pre-fabricated optical
fiber ribbons are embedded into the FRP strengthening of a full-scale concrete beam. Results from static loading test of
the FRP strengthened beam show the feasibility of this technique for the self-monitoring FRP retrofits.
This paper analyzes the application of semi-active variable damping TMD (SAVDTMD) with piezoelectric friction
dampers as an alternative to existing methods to control floor vibrations, especially walking-induced vibrations. The use
of a MDOF floor model in the analysis provides some insight on the effect of modes not targeted in the design of the
controller. An optimal semi-active control law originally developed for vehicle suspension control was incorporated into
the analytical models. Two floor system examples, typical of those that would have a floor vibration problem, are
evaluated and shown to be controlled successfully by the SAVDTMD at both the targeted and untargeted modes.
Problems of spillover of the control force to untargeted modes was analyzed and determined to be stabilizing.
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