Vol.6,No.1,2026-Table of Contents
- OPEN ACCESS ARTICLE
- Load-bearing performance of laminated bamboo lumber-steel plate single-bolt connections
- Sustainable Structures Vol.6,No.1,2026 DOI:10.54113/j.sust.2026.000100 Online published:2026-1-2
- Abstract In order to investigate the mechanical properties of laminated bamboo lumber-steel plate bolted connections under compression parallel to grain, a series of tests has been carried on considering the diameter of the bolts, the thickness of the main component and the end spacing of the bolts. The failure mode, stiffness, bearing capacity and ductility ratio of the connections were studied considering the influencing factors. The test results show that the failure mode gradually changes from brittle shear failure to ductile yield failure with the increasing of the thick-to-diameter ratio. As the diameter of the bolt increased, the stiffness and load of the connections increased gradually, but the ductility ratio did not change after the diameter reached about 16 mm. The initial stiffness of the connections reached the maximum value at 125 mm thickness of the main component. The yield load and ultimate load no longer showed a significant increasing trend after the thickness reached 100mm, and the ductility ratio was less affected by the thickness of the main component than by the diameter. The end spacing of the bolts had no significant effect on the load-bearing performance of the connections compared to the bolt diameter and the thickness of the main component. Based on the test results comparing the current national wood structure design standards, the American standards are more conservative, while the Chinese and European standards are in good agreement with the test. Considering the bolt diameter and the main component’s thickness as the main influencing factors, the load-bearing formula was proposed and it could give a reference for calculating the bearing capacity of laminated bamboo lumber-steel plate single-bolt connection.… More
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- Effects of the use of recycled concrete aggregate on compressive behavior of partially encased composite columns
- Sustainable Structures Vol.6,No.1,2026 DOI:10.54113/j.sust.2026.000099 Online published:2026-1-2
- Abstract Using recycled concrete aggregate (RCA) can offer significant sustainability benefits by reducing waste and lowering the environmental impact on construction. This study presents a series of tests on short partially encased composite (PEC) columns to investigate the effects of RCA on the compressive behavior of PEC columns cast with recycled aggregate concrete. A total of 15 PEC columns and three bare steel columns were tested under concentric axial compression loads. The test incorporated five RCA replacement ratios (0%, 25%, 50%, 75%, and 100%) and three link spacing-to-depth ratios (0.33, 0.5, and 0.67). The failure modes, load-strain behavior, load capacity, and ductility were assessed to evaluate the effects of the RCA replacement ratio and link spacing. The failure mode was similar for all the PEC columns: crushing of concrete, and buckling of steel flanges. The test results indicate that columns become more brittle when the RCA replacement ratio exceeds 50% since RCA contains microcracks. However, under concentric loading, the effects of the RCA replacement ratios on column strength were negligible across different link spacing. Incorporating RCA resulted in a maximum 6% drop in strength. An increase in link spacing reduced the ultimate load for all columns. The initial stiffness was also comparable for different RCA replacement ratios and link spacings. Increasing the RCA replacement ratio increased the strain at peak load, especially for smaller link spacings. The current design guidelines for PEC columns with natural aggregate concrete can be safely used to predict the capacity of the PEC columns incorporating RCA. These findings enhance sustainable building techniques by illustrating that RCA can be utilized efficiently in PEC columns without a considerable decline in strength and stiffness.… More
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- Mechanical and thermal properties optimization of an innovative mortar incorporating PVC waste for enhanced energy efficiency
- Sustainable Structures Vol.6,No.1,2026 DOI:10.54113/j.sust.2026.000098 Online published:2026-1-2
- Abstract Given the significant environmental challenges posed by plastic waste, innovative reuse strategies are essential. This study seeks to bridge a gap in prior research by investigating the novel application of polyvinyl chloride drainage pipe waste (PVC) as a partial sand substitute in mortar, aiming to enhance both the thermal behavior and mechanical performance. Previous studies have noted that while integrating plastic waste into construction materials can enhance thermal properties, it frequently results in a reduction of mechanical strength. To address this issue, our study carefully considered the size of PVC aggregates. Seven substitution rates (0%, 5%, 10%, 15%, 20%, 25%, and 30% by weight) were evaluated through laboratory tests, including bulk density, water absorption, compressive and flexural strength, thermal conductivity, volumetric heat capacity, and thermal diffusivity. Additionally, numerical simulations using TRNSYS software on office buildings assessed the energy-saving potential. Furthermore, a multi-objective optimization approach was introduced to identify the optimal mix composition, balancing mechanical strength and thermal performance. Results showed that increasing PVC content improved thermal properties, with an optimal substitution rate also enhancing mechanical characteristics. Notably, a 30% replacement rate demonstrated significant energy savings, which could be further increased by increasing the mortar thickness.… More
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- Dimensional stability and mechanical performance of cement -mortar mix with phragmites-australis fibers at elevated temperature
- Sustainable Structures Vol.6,No.1,2026 DOI:10.54113/j.sust.2026.000097 Online published:2026-1-2
- Abstract The building structure faces the dual challenge of CO₂ emission reduction and performance/sustainability improvement of construction materials. In this respect, in recent times, interest in the incorporation of natural fibers into cementitious systems has been rising as a promising route for attaining these objectives. This paper investigates the effects of adding Phragmites-Australis (Ph-A) fibers on the properties of flexural and compressive strength and length change, including chemical shrinkage, drying shrinkage, and expansion, of cement mortar when exposed to elevated temperature (45°C). Ph-A fibers were added by volume of mix with different percentages of 0, 0.5, 1 and 2%. Furthermore, a maturity equation was used for the prediction of shrinkage behavior including ultimate shrinkage, time scale factors, and hydration rates. Experimental results revealed that the addition of 1% Ph-A fibers significantly improved flexural and compressive strength while density decreased with increasing fiber content. Besides, the addition of 2% Ph-A fibers reduced chemical shrinkage by 25%, autogenous shrinkage by 12.4%, drying shrinkage by 17.8%, and expansion by 14.9% compared to the control mix. The maturity equation presented very good agreement with the experimental data, confirming its reliability in shrinkage predictions. These results put into evidence the potential of Ph-A fibers to enhance the mechanical and dimensional performance of cement mortar, offering a sustainable solution for reducing environmental impact and advancing durable construction materials.… More
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- Post-tensioning of structural members using natural fiber ropes
- Sustainable Structures Vol.6,No.1,2026 DOI:10.54113/j.sust.2026.000096 Online published:2026-1-2
- Abstract Natural fiber composites have recently gained popularity in construction due to their numerous benefits. Their applications include incorporation into the concrete mixture, potential replacement of steel reinforcement in reinforced concrete components, and strengthening of structural elements. Notably, despite their relatively low stiffness, these materials exhibit a good load-bearing capacity in tension, indicating that post-tensioning may represent the most effective technique for employing these materials in conjunction with concrete. Surprisingly, this technology has yet to be considered in structural concrete research. The current study presents a thorough analytical, experimental, and numerical approach to assess the efficacy of post-tensioning concrete members using natural jute fiber (NJF) ropes. Preliminary analytical investigations reveal that the proposed post-tensioning can improve a beam's flexural strength by 5.9% when a single rope is used. The experimental validation supports the reliability of the analytical findings, with numerical analysis indicating a potential improvement of 16.3% when the number of ropes used on the same beam is increased to four. Overall, the enhanced flexural performance of concrete structural elements through post-tensioning with NJF ropes appears promising. This novel technique not only improves the flexural performance of concrete members but also has the potential to address critical issues related to conventional post-tensioning, such as the corrosion of steel cables. Additionally, it offers increased flexibility by facilitating the replacement of ropes when required, making it a practical and versatile solution for several concrete applications in the construction industry.… More
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- Bond of steel and FRP reinforcement in recycled aggregate concrete: a critical review
- Sustainable Structures Vol.6,No.1,2026 DOI:10.54113/j.sust.2026.000095 Online published:2026-1-2
- Abstract The use of recycled concrete aggregates (RCA) in recycled aggregate concrete (RAC) presents a solution to reduce dependence on raw natural resources. However, the bond behaviour of reinforcing bars embedded in RAC is challenging, mainly due to contradictory results in literature. This critical review examines the mechanisms influencing bond strength of steel and fibre reinforced polymer (FRP) reinforcement in RAC, emphasising key factors such as surface roughness, interaction at the interfacial transition zone (ITZ), and the concrete’s properties. Additionally, the review discusses the main differences in bond performance between FRP reinforcement and normal steel bars, highlighting the FRP bars’ reliance on adhesion and friction, rather than mechanical interlocking. Various testing methods in line with current standards are discussed, alongside relevant design equations from European and North American guidelines for anchorages and lap splices. It is found that moderate RCA replacement levels (50%-75%) can improve the bond strength of bars due to a rougher interfacial transition zone. However, high levels of RCA replacement (~100%) can reduce bond strength by up to 38%. Current design codes primarily focus on steel and FRP reinforcement embedded in normal concrete, and therefore these should be revised to extend their applicability to RAC elements to promote the faster adoption of RAC in engineering practice. Future research needs are also provided. This study contributes towards a better understanding of bond behaviour of reinforcement in RAC, which in turn is expected to facilitate the broader adoption of circular economy practices in construction.… More
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- Void content and initial surface absorption of palm kernel shell laterized concrete
- Sustainable Structures Vol.6,No.1,2026 DOI:10.54113/j.sust.2026.000094 Online published:2026-1-2
- Abstract This study investigates the viability of incorporating palm kernel shell (PKS) and laterite as sustainable replacements for conventional granite and sand aggregates in concrete. Through detailed analysis of void content and initial surface absorption, the durability and environmental suitability of PKS-laterized concrete were evaluated under varying water-cement ratios and replacement levels. Results indicate that both PKS and laterite increase void content and surface absorption, with these effects intensified at higher water-cement ratios. However, a mix containing 10% PKS and 10% laterite demonstrated durability metrics comparable to those of traditional concrete, showing strong resistance to chloride ingress and suitability for severe coastal environments. At a 0.4 water-cement ratio, PKS-laterized mixes achieved durability standards for coastal and urban applications, whereas a 0.45 ratio proved effective for moderate coastal exposures. These findings support the potential of PKS-laterized concrete as a sustainable building material, reducing reliance on natural aggregates while maintaining performance. Further research is recommended to confirm the long-term durability of these mixes across diverse environmental exposures and to refine mix designs for optimal strength and permeability. This study contributes to the field of eco-friendly construction materials, aligning with global sustainability goals and resource conservation.… More
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- Application of an original method to the design of composite beams and comparison with the American Standard NDS 2005
- Sustainable Structures Vol.6,No.1,2026 DOI:10.54113/j.sust.2026.000093 Online published:2026-1-2
- Abstract In the elastic field, for beams of rectangular cross-section composed of several vertical layers of materials and linked through horizontally arranged mechanical connectors, it is necessary to know the law of horizontal shear stresses (τ_zx) to determine the cross-section and spacing of such connectors. Currently, there are only two methods to solve the problem without taking into account the finite element method: the Empirical Method, without a theoretical basis, and the Rational Method, based on the NDS 2005, which does not take into account the horizontal shear stresses (τ_zx). According to numerous authors, both methods lead to conservative results in the spacing of mechanical connectors. A novel method, based on a simplified equation, describes the law of horizontal shear stresses (τ_zx) and solves the problem simply and with acceptable accuracy. Two equations catalogued as exact solutions to the stress problem that had never been used for this purpose before have been applied to verify the results. In addition, to validate the new elastic method, information from four-point bending tests performed on specimens of wood beams reinforced with steel plates linked with different connection means, such as bolts, screws, nails and combinations, was used to validate the new elastic method. Fifty-four states were analyzed for flitch beams, varying the magnitude of a uniform load and the span for a simply supported beam. The mechanical connector was adopted as ½ inch for all cases. The Rational and Elastic methods used the NDS 2005 specifications to consider humidity and temperature. The results showed that the spacing of the mechanical connectors according to the Rational Method was conservative since it required a design load perpendicular to the grain. In addition, the New Method made it possible to obtain a larger spacing between mechanical connectors, reducing the number of bolts without affecting the resistance to horizontal shear stresses of the beam. The New Method demonstrated great practical utility and potential to be incorporated into the Allowable Stress Design method of the NDS 2005.… More
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