This study proposes a novel dual-functional floating-base overhead water tank (FBOWT) system capable of simultaneously mitigating seismic vibrations and harvesting energy. Traditionally serving only as storage, overhead water tanks (OWTs) are re-engineered here to utilize liquid sloshing dynamics for dual performance. The floating-base configuration maintains a constant water depth, thereby ensuring frequency compatibility between the sloshing frequency and the building's fundamental frequency, which enhances damping efficiency. Unlike conventional tuned liquid dampers (TLD), the proposed FBOWT integrates an electromagnetic energy harvesting mechanism, enabling simultaneous vibration control and renewable energy generation under seismic excitation. The coupled interaction among the structure, sloshing fluid, and integrated electromagnetic energy harvester (EEH) is formulated as a two-degree-of-freedom (2DOF) system, where energy is extracted from the relative motion between the sloshing liquid and the structure. A twelve-storey, three-bay reinforced concrete (RC) building equipped with a rooftop FBOWT is analyzed under two recorded earthquake excitations. Results demonstrate reductions of up to 36.5% in RMS displacement and 24.7% in RMS acceleration compared with the uncontrolled structure, while simultaneously harvesting up to 4.03 kJ of electrical energy under the stronger ground motion (GM1). The proposed system provides a sustainable, retrofittable, and self-powered solution for enhancing both structural resilience and energy efficiency in earthquake-prone regions.

This study investigates the effects of polyolefin macro-fibers (PO) and their combination with polypropylene micro-fibers (PP) on the mechanical properties, flexural performance, impact resistance, and specific durability parameters of self-compacting lightweight concrete (SCLC). To achieve this, ten mixtures were considered, comprising PO fibers at volume fractions of 0.2%, 0.4%, and 0.6%, with some portions replaced by PP fibers at volume fractions of 0.1% and 0.2%. The properties of the mixtures were assessed through compressive strength, flexural strength, and impact resistance tests at 28 days of age. Additionally, durability properties were evaluated using water absorption and electrical resistivity tests. The research results indicate that PO and PP fibers do not significantly affect the compressive strength of SCLC. However, PO fibers notably enhance flexural properties and impact resistance. Using 0.6% PO demonstrates a remarkable 317% improvement in flexural strength. Furthermore, 0.6% PO increases energy absorption during impact at the first crack and collapse by 84% and 274%, respectively. While PP fibers have minimal effect on the energy absorption of SCLC, their combination with PO positively affects toughness and impact resistance. PP fibers contribute to a reduction in water absorption, whereas PO fibers increase water absorption. Replacing PO fibers with PP fibers helps control the excessive water absorption associated with using PO macro-fibers at the initial and final stages. Moreover, the inverse relationship between electrical resistivity and water absorption was confirmed.

A novel approach for identifying damage in plate-like structures by analysing variations in modal parameters, utilizing a newly developed Extended Improved Particle Swarm Optimization (EIPSO) technique is presented in the present work. Initially, a finite element based numerical model is developed for an isotropic plate and validated through experimental testing. Structural damage is then introduced in the plate, and the EIPSO algorithm is employed to optimize an objective function derived from comparing the modal characteristics of the damaged and undamaged states to enable precise localization and quantification of the damage. The effectiveness and the reliability of the proposed method is demonstrated through experimental results obtained for an isotropic cantilever plate, confirming its potential in structural health monitoring (SHM) applications.

This paper presents an analytical study of the free vibration of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) microbeams containing multiple cracks, combining Euler-Bernoulli beam theory with nonlocal elasticity theory to account for size-dependent effects. Multiple cracks are modeled as rotational springs located at prescribed positions, dividing the microbeam into several sub-regions and enabling an efficient analytical treatment of crack-induced flexibility. The material properties are assumed to vary continuously through the thickness according to a power-law distribution of carbon nanotube (CNT) volume fraction, while nonlocal effects are incorporated via a characteristic length-scale parameter. Closed-form expressions for natural frequencies are derived for various boundary conditions. Numerical results demonstrate that the presence of multiple cracks significantly reduces the natural frequencies, particularly for deeper cracks and those located near regions of maximum bending moment, while nonlocal effects further soften the structural response when the beam dimensions are comparable to the intrinsic material length scale. It is also shown that appropriate functional grading of CNT reinforcement, especially with higher CNT concentration near the microbeam surfaces, can effectively enhance stiffness and mitigate the adverse effects of cracks and size dependency. The proposed formulation is applicable to slender FG-CNTRC microbeams where shear deformation effects are negligible and is particularly relevant for vibration analysis and design of MEMS/NEMS components operating at the microscale. The proposed analytical model provides useful insights and design guidelines for FG-CNTRC microbeams employed in microscale structural systems where defects and size effects cannot be neglected.