Faculty Publications

Now showing 1 - 3 of 3

Time-dependent safety performance of reinforced concrete structures
(Emerald Group Holdings Ltd., 2020) Worabo Woju, U.W.; Balu, A.S.
Purpose: Performance of the structure depends on design, construction, environment, utilization and reliability aspects. Other factors can be controlled by adopting proper design and construction techniques, but the environmental factors are difficult to control. Hence, mostly in practice, the environmental factors are not considered in the analysis and design appropriately; however, their impact on the performance of the structures is significant along with the design life. It is in this light that this paper aims to perform the time-dependent performance analysis of reinforced concrete structures majorly considering environmental factors. Design/methodology/approach: To achieve the intended objective, a simply supported reinforced concrete beam was designed and detailed as per the Euro Code (EC2). The time-dependent design parameters, corrosion parameters, creep and shrinkage were identified through thorough literature review. The common empirical equations were modified to consider the identified parameters, and finally, the time-dependent performance of reinforced concrete beam was performed. Findings: Findings indicate that attention has to be paid to appropriate consideration of the environmental effect on reinforced concrete structures. In that, the time-dependent performance of reinforced concrete beam significantly decreases with time due to corrosion of reinforcement steel, creep and shrinkage. Originality/value: However, the Euro code, Ethiopian code and Indian code threat the exposure condition of reinforced concrete by providing corresponding concrete cover that retards the corrosion initiation time but does not eliminate environmental effects. The results of this study clearly indicate that the capacity of reinforced concrete structure degrades with time due to corrosion and creep, whereas the action on the structure due to shrinkage increases. Therefore, appropriate remedial measures have to be taken to control the defects of structures due to the environmental factors to overcome the early failure of the structure. © 2020, Emerald Publishing Limited.
Fuzzy uncertainty and its applications in reinforced concrete structures
(Emerald Group Holdings Ltd., 2020) Worabo Woju, U.W.; Balu, A.S.
Purpose: The aim of this paper is mainly to handle the fuzzy uncertainties present in structures appropriately. In general, uncertainties of variables are classified as aleatory and epistemic. The different sources of uncertainties in reinforced concrete structures include the randomness, mathematical models, physical models, environmental factors and gross errors. The effects of imprecise data in reinforced concrete structures are studied here by using fuzzy concepts. The aim of this paper is mainly to handle the uncertainties of variables with unclear boundaries. Design/methodology/approach: To achieve the intended objective, the reinforced concrete beam subjected to flexure and shear was designed as per Euro Code (EC2). Then, different design parameters such as corrosion parameters, material properties and empirical expressions of time-dependent material properties were identified through a thorough literature review. Findings: The fuzziness of variables was identified, and their membership functions were generated by using the heuristic method and drawn by MATLAB R2018a software. In addition to the identification of fuzziness of variables, the study further extended to design optimization of reinforced concrete structure by using fuzzy relation and fuzzy composition. Originality/value: In the design codes of the concrete structure, the concrete grades such as C16/20, C20/25, C25/30, C30/37 and so on are provided and being adopted for design in which the intermediate grades are not considered, but using fuzzy concepts the intermediate grades of concrete can be recognized by their respective degree of membership. In the design of reinforced concrete structure using fuzzy relation and composition methods, the optimum design is considered when the degree of membership tends to unity. In addition to design optimization, the level of structural performance evaluation can also be carried out by using fuzzy concepts. © 2020, Emerald Publishing Limited.
Fracture mechanics-based meshless method for crack propagation in concrete structures
(Elsevier Ltd, 2025) Paul, K.; Balu, A.S.; BabuNarayan, K.S.
Concrete is one of the most versatile construction materials, characterized by its high compressive strength and durability. It exhibits complex fracture behaviours in the non-linear region of the fracture process zone (FPZ) near crack tip, where micro-cracking, crack coalescence, and eventual macro-crack propagation occurs. Accurately predicting crack initiation and propagation in concrete structures is essential for ensuring their safety and performance. Traditional methods like finite element analysis (FEM) face challenges in capturing crack propagation due to the need for mesh refinement, which can be computationally expensive. This study aims to address this limitation by introducing the Element-Free Galerkin (EFG) method, which offers a more efficient approach for modelling crack behaviour in concrete beams. The maximum stress theory was used as the fracture criterion and the cohesive zone model (CZM) with a bilinear softening curve is employed to simulate the FPZ. Numerical examples of simply supported beam and cantilever beams with varying pre-notch positions and loadings were analysed. The results show that under axial and point loading, the stress intensity factor increases with crack length until unstable crack growth, leading to failure. The EFG method is found to be more accurate than FEM, particularly in regions with higher deformations, with a 13 % variation due to remeshing in FEM. Under point loading, EFG predicted deformation patterns with a 6 % variation in maximum deflection. This study demonstrates that the EFG-based model effectively predicts catastrophic failures, offering a computationally efficient solution for real-world concrete structures with pre-existing cracks or defects. © 2025 Institution of Structural Engineers

Faculty Publications

Browse

Filters

Settings

Sort By

Results per page

Search Results