Abstract
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.
Key Words
overhead water tank; renewable energy harvesting; seismic resilience; sustainable
infrastructure; tuned liquid damper; vibration control
Address
Mithu Dey, Debanjali Hazra: Department of Civil Engineering, NITTTR Kolkata, Kolkata-700106, India
Rajib Sardar: Department of Civil Engineering, IIEST Shibpur, Howrah-03, India
Abstract
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.
Key Words
energy absorption; impact resistance; polypropylene fibers; polypropylene micro-fibers; selfcompacting
lightweight concrete
Address
Moosa Mazloom, Mahdi Molazadeh, Oveys Afzali-Naniz: Department of Structural and Earthquake Engineering, Faculty of Civil Engineering,
Shahid Rajaee Teacher Training University, I. R. Iran
Hasan Salehi: Department of Mechanical Engineering, Khatam Al-Anbia University, Tehran, Iran
Abstract
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.
Key Words
damage identification; extended improved particle swarm optimization; finite element model;
modal analysis; particle swarm optimization; Reissner-Mindlinplate
Address
Thakurdas Goswami: Department of Civil Engineering, Jadavpur University, Kolkata, 700032, West Bengal, India
Sourish Mukherjee, Partha Bhattacharya: Department of Engineering Simulation, Bentley Systems, Newtown, Kolkata 700156, West Bengal, India
Abstract
This paper presents an analytical study of the free vibration of functionally graded carbon nanotubereinforced
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.
Address
Gia-Phi Bui, Thi-Thanh-Huong Dong: Faculty of Technical Fundamental, University of Transport Technology, 54 Trieu Khuc, Hanoi, Vietnam
Van-Hieu Dang: Faculty of Mechanical Engineering and Mechatronics, Phenikaa School of Engineering,
Phenikaa University, Hanoi, Vietnam
