## 1 Introduction
Most such uses for column members under dynamic loading have involved the monitoring of structural health using piezoelectric-based sensors. [PERSON] et al. [7] used pre-embedded and post-embedded piezoceramic transducers to perform crack-based damage quantification in full-size high-strength RC column specimens under cyclic loading. They found that pre-embedded piezoceramic transducers were more sensitive to maximum residual crack width than were the post-embedded piezoceramic transducers, especially for shear cracks. They also found that piezoceramic transducers are not suitable for the SHM of severely damaged RC columns. The values of the damage indices that were obtained using such sensors were more strongly correlated with crack width. [PERSON] et al. [7] introduced a normalized damage index, which they referred to as the \"crack damage index\", and suggested a limiting value of this damage index at each damage level. Their results revealed that the proposed piezoceramic transducer has potential for use in the SHM of an RC column. In addition to structural health monitoring, the piezoelectric sensors could be used for seismic stress measurements and bond slip of the steel elements of the RC structure, the detection of bolt loosening, pre-load degradation of the bolt connection, etc. Entropy-based active sensing and the genetic algorithm-based least square support vector machine using PZT sensors have been developed by [PERSON] et al. [8] for detecting the looseness of multi-bolt connections. The smart aggregates (SAs)-based active sensing method was adopted by [PERSON] et al. [9] to study the development of bond slip between the steel plate and concrete of the composite structure. [PERSON] et al. [10] and [PERSON] et al. [11] also investigated the bond slip behaviors of steel-concrete composite structures using different approaches. The piezoelectric transducer also can be utilized as an energy harvester [12; 13; 14; 15] or passive vibration damping controller [16; 17]. For earthquake engineering research, it is essential to evaluate the damage states or to validate the analyzed results by monitoring the structural, internal stress responses during an earthquake. The study of stress monitoring with transducers for structural engineering, aerospace engineering, and robotics has drawn increasing interest from academia and industry. [PERSON] et al. [18; 19] proposed a seismic stress sensing system by utilizing the PZT-based smart aggregates to measure the compressive seismic stress and shear stress of low-to-middle-rise RC structures under earthquakes. The force/torque sensors using piezoelectric material for the aerospace engineering application have been developed by [PERSON] et al. [20]. [PERSON] et al. [21] proposed a force/torque sensor based on beam theory and optoelectronic technology for robotics. [PERSON] et al. [22] studied the influence of non-uniform stress fields on seismic stress measuring using PZT-based smart aggregates. [PERSON] et al. [23] presented an in-built piezoelectric-based three-direction stress sensor to monitor the internal normal stresses in three directions, and the finite element analysis was performed to investigate the stress transfer inside the sensor. However, research on the internal force detection of RC structures under dynamic loadings is scarce. To quantify damage to an RC column member after an earthquake and to elucidate crack development in a column member, the maximum force that was applied on it as a result of the earthquake must be known. Since the measurement of maximum loading in an earthquake is difficult, in this work, piezoceramic sensors were used to quantify the force that was applied to an RC column member under dynamic loading. Piezoelectric effects are sensitive to external vibrations, and this fact can be exploited to detect the applied force in an earthquake. Post-embedded piezoceramic sensors were formed into a distributed intelligent sensor network to measure the force that was applied to an RC column member under earthquake excitation.