153 research outputs found
Innovative upscaling of architectural elements for strengthening building structures
For conservation of heritages or life prolongation of aged buildings that contributes to environmental sustainability, there is a global need of structural strengthening or upgrading so as to restore their original functions or fulfil more stringent performance requirements stipulated in modern design codes of practice. However, the actual implementation is usually met with resistance from the property owner; hence, it is desirable to adopt an effective, economical and less invasive technique. In order to provide a further incentive, this article explores an innovative idea of upscaling decorative architectural elements, such as brackets, knee braces and corbels, in order that they also possess adequate strength capacity to resist extreme loadings such as earthquake actions. The required dimensions of architectural brackets for seismic retrofitting of concrete beam-column joints are calculated for different levels of seismicity through a parametric study. It is demonstrated that the proposed design can enhance both the aesthetics and structural performance of a building. This exemplifies how art can be integrated into engineering design for solving real-world problems.</p
Analytical design models for geotechnical seismic isolation systems
Geotechnical Seismic Isolation (GSI) can be defined as a new category of seismic isolation techniques that involve the dynamic interaction between the structural system and geo-materials. Whilst the mechanism of various GSI systems and their performance have already been demonstrated through different research methods, there is a missing link between fundamental research and engineering practice. This paper aims to initiate the development in this direction. A new suite of equivalent-linear foundation stiffness and damping models under the same framework is proposed for four GSI configurations, one of which is a novel combination of two existing ones. The exact solutions for the equivalent dynamic properties of flexible-base systems have also been derived that explicitly include the foundation inertia and the strain-dependent equivalent damping of foundation materials, which are both significant for GSI systems. The application of the proposed analytical design models has been illustrated through response history analyses and a detailed hand-calculation design procedure has also been outlined and demonstrated.</p
Analytical design models for geotechnical seismic isolation systems
Geotechnical Seismic Isolation (GSI) can be defined as a new category of seismic isolation techniques that involve the dynamic interaction between the structural system and geo-materials. Whilst the mechanism of various GSI systems and their performance have already been demonstrated through different research methods, there is a missing link between fundamental research and engineering practice. This paper aims to initiate the development in this direction. A new suite of equivalent-linear foundation stiffness and damping models under the same framework is proposed for four GSI configurations, one of which is a novel combination of two existing ones. The exact solutions for the equivalent dynamic properties of flexible-base systems have also been derived that explicitly include the foundation inertia and the strain-dependent equivalent damping of foundation materials, which are both significant for GSI systems. The application of the proposed analytical design models has been illustrated through response history analyses and a detailed hand-calculation design procedure has also been outlined and demonstrated.</p
Significance of post-shaking response of SDOF systems
The present study reveals for the first time that some real earthquake ground motions would induce the absolute maximum response (AMR) of structural systems posterior to the end of the excitation. Under these ground motions, illustrated using single-degree-of-freedom (SDOF) systems, the peak responses calculated within the during-shaking phase might be significantly lower than the actual AMR. Extending the dynamic analysis to the post-shaking phase by half of the structural period is recommended when conducting response history analyses or calculating the response spectra of these ground motions.</p
Characteristics of earthquake ground motions requiring extended dynamic analysis
The absolute maximum response (AMR) of structures might occur posterior to the end of earthquake excitations, hence, extending the dynamic analysis to the post-shaking phase is required. This phenomenon was found to be more common for long-period and low-damping structures, which are prevailing in regions of low-to-moderate seismicity like Australia. In this article, the mechanism of the occurrence of AMR in the post-shaking phase is first explained using single-degree-of-freedom (SDOF) systems subjected to a simple sine wave. Further investigation on real earthquake ground motions reveals that whether an extended analysis is required depends greatly on the characteristics of the post-significant duration phase. Finally, suitable metrics for describing ground motions that require extended analysis (EAGMs) are identified based on the Kolmogorov–Smirnov test. Regression analyses are then conducted to predict the probability of EAGMs.</p
Significance of post-shaking response of SDOF systems
The present study reveals for the first time that some real earthquake ground motions would induce the absolute maximum response (AMR) of structural systems posterior to the end of the excitation. Under these ground motions, illustrated using single-degree-of-freedom (SDOF) systems, the peak responses calculated within the during-shaking phase might be significantly lower than the actual AMR. Extending the dynamic analysis to the post-shaking phase by half of the structural period is recommended when conducting response history analyses or calculating the response spectra of these ground motions.</p
Characteristics of earthquake ground motions requiring extended dynamic analysis
The absolute maximum response (AMR) of structures might occur posterior to the end of earthquake excitations, hence, extending the dynamic analysis to the post-shaking phase is required. This phenomenon was found to be more common for long-period and low-damping structures, which are prevailing in regions of low-to-moderate seismicity like Australia. In this article, the mechanism of the occurrence of AMR in the post-shaking phase is first explained using single-degree-of-freedom (SDOF) systems subjected to a simple sine wave. Further investigation on real earthquake ground motions reveals that whether an extended analysis is required depends greatly on the characteristics of the post-significant duration phase. Finally, suitable metrics for describing ground motions that require extended analysis (EAGMs) are identified based on the Kolmogorov–Smirnov test. Regression analyses are then conducted to predict the probability of EAGMs.</p
Dynamic leaching assessment of recycled polyurethane-coated tire rubber for sustainable engineering applications
Assessing the material ramifications of waste tire rubber stands as a pivotal endeavor for its practical utility. Dynamic leaching analysis emerges as indispensable in delineating its potentialities within sustainable engineering domains. Waste materials stemming from tire recycling industries, notably polyurethane-coated rubber (PUcR), may exhibit promising viability owing to attenuated leaching, thus fostering the circular economy paradigm. Towards this end, upflow column percolation leaching tests were conducted on recycled rubber-soil mixture (RSM) alongside PU-coated rubber-soil mixture (PUcRSM). Analysis through Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) unveiled the leaching dynamics of assorted metals in RSM and PUcRSM, notably showcasing markedly diminished cumulative zinc content (by 99.4%) in PUcRSM, coupled with mitigated electrical conductivity, redox potential, and eluate pH. Leveraging HYDRUS-1D for analytical modeling predicated on the advection-dispersion equation further underscored these insights. These findings suggest that waste PUcR presents itself as a viable option, distinguished by its diminished leachability, suitable for a wide array of applications. These applications include vibration damping in infrastructure, tunnel linings, asphalt roads, rubberized concrete, and lightweight backfill materials for bridges and retaining walls, among others. This initiative will contribute to recycling a substantial quantity of over 1 billion used tires produced annually, ultimately supporting the circular economy ethos through assured and adaptable repurposing of waste from tire rubber recycling industries.</p
Dynamic properties of recycled polyurethane-coated rubber-soil mixtures
A large quantity of end-of-life tire (ELT) rubber is being blended with thermoplastic polyurethane to provide a durable and ecologically friendly material for flexible surfaces, while a significant quantity of thermoplastic elastomeric waste (left-over and cut-outs) is also generated. These waste materials can be used efficiently for seismic isolation and vibration damping at a minimal cost, a process known as frugal innovation. In this regard, waste thermoplastic elastomeric (TPE) material, which is also known as polyurethane-coated rubber (PUcR), obtained from the tire rubber recycling industry, is explored in this study. Herein, we targeted to evaluate the stiffness and energy dissipation capabilities of waste TPE or PU-coated rubber, which, to the best of our knowledge, has never been reported before. To that end, a series of cyclic triaxial tests were carried out on PU-coated rubber-soil mixtures. In comparison to untreated rubber-soil mixtures, the shear modulus of PU-coated rubber-soil mixtures reduces by 5.5–12.7%, while the damping ratio increases by up to 12.6%.</p
- …