Since the last two decades, the electro-mechanical impedance technique has undergone extensive theoretical and experimental transformations coupled with the evolution of newer practical adaptations and variants. Notable among these are the metal wire–based variant, the dual piezo configuration and the embedded configuration, over and above the conventional surface-bonded configuration. Although there is a plethora of electro-mechanical impedance–related research devoted to metallic structures, only a limited number of studies are available for reinforced concrete structures, which are characterized by more complex behaviour and pose multiple problems for the electro-mechanical impedance sensors such as small range and high damping due to heterogeneous constitution. This article presents, for the first time, a comprehensive comparative study covering four different variants, namely, the surface-bonded single piezo configuration, the embedded single piezo configuration and the metal wire single piezo configuration in electro-mechanical impedance technique for structural health monitoring of a real-life-sized reinforced concrete beam subjected to destructive testing. The article also proposes a modified and more practical version of the dual piezo configuration called the modified dual piezo configuration, employing concrete vibration sensors. It is found that the modified dual piezo configuration is the most expedient among all variants in capturing the damage with respect to the first occurrence of cracks and the final warning of ultimate failure. Metal wire single piezo configuration is good in detecting the first level of damage; however, its efficiency ceases thereafter when crack size increases. It can be considered as an alternative to surface-bonded single piezo configuration in the scenarios where the damage level is incipient. The sensitivity of the modified dual piezo configuration increases with increasing number of actuators connected in parallel due to an increase in the output current. Also, contrary to the surface-bonded single piezo configuration, the susceptance signature of the modified dual piezo configuration is equally sensitive to damage due to the absence of capacitance part in its admittance signature. Hence, its susceptance can also be used for damage severity measurement for incipient damage level in reinforced concrete structures. The surface-bonded single piezo configuration is found to be best in quantifying damage severity in terms of the equivalent stiffness parameter. Embedded single piezo configuration and metal wire single piezo configuration, on the other hand, correlate well with the global dynamic stiffness of the structure. Overall, the proposed integration enables an early detection of damage, its propagation and improved severity measurement for reinforced concrete structures, thus contributing to new application protocols.

This paper presents a novel algorithm for compensating the changes in conductance signatures of a piezo sensor due to the temperature variation employed in condition monitoring using the electro-mechanical impedance (EMI) approach. It is crucial to consider the changes in an EMI signature due to temperature before using it for comparison with the baseline signature. The shifts in the signature due to temperature can be misinterpreted as damages to the structure, which might also result in a false alarm. In the present study, the compensation values are calculated based on experiments on piezo sensors both in a free boundary condition and in a bonded condition on a metallic host structure. The values were further validated experimentally for damage detection on a large 2D steel plate structure. The variation in first natural frequency values for the unbonded piezo sensor at different temperatures has been used to develop the compensation algorithms. Whereas, in the case of the bonded sensor, the shift in structural peaks has been used. The developed compensation relations showed promising results in damage detection. Lastly, a finite element-based study has also been performed, supporting the experimental findings. The outcome of this study will aid in the compensation of the signatures in the structure due to temperature variation in the conductance signature.

This paper presents the structural behavior of buildings located in the sloping ground level subjected to seismic load. Three different categories of building from three to five storey are considered for the numerical modelling namely set back building (SB), step back building (SBB) and step back set back building (SBSB). The dynamic response of different buildings are analyzed and compared to assess the seismic vulnerability associated with each buildings. The seismic vulnerability is accessed by comparing the base shear, drift, displacement and torsion factor values. Linear static method is used for the calculation of earthquake load using ETABS. It is observed that SBB and SBSB are highly affected by torsion compared to the SB building. It is desirable to use shear wall in periphery of the bottom storey to improve seismic performance of building. The results in this paper can be employed for construction of buildings with seismically active sloping ground.

Q and RMR systems of rock mass classifications are widely used around the world to characterize rock mass quality and to estimate preliminary rock support for underground structures like tunnels and caverns. Despite being widely used, the ratings given in these classification systems are highly subjective and are based on the judgment of the site engineers and engineering geologists. While carrying out such characterization, parameters associated with each classification system are reported in a range of values instead of a single value. On the other hand, in recent times, Geological Strength Index (GSI) has been used extensively worldwide while carrying out stability assessments of tunnels and caverns. Through this process, the GSI value is linked to different relationships proposed by different scholars. This manuscript aims to demonstrate the sensitivity of the variation of the rock mass quality ratings and their impact on the assessment of the overall stability condition of underground caverns. The in-depth assessment of the deformation condition is analyzed using numerical modelling for different GSI values from the same rock mass class classified by Q-system. For this purpose, an underground powerhouse cavern located in the higher Himalayan region is considered a case project. The powerhouse cavern is characterized by Q-system values ranging from 3 to 40 and GSI values from 44 to 73. Stability assessments are carried out using combinations of numerical, empirical, analytical, and semi-analytical approaches. The analysis indicated that the cavern remains stable, but the results exhibited notable variation due to the sensitivity of GSI as an input to the analyses. Finally, the limitations of the use of GSI in numerical modelling are comprehensively discussed.