The microstructure of compacted sand–bentonite mixtures (SBMs) modified with sugarcane bagasse ash (SBA) was investigated to evaluate the mechanisms responsible for improving their suitability as sustainable landfill liner materials. SBA was incorporated at replacement levels of 0%, 2.5%, 5%, 7.5%, 10%, and 12.5%, while the mixtures were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and X-ray Diffraction (XRD). XRD analysis of the control sand revealed quartz, kaolinite, and metahalloysite as the dominant mineral phases, with minor quantities of gibbsite and vermiculite. The mixture containing 10% bentonite and 12.5% SBA exhibited new diffraction peaks and peak broadening, indicating the formation of calcium silicate hydrate (C–S–H) and confirming the occurrence of pozzolanic reactions. SEM images demonstrated a progressive transformation from the loose, porous granular structure of the untreated sand to a dense, compact, and well-cemented matrix in the SBA-modified mixtures. EDX analysis of the optimum mixture recorded oxygen (61.40 wt%), silicon (17.37 wt%), aluminum (6.52 wt%), and iron (6.42 wt%), confirming the development of a silica–alumina-rich cementitious matrix. These microstructural modifications enhanced particle bonding, reduced pore spaces, and improved contaminant retention capacity. The findings demonstrate that SBA effectively induces pozzolanic reactions and pore refinement, making SBA-modified SBMs a sustainable and environmentally friendly material for engineered landfill liner systems.
To evaluate the interference level of dynamic stray currents from urban rail transit on adjacent buried steel gas pipelines, this paper establishes a two-dimensional resistive network model of subway-soil-pipeline-earth based on bilateral power supply and bidirectional train operation conditions. First, the soil distribution resistance parameters in the track-to-pipeline zone were determined. Second, this model was used to investigate the influence patterns of track resistance, drainage network resistance, train operating position, train interval, and traction substation grounding mode on the pipe-to-ground potential. The model's validity was verified using actual potential monitoring data from gas pipelines adjacent to subway lines. Results indicate that when track resistance increases to 10 times the standard limit (0.01 Ω/km), the maximum positive/negative pipe-to-ground potential deviation rises by approximately 0.4 V. Higher drainage network resistance reduces its ability to collect stray current. When trains pass 500 m and 1500 m away, the maximum positive pipe potential deviation reaches 0.422 V. Different departure intervals for up and down trains cause superposition and cancellation effects in potential waveforms. Interference is minimal during simultaneous departures, peaking at 90 s intervals. Among traction substation grounding configurations, floating grounding causes the least pipeline interference, followed by bilateral direct grounding, with unilateral direct grounding causing the most severe interference. Field measurement data closely aligns with simulation results and consistent trends, validating the model's effectiveness. This study guides the prediction of stray current interference and optimizes the pipeline protection scheme design.
This study examines the effects of super-heavy (SHL) vehicles on semi-rigid flexible pavements using various pavement design methodologies. At present, no standardised framework exists for the design of semi-rigid flexible pavements subjected to SHL movements. Current practice commonly relies on performance models originally developed for conventional heavy vehicles; however, the applicability of these models to SHL conditions remains questionable and may result in significant underestimation of pavement damage. In this study, critical pavement responses are simulated mechanistically using the commercially available Mechanistic-Empirical pavement design software HIPAVE, following a benchmarking process against the FAARFIELD program. A hybrid set of pavement materials failure criteria is incorporated into the HIPAVE to simulate pavement responses under SHL operations. The simulation results obtained from HIPAVE show good agreement with those generated by FAARFIELD, demonstrating a reliability of the adopted modelling approach. Furthermore, a novel approach based on the concept of a representative SHL nucleus is proposed to characterise super-heavy loading configurations, enabling efficient assessment of pavement impacts while significantly reducing computational time. The findings from the literature review and numerical analyses indicate that further research is required to establish unified design guidelines and long-term field monitoring including the development of a simplified design chart or nomograph for semi-rigid flexible pavements subjected to SHL movements.
This study investigates the structural behavior of reinforced concrete cantilever retaining walls incorporating shear keys under static loading conditions using three-dimensional finite element analysis in ANSYS Workbench. The primary objective was to evaluate the influence of shear key provision on stability parameters such as sliding resistance, deformation, strain distribution, and stress concentration. A retaining wall of 4.0 m height and 2.4 m base width was modeled under active earth pressure of 48 kN calculated using Rankine’s theory. The baseline model without a shear key was found to be safe against overturning (Factor of safety = 2.97) but unsafe against sliding (FS = 1.26 < 1.5). Finite element results showed maximum equivalent strain of 0.04032 mm/mm, deformation of 5.7 mm, normal stress of 2.4 × 10⁷ Pa, and shear stress of 8 × 10⁶ Pa. The introduction of a shear key significantly improved performance, reducing strain to 0.00488 mm/mm and deformation to 4.2 mm. Further enhancement with bolted shear key configuration yielded the lowest strain (0.003629 mm/mm), deformation (3.8 mm), normal stress (1.15 × 10⁷ Pa), and shear stress (1.5 × 10⁶ Pa). The findings confirm that shear key incorporation effectively enhances sliding resistance, improves stress redistribution, and increases overall structural stability, providing a safer and more economical retaining wall design solution.
In this study, under a fixed RJB distance given by the EXSIM model, we systematically analyze the correspondence between the finite-fault model (EXSIM) and the equivalent point-source model (SMSIM) in ground motion simulations. Based on regional parameters from California, simulations are conducted for four moment magnitudes ranging from Mw 6.0 to 7.5. Through the equivalent distance model and the method of minimizing spectral residuals, the SMSIM parameters that achieve the best match in response spectra between the two types of models are determined. The results show that under the same set Joyner–Boore distance (RJB), the equivalent RJB value corresponding to the SMSIM simulation that best matches the EXSIM results is not necessarily equal to the RJB value set in EXSIM, especially in the near field where a systematic shift is observed. More importantly, in the near-field region, to match the finite-fault effects of EXSIM using SMSIM, the equivalent depth h obtained is significantly greater than the actual set source depth. This phenomenon indicates that within the point-source framework, to equivalently represent near-field saturation effects and the influence of finite fault spatial extension, an “equivalent depth” larger than the true physical depth must be introduced as compensation. This study quantitatively reveals two key patterns: “equivalent RJB shift” and “equivalent h enhancement,” establishing a parametric matching relationship from the far field to the near field. It provides important conversion criteria and physical insights for the engineering-equivalent application of finite-fault and point-source models in ground motion simulation.
Shear connectors play a vital role in facilitating composite action between the supporting steel beam and concrete slab. This paper explores rebar shear connectors' strength and failure behaviour within solid concrete slabs. The developed finite element model accurately predicted the ultimate shear capacity with the experiment. The average ratio of numerical to experimental predicted load capacity was 1.0 (ranging from 0.76 to 1.2). The FE model was capable of predicting similar failure behaviour observed during experiment. Additionally, the validated FE model was employed to conduct an extensive parametric study. The influence of both rebar strength and concrete grade on the shear performance of rebar connectors with diameters of 16, 20, 25 and 32 mm was evaluated through a detailed parametric analysis. This investigation incorporated concrete strengths of 30, 40 and 50 MPa to assess their impact on connector behaviour. Additionally, the connector strength was varied among 275, 415 and 500 MPa. Higher strength bars exhibit better ductile behaviour compared to lower strength bars. Increasing the concrete compressive strength from 30 to 50 MPa led to an approximate 40% enhancement in the shear capacity of 25 mm diameter rebar connectors with a yield strength of 500 MPa. The effect of increased concrete strength was more pronounced in larger diameter rebars with higher yield strength, which showed greater gains in shear resistance compared to smaller diameter connectors with lower-grade steel. Drawing from the results of 33 parametric push-out simulations, a modified design equation, derived from the AISC 360-16 formulation for headed stud connectors is proposed to estimate the ultimate shear strength of rebar shear connectors embedded within solid concrete slabs.
Property taxation is widely recognized as a stable and efficient source of local government revenue and a critical instrument for strengthening fiscal decentralization. In Nepal, the transition to federalism under the 2015 Constitution of Nepal has expanded the fiscal authority of local governments, including the power to levy property taxes. Despite this constitutional mandate and the legal framework established by the 2017 Local Government Operation Act, property tax revenue remains substantially below its potential. This study critically examines institutional constraints, prevailing valuation practices, and reform prospects for property taxation in Nepal. Adopting a qualitative doctrinal and institutional analysis approach, the study reviews constitutional provisions, fiscal legislation, Local Government Economic Acts, government reports, and relevant academic literature. The findings reveal three interrelated challenges: institutional fragmentation between land administration and local governments; reliance on administratively determined minimum land values disconnected from market realities; and limited digital integration of cadastral and tax information systems. These weaknesses undermine revenue productivity and administrative efficiency. The study argues that effective reform requires legal harmonization, adoption of market-based mass appraisal systems, digital interoperability between land and tax databases, and enhanced technical capacity at the local government level.
Damping is a measure of energy dissipation, and while coupling beams contribute to this through yielding and nonlinear behaviour, conventional structural design software does not assign a specific damping ratio to these members. Reinforced Concrete coupling beams protect the shear walls or cores by absorbing and dissipating seismic energy through cracking and rotation, making their damping estimation crucial in lateral design. This technical note introduces two complementary power-law models for estimating damping in Reinforced Concrete coupling beams subjected to the deemed effects of cyclic loading. The first model relates damping (D) to stress amplitude (σₐ), and the second model expresses D as a function of plastic hinge rotation (θ). Both models are rooted in Khanna’s earlier ICE (Institution of Civil Engineers-1976) work and are demonstrated using a 20-storey structural example. To enhance practical relevance, the methodology employs an equivalent static approach, avoiding full time-history or Finite Element Method (FEM) -based hysteretic modelling. The note also introduces the role of soil–structure interaction (SSI) and compares damping predictions from both models across elastic, cracked, and yielded states. Normalized design curves and manual worked examples illustrate that the stress amplitude model is more responsive to early-stage material cracking, while the rotation-based model reflects overall deformation. This combined framework offers structural designers a transparent, physics-based guide to assessing damping in coupling beams and is useful for performance-based seismic design, retrofit evaluation, and simulation benchmarking. This technical note presents two complementary power-law models for quantifying damping behavior in reinforced concrete (RC) coupling beams under cyclic loading. The first model relates damping (D) to stress amplitude (σₐ), while the second relates damping (D) to plastic hinge rotation (θ). Together, they offer a practical framework for estimating hysteretic damping without full-scale Finite Elelement Method (FEM) analysis. The note also introduces the role of soil–structure interaction (SSI) and compares damping predictions from both models across elastic, cracked, and yielded states. Normalized design curves and manual worked examples illustrate that the stress amplitude model is more responsive to early-stage material cracking, while the rotation-based model reflects overall deformation. This combined framework offers structural designers a transparent, physics-based guide to assessing damping in coupling beams and is useful for performance-based seismic design, retrofit evaluation, and simulation benchmarking.
The essence of enduring architecture lies in harmony between form and structure. Throughout history, the most successful architectural works derived their beauty, economy, and permanence from structural truth, where geometry evolved naturally from the flow of forces. In much of contemporary parametric and sculptural architecture, however, visual fluidity and formal abstraction often precede and dominate structural reasoning. This paper examines how unconventional architectural forms may conflict with the natural regime of load transfer and equilibrium, compelling engineers to introduce concealed supports, redundant framing systems, and artificial load paths to stabilize geometries that do not inherently follow structural logic. The resulting condition is compared metaphorically to “a knot in a straight thread,” where continuity of force flow is interrupted despite apparent external elegance. The discussion further highlights how asymmetric massing and irregular geometries under seismic and wind excitation can induce torsional amplification, phase drift, and dynamic instability, potentially leading to progressive deformation and localized structural distress. At the same time, the paper demonstrates that unconventional geometry need not oppose structural principles. Forms such as the hyperbolic paraboloid exemplify how abstract architecture can still embody structural efficiency through membrane action, anticlastic curvature, and continuity of load paths. Drawing upon examples from contemporary architecture and structural philosophy, the paper argues that true architectural freedom emerges not from defying structural principles, but from integrating imagination with equilibrium, material behaviour, and force flow. It concludes that lasting architectural beauty is achieved when form and structure coexist in natural harmony rather than in opposition.
More than four decades ago, a double-slab reinforced concrete foundation concept for large-diameter steel storage tanks incorporating orthogonal slits in the bottom slab was proposed but not adopted because of concerns regarding structural continuity and seismic performance. With advances in finite element modelling and soil–structure interaction analysis, the structural behaviour of such an articulated foundation system can now be re-examined. This study compares two foundation configurations: (A) a conventional monolithic double-slab foundation and (B) a slitted configuration in which full-depth orthogonal slits are introduced in the bottom slab and connected through shear dowels. Three-dimensional finite element models are developed using solid elements to represent the concrete components and Winkler-type elastic springs to simulate soil support. The analysed system represents a 58 m diameter storage tank foundation subjected to a uniform pressure load of 150 kPa together with a horizontal seismic acceleration of 0.25 g. The complete structural system is modelled as one combined unit and analysed. The results indicate that the slitted configuration reduces peak soil contact pressure from approximately 210 kPa to 185 kPa, resulting in a more uniform pressure distribution under static loading. However, the associated reduction in global stiffness increases vertical deflection from 18.2 mm to 19.1 mm under static load and from 23.75 mm to 25mm under seismic loading. Stress concentrations are also observed near slit–dowel interfaces under seismic excitation. The findings demonstrate that controlled articulation of foundation slabs can modify load-transfer mechanisms and soil pressure behaviour, although its application requires careful detailing and consideration of seismic effects. The study provides analytical insight into articulated tank foundation systems and establishes a rational framework for evaluating such configurations within performance-based foundation design.
The construction industry plays a significant role in economic development, infrastructure delivery, and social transformation, while simultaneously contributing to environmental degradation and resource depletion. Consequently, the sector is increasingly recognised as a critical stakeholder in achieving the United Nations Sustainable Development Goals (SDGs). This study evaluates the contribution of construction organisations in Ghana toward achieving the SDGs using Exploratory Factor Analysis (EFA) and Fuzzy Synthetic Evaluation Modelling (FSEM). A quantitative research design was adopted, and data were collected through a structured questionnaire administered to registered building and road contractors. Out of 357 distributed questionnaires, 250 valid responses were obtained and analysed. The findings identified five major dimensions of SDG-related activities undertaken by construction firms: Infrastructure Restoration, Health and Well-being, Social Development, Human Development, and Sports Development. The results revealed that construction organisations contribute to SDGs through activities such as sanitation support, school renovation, health screening, scholarship schemes, skills training, and community infrastructure provision. Human Development recorded the highest fuzzy index value, while Sports Development ranked lowest. However, all dimensions recorded index values below 3.0, indicating that sustainability-related activities are undertaken infrequently. The study concludes that although construction firms contribute to sustainable development, their engagement remains limited and insufficiently integrated into organisational strategies. The research contributes to sustainable construction literature by providing empirical evidence from a developing-country context and demonstrating the applicability of fuzzy synthetic evaluation in assessing SDG-related performance under uncertainty. The study recommends stronger regulatory enforcement, improved sustainability reporting frameworks, and greater integration of sustainability principles into construction practices.
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.
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.
Slope instability is a common problem in mountainous road corridors, particularly in regions characterized by steep terrain, weak soil formations, and intense seasonal rainfall. The Bonga-Felegeselam road in southwestern Ethiopia has experienced several slope failures during construction due to these unfavorable geological and hydrological conditions. This study investigates the causes of instability and evaluates appropriate stabilization measures for two critical cut slopes located between Stations 16+900 to 16+980 (left-hand side, LHS) and Stations 35+200 to 35+300 (both LHS and RHS) of LOT I: Bonga Asphalt Road Project. Detailed site characterization was conducted through field observations, geometric configuration, soil classification, and laboratory testing to determine the relevant geotechnical properties. Slope stability was assessed using both deterministic and probabilistic approaches based on the Limit Equilibrium Method (LEM) and the Finite Element Method (FEM). The analyses considered different groundwater conditions to evaluate the influence of rainfall-induced saturation on slope stability. The results indicate that the slopes become highly unstable under fully saturated conditions, with factors of safety ranging from 0.657 to 0.916 and failure probabilities between 41.8% and 95.3%. Sensitivity analysis further showed that slope stability is more sensitive to variations in the friction angle than cohesion. To mitigate the instability, a combination of masonry retaining walls, surface drainage, and subsurface drainage systems was proposed. Post-remediation analyses demonstrated a significant improvement in slope stability, increasing the factor of safety to values between 1.57 and 1.90. The findings highlight the importance of integrating deterministic and probabilistic approaches to develop reliable stabilization strategies for rainfall-prone mountainous regions.
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.
Seismic performance evaluation of high-rise buildings plays a crucial role in maintaining structural safety within earthquake-prone regions. The growing frequency and intensity of seismic activities worldwide require innovative approaches to structural design that focus on resilience, creating sustainable solutions and safety assurance. The conventional force-based methods fail to properly capture nonlinear structural behaviors. On the other hand, energy-based seismic analysis provides a better understanding of how seismic energy get absorbed and distributed within buildings that is to say, the pathways through which earthquake energy flows. This study analyzes the behavior of a 10-story reinforced concrete (RC) building using pushover analysis (POA) and response spectrum analysis (RSA) in ETABS, following the Bangladesh National Building Code (BNBC 2020). The building is modeled with typical gravity and lateral load-resisting systems, considering BNBC seismic code specifications. The POA provides insights into the nonlinear performance of the structure, identifying hinge locations and performance levels under increasing lateral loads. Meanwhile, RSA assesses building responses to seismic motions through vibration pattern studies. A comparative evaluation of base shear, story displacement and drift ratios is conducted to determine whether the structure meets BNBC safety limits. Results suggest that while response spectrum analysis is effective for preliminary design, pushover analysis offers deeper insight into potential failure mechanisms. This study emphasizes the significance of integrating both static and dynamic approaches for a comprehensive seismic evaluation of high-rise buildings.
Rapid urbanization and population growth in Bangladeshi cities, Barisal in particular, have created serious environmental issues including urban water-logging. While flooding prevents the infiltration of rainwater, the extensive concreting of the open space, the boulevards, and waterbodies have become a barrier to rainwater infiltration and flooding the daily life, the infrastructure, and the contamination of water. Therefore, there is a need for stormwater management. This study examines permeable pavement systems (PPS) systems as a potentially sustainable model. PPS systems recharge groundwater, manage surface runoff, and reduce flooding in residential, commercial, and industrial areas. The hydraulic modeling revealed that a 35-inch-deep PPS system with underdrain capabilities can hold approximately 865.41 cubic feet of stormwater. The study concluded that permeable pavement systems provide a sustainable long-term solution for stormwater management when conventional drainage isn't able to manage stormwater sufficiently. This is one mere action toward achieving Sustainable Development Goal 11 towards sustainable Cities and human. Thus, this study provides the foundation for urban sustainability, resilience, public health, environmental protection, and infrastructure sustainability and durability. A PPS system will provide immediate benefits to be achieved, however over time the long-lasting benefits will build stakeholder involvement from the community at large.
Tall steel buildings are increasingly governed by serviceability considerations arising from seismic and wind actions, where control of lateral deflection and inter-storey drift becomes as critical as strength-based design. This paper investigates the fundamental relationship between lateral stiffness and deflection response in tall steel structures, with the objective of clarifying the role of stiffness in satisfying codal requirements for safety, serviceability, and occupant comfort. A common misconception in design practice is that increased structural flexibility invariably leads to reduced seismic demand. While period elongation associated with reduced stiffness may lower seismic base shear, it can result in excessive lateral deflections, inter-storey drifts, and wind-induced accelerations that govern serviceability performance. Using a shear-building idealisation, closed-form analytical relationships are developed to link effective lateral stiffness, fundamental natural period, inter-storey drift, and seismic base shear. Three representative lateral load-resisting systems-a steel moment-resisting frame (SMRF), a braced frame (BRBF), and a core-outrigger system-are evaluated for a 20-storey steel building to illustrate the influence of stiffness on global and local response parameters. The comparative results demonstrate that increased stiffness leads to improved drift control and wind-serviceability performance, even where seismic base shear increases modestly. A worked example is presented to demonstrate drift verification against Eurocode seismic serviceability limits and wind habitability criteria, showing that serviceability requirements often govern system selection in tall buildings. The study provides practical guidance on balancing stiffness, damping, and structural configuration during preliminary design. The proposed analytical framework supports rational comparison of alternative lateral systems and offers useful insights for engineers prior to undertaking detailed numerical analysis.
This study investigated the potential of utilizing Waste Plastic Bottles (WPB) as a sustainable modifier in asphalt pavement mixtures, systematically examining the characteristics of aggregates, the WPB-modified bitumen binder, and the resulting asphaltic concrete mix. Detailed analysis of the aggregate gradation revealed the coarse fraction to be a well-graded gravel, characterized by a uniformity coefficient (Cu) of 2.47 and coefficient of curvature (Cc) of 1.14, indicative of optimal packing density for structural stability. These aggregates exhibited high durability, with an Aggregate Crushing Value (ACV) of 18.3% and Aggregate Impact Value (AIV) of 16.9%, ensuring resistance to abrasion and impact under traffic loads. In contrast, the fine aggregate was poorly graded (Cc = 0.45), highlighting the need for binder modification to enhance overall mix cohesion. Modification of pure bitumen (initial penetration 69 mm) with WPB progressively induced desirable hardening effects and superior high-temperature performance. Penetration values decreased markedly from 69 mm to 33 mm at 25% WPB incorporation, while the softening point rose substantially from 52°C to 81°C, demonstrating enhanced rutting resistance and thermal stability critical for tropical climates like Nigeria's Lagos region. Additional rheological improvements included increased viscosity (up to 2984 p.a.s), flash point (289°C), and specific gravity (1.13), with minimal ductility loss, collectively affirming WPB's role in creating a more resilient binder. Marshall performance testing on the WPB-modified asphaltic concrete further validated these enhancements. The mixture achieved maximum Marshall Stability of 19.74 kN and peak Marshall Quotient of 4.32 kN/mm at 15% WPB content— a 78% stability increase and 34% quotient gain over the control mix (11.05 kN and 3.22 kN/mm). Flow values remained controlled (3.43–4.57 mm), balancing stiffness with workability. These outcomes, aligned with prior pelletized WPB concrete data showing optimal 10–15% thresholds, confirm WPB's efficacy in boosting stiffness, load-bearing capacity, and deformation resistance. Overall, WPB modification yields a mechanically superior, eco-friendly alternative to conventional asphalt, promoting waste valorization while meeting geotechnical standards for durable pavements in sustainable infrastructure projects.
Decarbonisation of heavy vehicles to achieve net-zero greenhouse gas emissions, through the adoption of Zero-Emission Heavy Vehicle (ZEHV) technologies, inevitably influences vehicle typology and axle mass distribution. The additional weight of batteries used in ZEHV systems must be accommodated within existing vehicle mass limits. In Australia, the freight industry is advocating for a minimum one tonne increase in the allowable steer axle load to facilitate greater uptake of electric heavy vehicles. This desktop review investigates the potential effects of a one tonne increase in steer axle load on flexible pavements of both local roads and rural national highways. Currently, there is no nationally standardised methodology for assessing unacceptable pavement wear. This study compares several approaches and concludes that the use of mechanistic-empirical method with weigh-in-motion (WIM) data provides a more accurate assessment of pavement wear than analyses based solely on individual vehicle axles or total vehicle axle loads. The pavement wear analysis indicates that the steer axle contributes the greatest cumulative distress across all pavement types examined. Furthermore, the results show that a one-tonne increase in steer axle load would have a substantially greater impact on local roads- leading to an estimated 31.3% to 48.7% reduction in pavement life- compared with a 20.9% reduction in rural national highways.
