Performance Of Infrastructure Research Articles

Synthesis of physical processes of permafrost degradation and geophysical and geomechanical properties of permafrost

Recent permafrost degradation across the high northern latitude regions has impacted the performance of the civil infrastructure. This study summarizes the current state of physical processes of permafrost degradation in a geotechnical context and the properties of permafrost-affected soils critical for evaluating the performance of infrastructures commonly built in the high northern latitude regions. We collected a total of 96 datasets with 3162 data points from 38 journal and conference publications and analyzed the variations of geomechanical and geophysical properties under the effects of permafrost degradation. The datasets represent a range of geomechanical and geophysical properties of permafrost-affected soils with different compositions under different testing conditions. While the data collected are highly scattered, regression analysis shows that most geomechanical and geophysical properties have strong associations with temperature. These associations highlight that ongoing warming can greatly affect the performance of civil infrastructures at high northern latitudes. These properties include elastic moduli, strength parameters, thermal conductivity, heat capacity, unfrozen water content, and hydraulic conductivity. This paper also discusses other factors, such as soil type, soil composition, and confining pressure, which may further complicate the relationships between temperature and the geomechanical and geophysical properties. Through this review, we identify key knowledge gaps and highlight the complex interplay of permafrost degradation, temperature, soil heterogeneity, and soil geomechanical and geophysical properties. Given the scarcity of certain permafrost properties in addition to the complex processes of permafrost degradation in the geotechnical context, there is a need to establish a comprehensive and curated database of permafrost properties. Hence, we encourage broader collaboration and participation by the engineering and scientific communities in this effort.

The “price” of saved time, the illusion of saved fuel: Life-Cycle Assessment of a major highway expansion

The road transport sector is a major responsible for pollutant greenhouse emissions. Airborne and other types of environmental impacts involve much more than just the most addressed driving activity and its combustion residues. Building upon a previous work rooted in systems thinking and emergy accounting, Life-Cycle Assessment is applied to transport studies in order to evaluate the environmental performances of a civil infrastructure in Italy before and after major expansion and deviation works: altogether, these methods are used as comprehensive tools to measure sustainability, while including resource consumption and requirements, direct and indirect environmental impacts, and their effects on human health, all depicted by a wide selection of 30 standard indicators. The expansion project, completed in recent years, is compared with the no-build option as well as with the results from the previous cost-benefit and emergy-based systemic assessments, thus shedding novel light on road construction and appraisal compared to purely economic and purely ecological tools only. Life-Cycle Impact Assessment results are expressed in terms of impact indicators per full highway section, but results per road length unit (km), and per transport service unit (p-km and t-km) can be derived. Unlike the claims by managing authority and policy-makers, an overall worsening is found in all of the adopted environmental indicators, although differences exist among them (from +47% up to +244%, with most indicators doubling or even tripling after the renovation works). Expected on-road fuel savings, where applicable, just mitigate an overall negative situation: such savings are overcome by the effects of the fuels indirectly required to obtain them, and by the overall impacts following the expansion, albeit normalised through relevant amortisation. The only stable saving, i.e. travel time, stays structurally out of a Life-Cycle Assessment, whose clear results can serve as a basis for possibly long-sighted design, planning, and decision-making in an era of urgently needed environmental actions.

The Effect of Motivation, Work Environment, and Infrastructure on Teacher Performance in SMK Negeri 1 Kutacane

This study aims to determine the effect of motivation, work environment, and infrastructure on teacher performance simultaneously or partially. The research also aims to obtain an effective policy formulation as an improvement/improvement of teacher performance at SMK Negeri 1 Kutacane. The sample in this study amounted to 82 teachers. This type of research is descriptive quantitative. Data was collected by distributing questionnaires directly to teachers and secondary data. The data analysis technique used is the instrument test, namely the validity test and the reliability test as well as the analytical method consisting of the t test, f test, and data analysis using multiple linear regression models. The results of the study indicate that motivation, work environment, and infrastructure significantly positively affect teacher performance simultaneously. Partially, motivation and environment significantly affect teacher performance, while infrastructure partially has no significant effect on teacher performance. These results show that if the motivation, work environment, and infrastructure are improved together, it will further improve the performance of teachers at SMK Negeri 1 Kutacane. Keywords: Motivation, Work Environment, Infrastructure, and Teacher Performance.

Polyurethane grouting materials with different compositions for the treatment of mud pumping in ballastless track subgrade beds: properties and application effect

Mud pumping in subgrade beds under ballastless tracks will deteriorate the dynamic performance of infrastructure under railway lines, reduce the smoothness of the railway lines, and seriously affect the comfort and safety of the trains. Due to their good mechanical properties, two-component polyurethane materials can be used for grouting to treat the fouling problems caused by ballastless track mud pumping. To develop a polyurethane formula suitable for the treatment of ballastless track mud pumping, we first performed indoor experiments to investigate the mechanical properties and gelation time of polyurethane elastomers synthesized with different raw material composition ratios, to determine an optimal composition ratio of the raw materials. Then, we conducted a dynamic field test to verify the remediation effect of the polyurethane material fabricated according to the design ratio. The results showed that polyurethane grouting material with the selected design ratios improved the contact characteristics between the surface layer of the subgrade bed and the base plate in the area, coordinating the dynamic response between the track structure and the subgrade bed. Thus, the obtained polyurethane grouting material could be used to renovate mud pumping areas of ballastless tracks with a good treatment effect.

NEGATIVE IMPACTS FROM DISRUPTION OF ROAD INFRASTRUCTURE ELEMENT PERFORMANCE ON DEPENDENT SUBSYSTEMS: METHODOLOGICAL FRAMEWORK

The critical infrastructure system is determined by subsystems essential for the functioning of the state (such as energy, transport, and emergency services). Disruption to the function of these subsystems would have serious effects on state security, the state economy, and the provisioning of the inhabitants’ basic human needs. Links connect these subsystems (i.e., sectors, subsectors, and elements), and these links ensure that certain subsystems are integrated into each other. Their interactions are derived from the type and intensity of the mutual link. The interlinked subsystems can thus be divided into influencing and dependent ones. The aforementioned mutual links in the critical infrastructure system allow, amongst other things, the spread of impacts of disruptive events amongst the subsystems via cascading effects. Disruptions to the performance of an influencing subsystem may have negative effects on a dependent subsystem, resulting in the spread of cascading effects in the critical infrastructure system. Such effects are often difficult to predict, which reduces the responsiveness of the dependent subsystems. Road transport is one of the most significant influences on critical infrastructure subsystems. For this reason, the article focuses on an indication of the negative effects of disruption of road infrastructure elements on dependent subsystems. The article describes the role of road infrastructure in the context of the critical infrastructure system. Defines the dependent subsystems of road infrastructure, categorises the negative effects, and presents a possible approach to assessing the adverse effects of disruption road infrastructure performance on dependent subsystems.

Assessing the Contribution of Innovative Technologies to Sustainable Development for Planning and Decision-Making Processes: A Set of Indicators to Describe the Performance of Sustainable Urban Infrastructures (ISI)

The sustainable development of our cities and regions has become an integral part of the current debate. To achieve the sustainability goals, however, the development of sustainable technologies and infrastructures as well as decisive municipal action at the local level are essential. The research project VertiKKA (“Vertical Air Conditioning and Wastewater Treatment System”), sponsored by the German Ministry of Education and Research, addresses both technology development and the integration of innovative technologies and infrastructures into urban planning and decision-making processes. As a result, a set of indicators was developed that allows the assessment of urban infrastructures and technologies and their contribution to sustainable development. This article presents the “set of indicators for sustainable urban infrastructures” (ISI). ISI is based on the results of literature and policy review but was further developed and tailored to urban infrastructures and technologies. ISI considers the ecological, economic, and social dimension of sustainability to be of equal importance; in addition, ISI places particular emphasis on looking at the technology development process and on the creation of supportive governance structures for implementation. In order to create a link between research and practice, the applicability of ISI to the VertiKKA technology is critically reflected.

Contribution of Infrastructure to the Township’s Sustainable Development in Southwest China

Townships in Southwest China are usually located in mountainous regions, which are abundant in natural and cultural landscape resources. There are additional requirements for the township’s sustainable development in these areas. However, insufficient infrastructures, due to limited resources, constrain the sustainable development of these townships. Sustainable contribution of infrastructure (SCOI) in this study is defined as the performance of infrastructure as a contribution to the coordinated development among economic, social, and environmental dimensions of township’s sustainable development. It is necessary to assess these infrastructures according to SCOI and provide choices for investment to maximize resource utilization. Therefore, an assessing model of SCOI with 26 general indicators was developed, which covers five most urgently needed infrastructures of these townships in Southwest China, including road transport, sewage treatment, waste disposal, water supply, and gas. In this model, quantitative and qualitative methods are combined to acquire different SCOI of each infrastructure. The result of the SCOI would be an important reference for infrastructure investment. A case study of Jiansheng Town, that is located in the Dadukou district of Chongqing, demonstrates the applicability of the model. It shows the assessing model of SCOI is efficient to identify the most valuable infrastructure that is appropriate for investment with the goal of township’s sustainable development. This study can provide insights for infrastructure investment and management in townships or areas.

Relationship between transport infrastructure expenditures and costs and transport indicators - an overview of European and Ukrainian situation

Quality of transport infrastructure determines the quality of the provision of services for the transportation of goods and passengers. The infrastructure sector is a guarantee of efficiency, mobility and uninterrupted economic activity. However, the high quality of the transport infrastructure implies significant and long-term investments. According to a McKinsey research report, to support sustainable economic growth in the world in line with forecasts for 2030, it is necessary to cover the need for additional investment of $ 3.3 trillion annually, equivalent to 3.8% of world GDP. The purpose of this work is to analyze the existing European approach to assessing transport infrastructure expenditures and costs, their impact on transport performance at the country level, as well as trends in Ukrainian policy regarding the support and development of road infrastructure. Transport infrastructure costs include the investment in new infrastructure, the cost of upgrading the existing infrastructure, the cost of maintaining the infrastructure, and the operating costs to enable the use of the transport infrastructure. Directive 2011/76 / EU prescribes that the weighted average infrastructure charges should be linked to construction costs, as well as the costs of operation, maintenance and development of the corresponding infrastructure network. The official Eurostat data of investment and O&M costs of transport infrastructure based on the citizenship principle was taken for this study, namely: - the number of ton-kilometers traveled per year; - the volume of investments in road infrastructure per year; - the amount of funds for the maintenance of road infrastructure per year. The indicators were taken for countries of the EU for which statistics were available for 2016 and 2019. According to the study, the effect of investments in transport infrastructure is strongly manifested both in the same year and affects subsequent years in terms of the volume of annual transport work. That is, an increase in investment in road infrastructure clearly has a positive effect on the volume of transport work performed. On the other hand, the volume of investments in the EU infrastructure brings a much greater positive effect than funds for road maintenance. Thus, the experience of developed countries shows a positive relationship between investment in the maintenance and construction of transport infrastructure and economic performance of the state. Part of the research was devoted to the study of the impact of investments in road infrastructure of Ukraine on the example of the global Ukrainian infrastructure project "Big Construction". It is projected that in 2024, thanks to road works under the Big Construction, Ukraine's GDP will be 4.4% higher than GDP in 2020. But, as the research shows, good transport infrastructure is a necessary, but not a sufficient condition for growth. "Big Construction" project in Ukraine does not show any positive effect on the volume of performed internal transport work now. The reasons may lie both in more long-term effect from improving the infrastructure, and in the facts of corruption and theft of funds allocated for the project.

How the UK government plans to transform infrastructure performance this decade

Delivering transformational outcomes for Britain through infrastructure investment needs a revolution, says Nicholas Yandle of the Infrastructure and Projects Authority. A new roadmap describes what civil engineers should be aiming for and the action required to get there.

Quality assurance for the NHS abdominal aortic aneurysm screening programme in England.

IntroductionThe National Health Service Abdominal Aortic Aneurysm Screening Programme (NAAASP) was introduced in England in 2009 to offer ultrasound screening to men over 65 years, in order to reduce aneurysm-related deaths. This study describes the development of a quality assurance (QA) process and conducts an analysis of the first round of QA visit reports. The aim was to identify themes where local providers can target their efforts for improvement.MethodsForty-one providers were assessed over 4 years using a process of QA visits adapted from previously established screening programmes. A mixture of qualitative and quantitative methods was used to analyse the 41 QA reports, which identified a range of recommendations for providers. The data were coded for key words and assigned to themes. The number of recommendations per visit report was compared with experience of the providers and performance against national screening standards.ResultsA total of 773 recommendations were made, with an average of 19 per QA visit. Around one third of the recommendations were based on governance and leadership standards, with 43.0 per cent of those based around commissioning and accountability. A significant relationship was seen between number of infrastructure recommendations and performance against standards.ConclusionThis review of a QA cycle found that sound infrastructure is key to the success of a local provider.

Infrastructure Service Assessment Model Based on a Service Quality Gap Model—Focused on South Korea

To improve the quality of life (QOL) of the citizen, it is essential to not only to secure a quantitative stock, such as the number or extension of individual infrastructure, but to also understand the perspective of the public on service levels and the demand for infrastructure. In this study, an infrastructure service level assessment model that reflects the demands of citizens is proposed, and the importance and adequacy of infrastructure service indexes for setting priorities and goals for the investment of government funds in infrastructure are verified. The evaluation items used in this model included usability, accessibility, and recovery speed. The infrastructure service level for 12,500 Korean citizens was surveyed using the proposed assessment model, and the results reveal that the satisfaction of citizens with their residences had a significant effect on the QOL improvement, and that the level of infrastructure performance in a residential area significantly affected the satisfaction of citizens with their residences. In addition, the results revealed that the quantitative and qualitative aspects of infrastructure should be simultaneously considered. Lastly, the possible application of this model for the evaluation of the effectiveness of investment for infrastructure improvement is proposed.

Retrofitting techniques of damaged concrete structure for environment concern: A review

Initiation and progression of damages in the concrete systems is the cause of reduction of structural strength and its durability. The significant retrofitting strategies are required to improve the damages and thus, the performance of infrastructures can be enhanced. The damages in the concrete system is due to several factors viz., ingress of alkaline water, wet-dry cycle, sulfate attack, thermal changes, chloride penetration, and freeze–thaw cycle etc. Changes in the shape and size of concrete segments before and after retrofitting decreases the strength of structural systems and consequently, reduced the durability of retrofitted materials. This review paper is motivated on the application of the retrofitting techniques using Fiber Reinforced Polymer (FRP) material for environment concerned. The deterioration of concrete structure and FRP retrofitted materials durability were discussed. The durability aspect of damaged concrete structure retrofitted with FRP materials under alkaline water, wet-dry cycle, freeze–thaw cycle, open cracks, and water immersion were reviewed. The de-bonding of FRP materials have been described to improve the structural integrity. The suitability of various retrofitting techniques were covered. This paper have been included the retrofitting techniques for the improvement of infrastructural facilities and further, the cracks filled rich cement mortar with FRP over that was the key finding. The review paper will facilitate innovative research directions to the industrialist and researchers.

Prosumer in smart grids based on intelligent edge computing: A review on Artificial Intelligence Scheduling Techniques

Smart Grid technology has been considered an attractive research issue due to its efficiency in solving energy demand, storage, and power transmission. The integration of IoT technology in the Smart Grids is a critical way to accelerate the digitization of the power grid and is useful for the efficient performance of the energy grid infrastructure. For efficient real-time data analysis and decision-making, the Internet of Things will incorporate various communication systems seamlessly. To achieve efficient communication between all Internet of Things, devices are expected to use multiple means, including smart sensors, cable and wireless communication. Improved Internet of Things sensor technologies and connectivity could theoretically prevent or minimize the potential to natural disaster transmission lines, improve transmission power capacity and reduce economic losses. A smart grid is a variety of sensors, devices, and data sets that continuously capture high-resolution data equal to individual IoT conditions. A vast amount of data is one of the biggest challenges on the Internet of Things. Edge Computing is trying to process data close to linked sensors to address this problem, where the data is gathered and processed. This paper aims to investigate the edge computing solutions for the smart grid. A comprehensive review of both emerging issues and edge computing in the Smart Grid environment is discussed and explained. There are two primary components to the energy sharing process among Prosumers: information/digital technologies and Artificial Intelligence Scheduling Techniques. Each of them is mentioned in detail to discuss the Prosumer smart Grid. Furthermore, Edge Computing and classifications (cloudlet, Fog computing and Multi-Access) are among the suitable network methods mentioned in this paper. Some techniques and methodologies have been extensively covered to improve reader awareness of the Prosumer smart grid system.

Determinants of water security in smallholder farming systems in South Africa: a review

Attaining water security is critical for enhancing agricultural production in many countries worldwide. In South Africa, water insecurity is one of the factors affecting agricultural production, especially in the smallholder farming sector. The review focused on factors that influence water security in smallholder farming systems in South Africa and also proposed possible solutions to improve the water security status for smallholder farmers. A search of published articles was conducted on Scopus and Google Scholar databases using the keywords water access, water security, water scarcity, smallholder farmers, smallholder agriculture and South Africa. The study identified various factors that contribute to water insecurity for smallholder farmers, including lack of adequate infrastructure, the poor performance of water infrastructure, lack of farmer involvement in water-related management activities and land tenure insecurity. Smallholder farmers also failed to acquire water-use licences. During periods of drought, they were unable to adopt strategies for improving water security. Recommendations include addressing issues related to infrastructure availability, water allocation and distribution, and the capability to operate, manage and maintain the infrastructure. The study also recommends that policy and decision-makers be acknowledged and address the impacts of droughts on water resource availability.

Синергетический эффект в модификации окисленных дорожных битумов различного группового состава

The physico-chemical-rheological properties of the asphalt binder are critical to the long-term performance of the asphalt pavement infrastructure. The objectives of this investigation are to characterize the physico-rheological properties of unmodified pure and polymer-modified bituminous binders using rheological performance tests. The rheological properties of three pure oxidized bitumen, three SBS with sulfur-modified bituminous binders, and three bituminous binders modified with SBS+S+PPA were studied in this work. Various amounts of styrene-butadiene-styrene (SBS), sulfur (S) and polyphosphoric acid (PPA) modifiers were added to the pure binder for this purpose. The tested physical properties of the bituminous binder include traditional penetration and softening temperature. Group composition studies (saturates, aromatics, tars and asphaltenes; SARA) were respectively conducted to quantify the chemical composition and structural properties of pure oxidized bitumen. A dynamic shear rheometer (DSR) was used to evaluate the durability (PG) of virgin, thin film oxidized (RTFO-aged) and pressure vessel (PAV-aged) bitumens. The resistance to rutting and fatigue failure was evaluated using the test for creep recovery after repeated loading (MSCR). A bending beam rheometer (BBR) was used to study the low temperature properties of bituminous binders. All modifiers have been found to improve the high temperature properties of clean asphalt. In addition, these modifiers have not been found to have a significant effect on the low temperature continuous grade of the binders.

Measuring the impact of transport infrastructure endowment on firms’ performances: the case of Italian agrifood sector

Infrastructures play a relevant role in promoting the socio-economic development of a country, region or area. In particular, transport infrastructure endowment is important for the agrifood supply chains, which have some specifics characteristics that contribute to raising the complexity of external logistics. Italy is leader in the agrifood supply chain, but the Italian transport infrastructure endowment is more backward than its main European competitors. Given the need to pursue the resilience of agri-food systems after having experienced several adverse events, such as COVID-19 pandemic or Xylella disease in the Southern Apulia region, the present study aims at estimating the impact of transport infrastructure on the agri-food firm performances. The research was carried out using a composite set of indicators for measuring the regional endowment of transport infrastructures. Results demonstrate a positive relationship between transport infrastructure and firm performance, and strong territorial differences across Italy. Based on the findings, investment in transport infrastructure needs to be sustained in order to enhance growth in many economic sectors, including the agrifood one, which is closely related to food security. Given the significant role played by transport infrastructures towards the firms’ economic performance improvements and the development of regional economies, the present study could represent a useful tool for government, policymakers and managers to activate the proper drivers of transition.

Civil Infrastructure Digital Twins: Multi-Level Knowledge Map, Research Gaps, and Future Directions

Digital Twins (DTs) have received considerable attention as an emerging technology in recent years, which can offer advantages for improving the performance of infrastructures. However, the inherent complexity of infrastructures alongside the nascent nature of digital twins in the Architecture, Engineering, and Construction (AEC) industry hinders the adoption of infrastructure digital twins (IDTs). The lack of common understanding among different stakeholders has been noted as one of the most significant roadblocks to implementing IDTs in practice. This study is a quantitative attempt to address this gap by providing different stakeholders with a multi-layer knowledge map by analyzing 139 identified IDTs in three levels of bibliometric and social network analyses. First, knowledge themes are extracted from the most-frequent journals to provide an overview of IDT knowledge. Second, a combination of co-citation analysis and social network theories illustrated six clusters of IDT knowledge and their relationships. Third, the co-occurrence network of keywords revealed where, why, and what enabling technologies have been employed so far. These findings were synthesized into a three-layer knowledge map to not only illustrate the maturity level and evolution potentials of each layer but also serve as a hierarchical strategic plan recommending future direction to decision-makers, researchers, and practitioners.

Demand forecasting: an alternative approach based on technical indicator Pbands

Research background: Demand forecasting helps companies to anticipate purchases and plan the delivery or production. In order to face this complex problem, many statistical methods, artificial intelligence-based methods, and hybrid methods are currently being developed. However, all these methods have similar problematic issues, including the complexity, long computing time, and the need for high computing performance of the IT infrastructure.
 Purpose of the article: This study aims to verify and evaluate the possibility of using Google Trends data for poetry book demand forecasting and compare the results of the application of the statistical methods, neural networks, and a hybrid model versus the alternative possibility of using technical analysis methods to achieve immediate and accessible forecasting. Specifically, it aims to verify the possibility of immediate demand forecasting based on an alternative approach using Pbands technical indicator for poetry books in the European Quartet countries.
 Methods: The study performs the demand forecasting based on the technical analysis of the Google Trends data search in case of the keyword poetry in the European Quartet countries by several statistical methods, including the commonly used ETS statistical methods, ARIMA method, ARFIMA method, BATS method based on the combination of the Cox-Box transformation model and ARMA, artificial neural networks, the Theta model, a hybrid model, and an alternative approach of forecasting using Pbands indicator. The study uses MAPE and RMSE approaches to measure the accuracy.
 Findings & value added: Although most currently available demand prediction models are either slow or complex, the entrepreneurial practice requires fast, simple, and accurate ones. The study results show that the alternative Pbands approach is easily applicable and can predict short-term demand changes. Due to its simplicity, the Pbands method is suitable and convenient to monitor short-term data describing the demand. Demand prediction methods based on technical indicators represent a new approach for demand forecasting. The application of these technical indicators could be a further forecasting models research direction. The future of theoretical research in forecasting should be devoted mainly to simplifying and speeding up. Creating an automated model based on primary data parameters and easily interpretable results is a challenge for further research.

Hybrid posttensioned rocking (HPR) frame buildings: Low-damage vs low-loss paradox

The 2010-11 Canterbury Earthquake Sequence inflicted seismic losses worth more than $40B, which is about 25% of the GDP of New Zealand (as per 2011 data). More than 80% of these losses were insured, which comprised of more than $10B covered by the Earthquake Commission (a New Zealand crown entity providing insurance to residential property owners) and more than $22B (comprising of roughly equal split between domestic and commercial claims) by private insurers [1]. The scale of financial impact has been perceived to be disproportionately large given the building regulatory regime in New Zealand is relatively stringent and the earthquakes and aftershocks were of moderate magnitude. As it is well known that some of the major faults spread in the Wellington region and the subduction boundary passing through the centre of New Zealand can generate much bigger earthquakes (upwards of magnitude 8), people are left pondering whether New Zealand is able to cope with the financial impact of larger earthquakes. This fearful realisation gradually led to people being dissatisfied with merely life-safe buildings and demanding more resilient buildings that meet the objectives of performance based design; i.e. suffer less damage, incur less loss, and can remain functional after earthquakes.
 In light of the extensive building damage resulting in high financial loss in recent earthquakes, practicing engineers and researchers in New Zealand have been advocating for revising the current design approach to improve performance of new structures and infrastructure in future earthquakes [2-5]. As a result, large proportion of buildings constructed in the last decade (including those built to replace earthquake-damaged buildings) have shied away from the traditional damage-friendly ductile structural systems and instead adopted one of the new and emerging structural systems claimed to be “low-damage”. In many cases, the adopted structural systems are not covered by existing design standards and are approved as alternate solutions through expert peer review. The “low-damage” attribute of most structural systems has been validated by component (or sub-assembly) level experimental tests, but their interactions with other building components and implications of their use in buildings have not been rigorously scrutinised. Hence, the rushed adoption of some of these systems in buildings can surprise the engineering community in future earthquakes with mismatch between the expected and real performances of the buildings; akin to what New Zealand engineering fraternity is currently going through due to realisation of poor seismic performance of precast hollow-core flooring system that has been widely used in New Zealand buildings without rigorous scrutiny.
 One such “low-damage” structural system is precast post-tensioned rocking frames with supplemental energy dissipaters. This paper summarises the development of this structural system, critically reviews the literature reporting the seismic performance of this system, and qualitatively evaluates system-level implications of its use in buildings. This paper is intended to better inform engineers of the likely seismic performance of buildings with this structural system so that they can optimise its benefits by giving due consideration to its effect on other building components.

Simplified approach for ground reinforcement design to enhance critical speed

In recent years, there have been significant advances in the railway sector, with a substantial increase in train speed, resulting in new challenges for the technical community in terms of infrastructure performance. When the supporting soil of the railway track is soft, the train speed can approach the speed of wave propagation in the track-ground system, giving rise to the so-called critical speed effect. This effect is characterized by the great amplification of the track response with dramatic consequences in terms of safety, ground-borne vibrations and maintenance costs. This well-known issue can be mitigated in several ways, one of them based on the reinforcement of the soil with columns. Bearing that in mind, the present paper aims to study the enhancement in the critical speed of the railway system achieved by a soil reinforcement with jet grouting columns, for a homogeneous and layered ground. Despite the inefficiency verified for the homogeneous scenario, the reinforcement of layered grounds produces a considerable improvement in the critical speed of the system. It has been proved that deepening the reinforced columns in the stiffer layer does not lead to a continuous improvement in the critical speed of the system. Furthermore, a simplified methodology capable of accurately predicting the critical speed for reinforced grounds is proposed. A validation study showed the high accuracy of the simplified methodology in predicting critical speed, proving to be an interesting tool for engineering purposes.