International Journal of Structural Engineering (11 papers in press)

Regular Issues

• Evaluation of the performance of seismically strengthened and prestressed exterior beam-column joints  
  by Pradeep M. Yeole, Yogesh D. Patil, Yuvaraj L. Bhirud 
  Abstract: Reinforced concrete (RC) beam-column joints (BCJs) are crucial in moment-resisting frames but are vulnerable to seismic damage. This study introduces a novel external diagonal prestressing technique using high-strength steel strands to improve the seismic performance of ductile-detailed exterior BCJs. The method is minimally invasive, cost-effective, and requires minor structural changes. Six full-scale BCJ specimens were tested under reverse cyclic loading: one control and five with varying prestressing levels (040%). The specimen prestressed at 30% showed a 70.37% increase in ultimate load and a 263% rise in initial stiffness. Prestressed joints had slower stiffness degradation and greater energy dissipation in early cycles. The failure mode shifted from brittle joint shear to ductile beam flexure, enhancing seismic resilience. The diagonal prestressing induced axial compression in the beam, improving joint shear strength. Overall, the technique provides a practical and effective alternative to traditional retrofitting methods for enhancing earthquake resistance in RC joints.
  Keywords: reinforced concrete; prestressing; hysteretic behaviour; energy dissipation; flexibility; stiffness; retrofitting; seismic performance.
  DOI: 10.1504/IJSTRUCTE.2026.10076736
   
  
• Tri-waste geobrick innovation: performance evaluation of earth bricks over laterite, crushed palm seed, and rice husk ash  
  by K. Chithra, M. Bhuvaneshwari 
  Abstract: Climate change, escalating construction demand, and increasing resource scarcity have intensified the need for sustainable and low-cost building materials, particularly in climate-vulnerable regions. Conventional fired clay bricks are energy-intensive, non-renewable, and associated with high greenhouse gas emissions, while offering limited thermal resistance and environmental adaptability. Addressing these limitations, this study proposes a novel tri-waste geo-brick formulated using laterite, crushed palm seed (CPS), and rice husk ash (RHA) as an unfired compressed stabilised earth brick (CSEB). Five mix combinations were developed using Taguchi experimental design and evaluated through ASTM/EN standards, supported by SEM, XRD, FTIR, life-cycle assessment, and cost-benefit analysis. Results indicate that mix 4 and mix 5 achieved optimal performance, with 5.4 MPa compressive strength, 1.21 W/m
  Keywords: compressed stabilised earth brick; CSEB; rice husk ash; RHA; crushed palm seed; CPS; laterite; sustainable building material; thermal conductivity; SEM; XRD; life-cycle assessment; LCA; cost-benefit analysis.
  DOI: 10.1504/IJSTRUCTE.2026.10077245
   
  
• Compressed steel fibre-reinforced concrete slab in joint of steel-concrete composite frame structure  
  by Petr Červenka, Jakub Dolejš 
  Abstract: This paper deals with a steel fibre-reinforced concrete (SFRC) slab in compression as a composite steel-concrete frame joint component. Based on the results of an experiment with a realistic-sized steel-concrete specimen, a numerical model has been validated in Atena Science. Based on a parametric study with these models, an analytical relationship was derived for the resistance and stiffness of the steel fibre-reinforced concrete slab in compression. In contrast to the standard procedure given in Annex C of EN 1998-1:2004 (Eurocode 8), the new procedure is designed for a steel fibre-reinforced concrete slab. The proposed analytical solutions give approximately 20% higher values of the resistance and initial stiffness factor than the results calculated according to EN 1998-1:2004 (Eurocode 8) and EN 1993-1-8:2005 (Eurocode 3).
  Keywords: composite steel-concrete frame; steel fibre-reinforced concrete; SFRC; composite steel-concrete joint; slab in compression; effective width; earthquake; FEM.
  DOI: 10.1504/IJSTRUCTE.2026.10077685
   
  
• Microbially induced carbonate precipitation for soil improvement: factorial analysis, shear testing and characterisation  
  by K. Prakash Chandra, Joga Suryaprakash Reddy, K. Mallikarjuna Rao 
  Abstract: Soil improvement utilising microbially induced calcite precipitation technologies is currently attracting a lot of attention in the geo-environmental and geotechnical fields. The purpose of this study is to evaluate how critical parameters influence calcite precipitation, and ensuing improvement in the mechanical characteristics of very loose fine sand. The impact of curing period, soil saturation level, and cementation solution molarity on calcite precipitation are evaluated using a 24 factorial experimentation design. Direct shear tests were conducted to evaluate strength and deformation characteristics. Microstructural characterisation was performed using scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction. The effect of any given factor is influenced by the level of other factors indicating that interaction effects also influence calcite produced. MICP offers a promising avenue to address soil. Related challenges while reducing the environmental impact of traditional stabilisation methods as demand for environmentally conscious soil stabilisation techniques grows.
  Keywords: MICP; saturation ratio; optical density; cementation molarity; curing period.
  DOI: 10.1504/IJSTRUCTE.2026.10077709
   
  
• Parametric study on lateral load response of reinforced concrete tube-in-tube buildings with variable column spacing and beam depth  
  by Polu Sreevarsha, K.L. Radhika, Syed Majid Hashmi 
  Abstract: This study investigates the structural behaviour of reinforced concrete tube-in-tube buildings subjected to lateral loads by varying column spacings (2.5 m, 3 m, 5 m, 6 m) and beam depths (800 mm, 1,000 mm, 1,200 mm, 1,500 mm). A 200-metre-tall building located in India, situated in Seismic Zone III and Wind Terrain Category 4, is analysed using ETABS Version 21 software. The parametric model incorporates four different column spacings and four beam depths. Earthquake analysis is conducted using the linear dynamic response spectrum method, while wind load analysis is carried out using the linear dynamic wind gust method. The results indicate that decreasing column spacing and increasing beam depth significantly reduce lateral displacements, inter-story drifts, and fundamental time period. Furthermore, as the stiffness of the outer tube increases, the shear lag effect diminishes, resulting in greater load transfer to the outer tube and reduced internal forces on the inner tube.
  Keywords: lateral load resisting system; shear-lag effect; tall building; tube-in-tube building.
  DOI: 10.1504/IJSTRUCTE.2026.10077914
   
  
• Structural performance of inclined headed shear stud in steel-concrete composite construction: an experimental investigation  
  by Md. Seragul Islam, Md. Naimul Haque, Md. Rabiul Alam, Md. Saiful Islam 
  Abstract: Headed shear studs welded perpendicular to steel beam flanges are widely used in steel-concrete composite construction, and their load transfer mechanisms are well understood. However, the influence of stud inclination on structural performance remains unclear, despite practical construction constraints that often prevent perfectly vertical installation. This study experimentally investigates the behaviour of inclined headed shear studs. Eight push-out specimens with stud inclinations of 0, 15, 30, and 45 were tested. Results show that ultimate shear resistance decreased by 23.38%, 37.57%, and 50.45% for 15, 30, and 45 inclinations, respectively, compared to vertical studs. Conversely, inclined studs exhibited enhanced ductility, with maximum slip values ranging from 16.29 to 19.95 mm, exceeding the 6 mm limit specified in BS5400. Experimental shear strengths were also compared with predictions from existing design codes, leading to meaningful conclusions.
  Keywords: inclined headed shear stud; composite beam; load-slip behavior; ductility; push-out test.
  DOI: 10.1504/IJSTRUCTE.2026.10077915
   
  
• The rheological, mechanical and durability behaviour of high strength Pozzolana lightweight self-compacted concrete mixed and effect exposure to high temperatures and cycles of freezing and thawing  
  by Laith M. Daradkeh, Ahmed Ashetyat, Mu'tasime Abdel-Jaber, Nasim Shatarat 
  Abstract: This study investigates the influence of Pozzolana on the rheological, mechanical, and durability properties of self-compacting concrete (SCC). Cast specimens included 66 cubes and 15 cylinders prepared from six different mix proportions containing varying percentages of Pozzolana. The specimens were tested for compressive strength, water absorption, ultrasonic pulse velocity (UPV), and flexural strength. In addition, durability performance was evaluated under elevated temperatures (25 C, 400 C, and 600 C) and 200 freeze-thaw cycles. The rheological properties of fresh Pozzolana self-compacting lightweight concrete were examined using slump flow and L-box tests. Results indicate that increasing Pozzolana content improves the rheological behaviour and enhances compressive strength, reaching an increase of about 20%. The optimal Pozzolana mixture achieved approximately 15% higher compressive strength than the control mix. Furthermore, Pozzolana improved durability characteristics, reducing water absorption and increasing ultrasonic pulse velocity of the concrete.
  Keywords: Pozzolana; lightweight; high strength; high temperature; freeze and thaw; self-compacting concrete; SCC; ultrasonic pulse velocity; UPV; experimental study.
  DOI: 10.1504/IJSTRUCTE.2026.10077979
   
  
• A study on modulus of elasticity and Poissons ratio of GGBFS-metakaolin-based geopolymer concrete  
  by Mohd. Nazim Raza, Syed Saifuddin, Qamar Sultana, Asma Sultana, Moahmmed Arif Hussain, Shaik Amaan, Mohammed Abraar 
  Abstract: Cement production contributes nearly 8% of global CO emissions, driving the need for sustainable alternatives. Geopolymer concrete (GPC) replaces cement with industrial by-products such as ground granulated blast furnace slag (GGFBS) and metakaolin, which provide silica and alumina for geopolymerisation. GPC also reduces water usage through sunlight, oven, or ambient curing. This study investigates the modulus of elasticity and Poissons ratio of GGFBS-metakaolin-based GPC in two phases. In the first phase, eight mixes were prepared with binder ratios of GG70-MK30 and GG80-MK20, maintaining 12M NaOH and varying coarse aggregate content (5080%). Tests on fresh and hardened concrete showed optimal performance for GG80-MK20 with 70% aggregates. In the second phase, a linear regression model was developed to predict both properties. Compared to previous studies with errors exceeding 20%, the proposed model achieved errors below 20% and is applicable for 10M and 12M GPC at 28 days.
  Keywords: geopolymer concrete; GPC; ground granulated blast furnace slag; GGBFS; metakaolin; modulus of elasticity; Poisson’s ratio; regression analysis.
  DOI: 10.1504/IJSTRUCTE.2026.10078011
   
  
• Analysis of bond characteristics between keramzit concrete and GFRP rebars with geometrical property variations using pull-out test.  
  by Sy-Quan Tu, Dang-Quang Ngo, Thuy-Chi Dang, The-Truyen Tran, Hoang-Quan Nguyen, Huy-Cuong Nguyen 
  Abstract: Among the properties of concrete members, the bond behaviour of the reinforcement to the surrounding concrete is an important parameter. In the case of lightweight concrete, many studies and specifications recommend a certain diminution of bond behaviour. It is noticed that the lightweight gravel as keramzit used instead of coarse aggregate in concrete has been gradually applied in construction works, significantly reducing the weight of the substructure and saving the costs related to the mounting as well as the foundation. Thus, many pull-out tests have been carried out on the lightweight concrete specimens with different rebar diameters and embedded lengths. Based on the obtained results, the effects of tested parameters on the bond strength and development length of GFRP rebar and lightweight concrete can be specified. The failure mode and bond mechanism of the experimental specimens are compared to the simulation results given by Atena 3D software, which helps to make many recommendations for design work.
  Keywords: development length; bond behaviour; lightweight concrete; LWC; keramzit gravel; GFRP rebar; pull-out tests.
  DOI: 10.1504/IJSTRUCTE.2026.10078205
   
  
• Development of robust mathematical models for sustainable polypropylene fibres reinforced geopolymer concrete  
  by Hamza Waheed, Kong Fah Tee 
  Abstract: Sustainable alternatives to ordinary Portland cement concrete have gained significant attention due to their potential to reduce CO2 emissions. Fly ash-based geopolymer concrete is a promising option; however, reliable strength prediction is essential for its wider application. This study develops mathematical models to predict the mechanical properties of polypropylene (PP) fibre-reinforced geopolymer concrete. Sixteen mixes were prepared with constant NaOH molarity (14 M) and sodium silicate-to-sodium hydroxide ratio (1.5), while varying alkaline activator-to-fly ash ratio (0.40.7) and PP fibre content (01.5%). A total of 48 cylinders and 48 prisms were tested. Linear, multi-linear, and non-linear (power and exponential) regression analyses were performed to relate compressive strength, tensile strength, and elastic modulus to mix parameters, with one-way ANOVA used to validate the models. Results indicate that non-linear models provide superior prediction accuracy for elastic modulus, and that AA/FA ratio and PP fibre content significantly influence mechanical performance.
  Keywords: geopolymer concrete; GPC; regression analysis; polypropylene fibres; mathematical modelling; compressive strength; tensile strength; elastic modulus; non-linear regression analysis.
  DOI: 10.1504/IJSTRUCTE.2026.10078228
   
  
• A comprehensive review of AI-driven techniques for modelling the mechanical and durability performance of high performance concrete  
  by Gaurav P. Gohil, Indrajit N. Patel 
  Abstract: High-performance concrete (HPC) is widely adopted for its superior compressive, flexural, and durability characteristics, yet its complex mix design makes performance prediction challenging. This review synthesises recent advances in artificial intelligence (AI), machine learning (ML) and deep learning (DL) techniques applied to HPC property prediction. The analysed studies considered key input variables such as cement content, water-to-binder ratio, aggregate proportions, mineral admixtures (fly ash, silica fume, slag), superplasticisers, and curing conditions. Comparative analysis of different AI models revealed that support vector machine (SVM) and M5P model tree achieved the best predictive accuracy for compressive strength, with performance values up to R2 = 0.9913 and RMSE = 2.158, significantly outperforming traditional regression methods (R2 < 0.70). In durability predictions, gradient boosted regression trees (GBRT) and deep neural networks (DNN) demonstrated high reliability, reaching R2 = 0.970 for carbonation depth and chloride penetration resistance. The novelty of this review lies in its integrated comparison of AI techniques for both mechanical and durability properties of HPC, highlighting the superiority of AI-driven approaches over conventional testing and pointing to future opportunities in hybrid models, explainable AI, and real-time monitoring to optimise next-generation HPC design.
  Keywords: high performance concrete; machine learning; artificial intelligence; deep learning; durability; prediction.
  DOI: 10.1504/IJSTRUCTE.2026.10078346