ADVANCED DAMAGE PLASTICITY MODELLING AND CALIBRATION STRATEGIES FOR ACCURATE FINITE ELEMENT ANALYSIS OF UNREINFORCED CONCRETE IN THIN WALLED STRUCTURES

Abstract

Accurate prediction of unconventional, unreinforced concretes in three‑dimensional finite‑element analysis demands a synthesis of advanced constitutive theory, rigorous experimental calibration, and careful numerical implementation. This study consolidates recent progress and remaining challenges in modeling slag‑blended, recycled‑aggregate, fiber‑reinforced, and ultra‑thin formwork concretes within the ANSYS environment. A literature survey identifies three dominant strategies for plain concrete: the legacy smeared‑crack SOLID65 element, generalized Drucker–Prager plasticity with user‑defined damage, and detailed mesoscale representations that resolve aggregates, mortar, and interfaces. Comparative findings show that damage‑plasticity formulations, exemplified by the Concrete Damaged Plasticity (CDP) model, reproduce load–deflection responses and crack patterns within fifteen percent of experimental results when parameters are calibrated against comprehensive test sets that include compression, tension, fracture, and time‑dependent data. Calibration protocols remain inconsistent across studies, hindering re-producibility and cross‑comparison. The absence of an open benchmark database for non‑standard concretes is highlighted as a key barrier to consensus on default parameters. Thin‑walled elements expose additional difficulties: geometric nonlinearity couples with pro-gressive stiffness degradation, causing mesh‑dependent fracture energy dissipation and solver convergence issues. Remedies include refined through‑thickness meshes, nonlocal regulariza-tion, and robust arc‑length solution controls. Explicit crack‑tracking techniques such as phase‑field fracture and cohesive segments offer improved fidelity, especially for fiber‑rich mixes where residual tensile capacity governs serviceability, yet systematic validation of these methods remains sparse. Long‑term phenomena such as creep, shrinkage, and durability, along with high‑rate behaviors under impact and seismic loading, are underrepresented in current model verification, particularly for slag‑rich and recycled‑aggregate mixes. A practi-cal roadmap is proposed that integrates five core actions: creation of a public benchmark da-tabase with fully documented laboratory tests; development of unified modeling protocols that specify calibration sequences, error metrics, and reporting formats; targeted investment in explicit fracture models for thin and fiber‑reinforced members; expansion of long‑term and dynamic experimental programs; and adoption of machine‑learning tools to automate pa-rameter identification and flag anomalous model behavior. Complementary software ad-vances, including plug‑and‑play material subroutines and graphical calibration wizards, are recommended to lower the expertise threshold for practicing engineers. Collectively, these measures chart a pathway from current academic advances toward robust, industry‑ready simulations capable of guiding the design of sustainable, reinforcement‑free concrete struc-tures.