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INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
MANAGEMENT & APPLIED SCIENCE (IJLTEMAS)
ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XV, Issue III, March 2026
Structural properties including configuration, elastic stiffness (EI), and deformation characteristics are also part
of the resisting system
Thus: If F≤R, the system is in static equilibrium
If F>R, the system becomes structurally unstable
Modern architecture frequently incorporates large cantilever projections for aesthetic and functional purposes.
However, such configurations are prone to loss of equilibrium and serviceability under gravity and wind loads.
Cantilever structures, while architecturally appealing, tend to experience excessive deflection and deformation
as their length increases. These structural challenges often lead to serviceability issues such as fatigue, cracking,
and reinforcement congestion, particularly when conventional reinforced concrete systems are used to maintain
static equilibrium.
Consequently, conventional RC design methods may become inefficient for large cantilever spans, necessitating
advanced analytical approaches and alternative systems such as post-tensioned (PT) slabs. This study therefore
evaluates the structural behaviour of large cantilever projections in a ten-storey building, with the objective of
determining the practicable projection limit by considering both the dynamic response and static equilibrium
requirements, using finite element modelling via ProtaStructure. Although numerous studies have addressed
serviceability performance, very few have explicitly examined the equilibrium balance between internal and
external actions in large cantilever slabs of multi-storey reinforced-concrete (RC) buildings. Most available
research has focused either on global building dynamics or on small-scale component behaviour. Consequently,
the influence of projection length and prestressing on the equilibrium and stiffness of long cantilever slabs
remains inadequately understood. This research therefore bridges that gap by assessing how post-tensioning
modifies equilibrium and stiffness under Eurocode 2 (EN 1992-1-1: 2004) load combinations, using finite-
element modelling in ProtaStructure. The study provides a comparative evaluation of RC and PT slab systems,
offering design guidance for maintaining static and dynamic equilibrium in large cantilever projections of high-
rise buildings.
LITERATURE REVIEW
Equilibrium and Structural Behaviour
Timoshenko and Gere (1961) described equilibrium as a condition in which internal moments and shear forces
counterbalance applied loads without excessive deformation. Smith and Coull (1991) further identified that the
equilibrium of a cantilever depends primarily on its flexural stiffness (EI) and projection length (L). As LLL
increases, deflection grows in proportion to L
4
, thereby reducing overall stability. Finite-element investigations
by Zhou et al. (2018) and Smith et al. (2020) confirmed that long-span cantilevers exhibit nonlinear stress
distribution at the fixed end. Jones and Wang (2015) observed that equilibrium distortion frequently arises from
secondary torsion and localised cracking. Finite-element modelling (FEM) tools such as ProtaStructure enable
detailed visualisation of these behaviours under combined dead, live, and wind loading. Lin and Burns (1981)
and Warner et al. (1998) explained that prestressing introduces counteracting compressive forces, thereby
producing an internal restoring moment that offsets external bending. Zhou et al. (2018) demonstrated that post-
tensioned (PT) slabs maintained serviceable deflection limits even for 6 m spans, validating prestressing as an
effective equilibrium-control measure.
Dynamic Equilibrium
Noushad et al. (2021), in their study on dynamic-equilibrium equations within the unified-mechanics theory
(UMT), indicated that dynamic analysis is based on Newton’s universal laws of motion. They observed that the
x, y, z space–time coordinate system does not include an explicit term for energy loss, hence an empirical
damping constant C is used in the dynamic-equilibrium equation. Energy loss in any system is governed by the
laws of thermodynamics. The unified-mechanics theory integrates Newtonian mechanics with thermodynamic
laws at an ab initio level, thereby incorporating energy dissipation (entropy generation) directly into its
governing equations. Using UMT, a dynamic-equilibrium equation was derived and validated through one-