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Research Article
Design of Reinforced Concrete Retaining Wall by Hybrid Teaching Learning Based Optimization
Honar Issa
,
Charles Camp*
Issue:
Volume 14, Issue 3, June 2026
Pages:
134-148
Received:
9 April 2026
Accepted:
25 April 2026
Published:
13 May 2026
DOI:
10.11648/j.ajce.20261403.11
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Abstract: Reinforced concrete (RC) retaining walls are widely used in civil engineering applications, where economical and efficient designs are essential, given their extensive use and material demands. This study aims to optimize the weight and cost of RC cantilever retaining walls by developing a hybrid Teaching–Learning-Based Optimization (TLBO) algorithm with enhanced performance characteristics. The proposed method introduces a multi-population selection strategy that improves exploration of the design space in early iterations and promotes convergence in later stages. In addition, a pre-generated list of feasible reinforcement configurations is incorporated to eliminate repetitive constraint checks, thereby reducing computational effort. The optimization framework considers both geotechnical and structural constraints, including stability against sliding and overturning, bearing capacity, and compliance with ACI 318-19 design requirements. Two benchmark problems—retaining walls with and without a shear key—are analyzed to evaluate the effectiveness of the proposed hybrid TLBO. The results are compared with several established optimization techniques, including genetic algorithms, particle swarm optimization, grey wolf optimization, and other heuristic methods. The findings demonstrate that the hybrid TLBO algorithm provides more consistent, near-optimal solutions, as indicated by lower standard deviation values and improved convergence. The optimized designs achieve reduced cost and weight while satisfying all design constraints, with several critical constraints approaching their capacity limits, indicating optimal resource utilization. Furthermore, the proposed modifications reduce computational time by eliminating up to 20% of constraint evaluations. Overall, the study confirms that the hybrid TLBO approach is a robust and efficient tool for the optimal design of RC retaining walls, offering superior performance compared to conventional optimization methods.
Abstract: Reinforced concrete (RC) retaining walls are widely used in civil engineering applications, where economical and efficient designs are essential, given their extensive use and material demands. This study aims to optimize the weight and cost of RC cantilever retaining walls by developing a hybrid Teaching–Learning-Based Optimization (TLBO) algorith...
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Research Article
Elastic Modulus of Concrete Produced from Selected Coarse Aggregates
Chioma Temitope Gloria Awodiji*,
Goodday Ohwofaohworaye,
Confidence Abacha
Issue:
Volume 14, Issue 3, June 2026
Pages:
149-161
Received:
11 April 2026
Accepted:
3 May 2026
Published:
14 May 2026
DOI:
10.11648/j.ajce.20261403.12
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Abstract: Frequent building collapses in Nigeria, often due to low-quality concrete with poor elasticity, have led to severe loss of lives and properties. In addition, the disposal of palm kernel shells (PKS), which is in abundant supply in some parts of the country, creates pollution and groundwater contamination. Many rural people living in the southern part of Nigeria use palm kernel shell in concrete production since it is a cheaper and very available alternative source of coarse aggregate. However, they have little or no understanding of its structural implications. This study is aimed at providing insight into the elastic modulus of concrete produced using contemporary granite aggregates and the PKS. This will aid in providing additional knowledge for the development of sustainable and green infrastructure. In this work, concrete was manufactured from Portland cement, river sand, coarse aggregates, and water. Coarse aggregates experimented were flaky granites (GC1), elongated granite (GC2), and the palm kernel shell (PKS) correspondingly. The water-cement ration (w/c) adopted were 0.45 and 0.5 for mix proportions 1: 1.5: 3, 1: 2: 3, and 1: 2: 4 respectively. Overall, the elastic modulus (EM) of the concrete produced using GC1 generated highest values for all categories of mix proportions tested. While those produced using PKS gave minimum results. The highest EM of concrete obtained was 29.12GPa at mix 1: 2: 4. 0.5 w/c. While the lowest was at 12.88GPa for 1: 1.5: 3 mix with 0.45w/c for PKS aggregates. Increase in w/c ratio slightly improved the EM of concrete produced from PKS except at mix 1: 2: 4. However, this led to a drop of EM for concrete produced using GC1 except at mix 1: 2: 4. ANOVA 2-way test showed that the choice of coarse aggregate played a major role in determining the EM of concrete, rather than the specific mix proportions. In conclusion, PKS can be used in making concrete for non-structural purposes, but the mix and water-cement ratios must be properly designed to achieve reasonable strength.
Abstract: Frequent building collapses in Nigeria, often due to low-quality concrete with poor elasticity, have led to severe loss of lives and properties. In addition, the disposal of palm kernel shells (PKS), which is in abundant supply in some parts of the country, creates pollution and groundwater contamination. Many rural people living in the southern pa...
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Research Article
Research Progress and Performance Evaluation of Repair Materials for Damaged Concrete Structures in Marine Environments
Issue:
Volume 14, Issue 3, June 2026
Pages:
162-169
Received:
13 March 2026
Accepted:
23 April 2026
Published:
15 May 2026
DOI:
10.11648/j.ajce.20261403.13
Downloads:
Views:
Abstract: Research on rapid-repair concrete for marine environments is dedicated to addressing the deterioration of infrastructure under harsh marine conditions. By developing specialty materials and processes that feature rapid hardening, early strength, high durability, and good workability, it aims to achieve swift and durable repairs of key projects such as ports and sea-crossing bridges. This shortens maintenance windows, reduces economic losses, and ensures structural safety. However, this field still faces challenges at multiple levels: at the material level, it is difficult to balance "rapidity" and "durability"; the interface between old and new concrete is weak; underwater anti-washout performance is insufficient; at the engineering level, there is poor adaptability to complex working conditions, difficulties in quality control, and a lagging standard system; at the comprehensive level, costs are high, life-cycle assessment systems are incomplete, and integration with intelligent technologies is inadequate. This research holds significant strategic and practical importance for supporting the "Maritime Power" strategy, ensuring the safety of maritime routes under the "Belt and Road" initiative, and enhancing the resilience of critical infrastructure. It is also a key practice for implementing marine ecological civilization and promoting the sustainable development of the marine economy. Future research should focus on the long-term performance evolution mechanisms under the coupled effects of materials, structures, and the environment. Efforts should be made to develop low-cost, highly compatible, and environmentally friendly repair systems, and to promote the deep integration of digital design, intelligent monitoring, and automated construction. Ultimately, the goal is to establish a comprehensive technical system for marine engineering repair that integrates rapidity, durability, and intelligence.
Abstract: Research on rapid-repair concrete for marine environments is dedicated to addressing the deterioration of infrastructure under harsh marine conditions. By developing specialty materials and processes that feature rapid hardening, early strength, high durability, and good workability, it aims to achieve swift and durable repairs of key projects such...
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