Development of a Wireless MEMS Multifunction Sensor System and Field Demonstration of Embedded Sensors for Monitoring Concrete Pavements, TR-637, 2016

Pavements tend to deteriorate with time under repeated traffic and/or environmental loading. By detecting pavement distresses and damage early enough, it is possible for transportation agencies to develop more effective pavement maintenance and rehabilitation programs and thereby achieve significant cost and time savings. The structural health monitoring (SHM) concept can be considered as a systematic method for assessing the structural state of pavement infrastructure systems and documenting their condition. Over the past several years, this process has traditionally been accomplished through the use of wired sensors embedded in bridge and highway pavement. However, the use of wired sensors has limitations for long-term SHM and presents other associated cost and safety concerns. Recently, micro-electromechanical sensors and systems (MEMS) and nano-electromechanical systems (NEMS) have emerged as advanced/smart-sensing technologies with potential for cost-effective and long-term SHM. This two-pronged study evaluated the performance of commercial off-the-shelf (COTS) MEMS sensors embedded in concrete pavement (Final Report Volume I) and developed a wireless MEMS multifunctional sensor system for health monitoring of concrete pavement (Final Report Volume II).

Soft computing based parameter identification in pavements and geomechanical systems

Accurate estimation of road pavement geometry and layer material properties through the use of proper nondestructive testing and sensor technologies is essential for evaluating pavement’s structural condition and determining options for maintenance and rehabilitation. For these purposes, pavement deflection basins produced by the nondestructive Falling Weight Deflectometer (FWD) test data are commonly used. The nondestructive FWD test drops weights on the pavement to simulate traffic loads and measures the created pavement deflection basins. Backcalculation of pavement geometry and layer properties using FWD deflections is a difficult inverse problem, and the solution with conventional mathematical methods is often challenging due to the ill-posed nature of the problem. In this dissertation, a hybrid algorithm was developed to seek robust and fast solutions to this inverse problem. The algorithm is based on soft computing techniques, mainly Artificial Neural Networks (ANNs) and Genetic Algorithms (GAs) as well as the use of numerical analysis techniques to properly simulate the geomechanical system. A widely used pavement layered analysis program ILLI-PAVE was employed in the analyses of flexible pavements of various pavement types; including full-depth asphalt and conventional flexible pavements, were built on either lime stabilized soils or untreated subgrade. Nonlinear properties of the subgrade soil and the base course aggregate as transportation geomaterials were also considered. A computer program, Soft Computing Based System Identifier or SOFTSYS, was developed. In SOFTSYS, ANNs were used as surrogate models to provide faster solutions of the nonlinear finite element program ILLI-PAVE. The deflections obtained from FWD tests in the field were matched with the predictions obtained from the numerical simulations to develop SOFTSYS models. The solution to the inverse problem for multi-layered pavements is computationally hard to achieve and is often not feasible due to field variability and quality of the collected data. The primary difficulty in the analysis arises from the substantial increase in the degree of non-uniqueness of the mapping from the pavement layer parameters to the FWD deflections. The insensitivity of some layer properties lowered SOFTSYS model performances. Still, SOFTSYS models were shown to work effectively with the synthetic data obtained from ILLI-PAVE finite element solutions. In general, SOFTSYS solutions very closely matched the ILLI-PAVE mechanistic pavement analysis results. For SOFTSYS validation, field collected FWD data were successfully used to predict pavement layer thicknesses and layer moduli of in-service flexible pavements. Some of the very promising SOFTSYS results indicated average absolute errors on the order of 2%, 7%, and 4% for the Hot Mix Asphalt (HMA) thickness estimation of full-depth asphalt pavements, full-depth pavements on lime stabilized soils and conventional flexible pavements, respectively. The field validations of SOFTSYS data also produced meaningful results. The thickness data obtained from Ground Penetrating Radar testing matched reasonably well with predictions from SOFTSYS models. The differences observed in the HMA and lime stabilized soil layer thicknesses observed were attributed to deflection data variability from FWD tests. The backcalculated asphalt concrete layer thickness results matched better in the case of full-depth asphalt flexible pavements built on lime stabilized soils compared to conventional flexible pavements. Overall, SOFTSYS was capable of producing reliable thickness estimates despite the variability of field constructed asphalt layer thicknesses.

Numerical analysis of wooden slabs with perforations under fire conditions

Wood is considered an ideal solution for floors and roofs building construction, due the mechanical and thermal properties, associated with acoustic conditions. These constructions have good sound absorption, heat insulation and relevant architectonic characteristics. They are used in many civil applications: concert and conference halls, auditoriums, ceilings, walls… However, the high vulnerability of wooden elements submitted to fire conditions requires the evaluation of its structural behaviour with accuracy. The main objective of this work is to present a numerical model to assess the fire resistance of wooden cellular slabs with different perforations. Also the thermal behaviour of the wooden slabs will be compared considering different material insulation, with different sizes, inside the cavities. A transient thermal analysis with nonlinear material behaviour will be solved using ANSYS© program. This study allows to verify the fire resistance, the temperature evolution and the char-layer, throughout a wooden cellular slab with perforations and considering the insulation effect inside the cavities.

Rutting performance of asphalt pavements

Cold in-place recycling (CIR) and cold central plant recycling (CCPR) of asphalt concrete (AC) and/or full-depth reclamation (FDR) of AC and aggregate base are faster and less costly rehabilitation alternatives to conventional reconstruction for structurally distressed pavements. This study examines 26 different rehabilitation projects across the USA and Canada. Field cores from these projects were tested for dynamic modulus and repeated load permanent deformation. These structural characteristics are compared to reference values for hot mix asphalt (HMA). A rutting sensitivity analysis was performed on two rehabilitation scenarios with recycled and conventional HMA structural overlays in different climatic conditions using the Mechanistic Empirical Pavement Design (MEPDG). The cold-recycled scenarios exhibited performance similar to that of HMA overlays for most cases. The exceptions were the cases with thin HMA wearing courses and/or very poor cold-recycled material quality. The overall conclusion is that properly designed CIR/FDR/CCPR cold-recycled materials are a viable alternative to virgin HMA materials.

Effects of truck traffic on top-down fatigue cracking performance of flexible pavements using a new mechanics-based analysis framework

The mechanics-based analysis framework predicts top-down fatigue cracking initiation time in asphalt concrete pavements by utilising fracture mechanics and mixture morphology-based property. To reduce the level of complexity involved, traffic data were characterised and incorporated into the framework using the equivalent single axle load (ESAL) approach. There is a concern that this kind of simplistic traffic characterisation might result in erroneous performance predictions and pavement structural designs. This paper integrates axle load spectra and other traffic characterisation parameters into the mechanics-based analysis framework and studies the impact these traffic characterisation parameters have on predicted fatigue cracking performance. The traffic characterisation inputs studied are traffic growth rate, axle load spectra, lateral wheel wander and volume adjustment factors. For this purpose, a traffic integration approach which incorporates Monte Carlo simulation and representative traffic characterisation inputs was developed. The significance of these traffic characterisation parameters was established by evaluating a number of field pavement sections. It is evident from the results that all the traffic characterisation parameters except truck wheel wander have been observed to have significant influence on predicted top-down fatigue cracking performance.

Identification of critical input variables for risk-based cost estimates for road maintenance and rehabilitation

An estimation of costs for maintenance and rehabilitation is subject to variation due to the uncertainties of input parameters. This paper presents the results of an analysis to identify input parameters that affect the prediction of variation in road deterioration. Road data obtained from 1688 km of a national highway located in the tropical northeast of Queensland in Australia were used in the analysis. Data were analysed using a probability-based method, the Monte Carlo simulation technique and HDM-4’s roughness prediction model. The results of the analysis indicated that among the input parameters the variability of pavement strength, rut depth, annual equivalent axle load and initial roughness affected the variability of the predicted roughness. The second part of the paper presents an analysis to assess the variation in cost estimates due to the variability of the overall identified critical input parameters.

Interoperable Standards Development : Final Report

Since 1995 the buildingSMART International Alliance for Interoperability (buildingSMART)has developed a robust standard called the Industry Foundation Classes (IFC). IFC is an object oriented data model with related file format that has facilitated the efficient exchange of data in the development of building information models (BIM). The Cooperative Research Centre for Construction Innovation has contributed to the international effort in the development of the IFC standard and specifically the reinforced concrete part of the latest IFC 2x3 release. Industry Foundation Classes have been endorsed by the International Standards Organisation as a Publicly Available Specification (PAS) under the ISO label ISO/PAS 16739. For more details, go to http://www.tc184- sc4.org/About_TC184-SC4/About_SC4_Standards/ The current IFC model covers the building itself to a useful level of detail. The next stage of development for the IFC standard is where the building meets the ground (terrain) and with civil and external works like pavements, retaining walls, bridges, tunnels etc. With the current focus in Australia on infrastructure projects over the next 20 years a logical extension to this standard was in the area of site and civil works. This proposal recognises that there is an existing body of work on the specification of road representation data. In particular, LandXML is recognised as also is TransXML in the broader context of transportation and CityGML in the common interfacing of city maps, buildings and roads. Examination of interfaces between IFC and these specifications is therefore within the scope of this project. That such interfaces can be developed has already been demonstrated in principle within the IFC for Geographic Information Systems (GIS) project. National road standards that are already in use should be carefully analysed and contacts established in order to gain from this knowledge. The Object Catalogue for the Road Transport Sector (OKSTRA) should be noted as an example. It is also noted that buildingSMART Norway has submitted a proposal

Numerical analyses of crack spacing due to shrinkage in reinforced concrete slabs

Shrinkage cracking is commonly observed in concrete flat structures such as highway pavements, slabs, and bridge decks. Crack spacing due to shrinkage has received considerable attention for many years [1-3]. However, some aspects concerning the mechanism of crack spacing still remain un-clear. Though it is well known that the interval of the cracks generally falls with a range, no satisfactory explanation has been put forward as to why the minimum spacing exists.

Justifications in young children’s language in an early childhood classroom

This paper examines the interactional phenomenon of justification as it is produced in young children’s language. A justification provides a reason for one’s position and can be produced in children’s language at an early age. There are various pragmatic reasons for justifications. For example, justifications may be drawn upon by members to compensate for the disruption of the existing social order or to explain something that is possibly questionable. Justifications are also drawn upon to extend or close disputes. This study uses the analytical techniques of conversation analysis and membership categorisation to analyse video-recorded and transcribed interactions of young children (aged 4-6 years) in a preparatory classroom in a primary school in Australia. The focus is an episode that occurred within the block play area of the classroom that involved a dispute of ownership relating to a small, wooden plank. In analysing this dispute, justifications were frequent occurrences and the young participants drew upon justificatory devices in their everyday arguments. As the turns surrounding the justificatory language were examined, a pattern emerged: in each excerpt observed, a justification arose in response to a challenge. This pattern provided the basis for developing a model that helped to discern where, why and what type of justifications occurred in the interaction. To depict this interactional phenomenon, the model of ‘if x, then y’ was used, ‘x’ referring to the challenge or prompt, and ‘y’ referring to the justificatory response. Justifications related to the concepts of ownership and were used as devices by those engaged in disputes to support their positions and provide reasons for their actions. The children drew upon these child-constructed rules as resources to use in disputes with their peers, in order to construct and maintain the social order of the block area in the classroom.

Lighter than Tai

YEAR: 2008 ROLE: Performer FORMAT: Live Art Event at Tiananmen Square Beijing, China (3 hours) and Later on Summit of Mt. Tai Shan, Shandong Province, China (6 hrs + 3 hrs). WITH: Solo WHAT: In the Hall of Reverence on Tiananmen Square, Beijing Mao Zedong's body lies in state surrounded by flowers and draped with a Red Flag of Communist China. His casket with a glass top lies on a black stone from Mt. Tai, reflecting the quotation from Sima Qian (China's Han Dynasty historian) that "One's life can be weightier than Mt. Tai or lighter than a goose feather". This pair of performances were a quiet, personal reflection upon what such a once revolutionary expression might mean in today's very different time and place. The work was conceived during the Olympic Cultural Festival showing of Intimate Transactions (www.intimatetransactions.com) - during the tumultuous times leading up to China's proudly staged August 2008 Olympics. The rise and rise of China had long been generating major geopolitical, ecological and cross-cultural shifts throughout the region and beyond. In this dramatic epicentre of change and at a time of such great national pride, how might we each act in ways that are ecologically 'mighty' and yet simultaneously have an impact lighter than a goosefeather? This is both a question for China in its relations with the autonomous provinces and the environment as it is for all of us in our own 'local' affairs. However ecologically speaking all that is of local concern is of global concern and noone can therefore be exempt from the need to sustain that which we share in common and must all protect for the future. Performance 1: Tiananmen Square, Beijing: Dropping 100 goose feathers. Performance 2: The summit of Mt Tai, Shandong Province. Building a mountain from Goose Feathers. SHOWING HISTORY: 1: Anniversary of Protest Crackdown, Jun 8th 2008. 2: Dawn on Tai Shan's summit, 15th June, 2008 DETAILS: Performance 1: Begin an hour after dawn (5.45am) in Tiananmen Square Bring pre-prepared performance shirt, a bag of goose feathers tipped with red. Begin at the "Gate of Heavenly Peace" under the image of Chairman Mao. Circumnavigate the world's largest open and the most surveilled public space 5 times dropping feathers periodically. Meditate on Forces of Change. Finally enter Chairman Mao's mausoleum with the masses and move quietly past his preserved body. End the performance at the Gate of Heavenly Peace 3 hours later. Performance 2: Walk up Mt. Tai Shan in silence meditating on Forces of Change (6 hours). Stay overnight on the summit. Begin an hour before dawn (3.45am) in silence. Bring performance shirt, a sack of goose feathers and a simple wooden structure. On the sunrise viewing side of the mountain build a miniature, fragile 'mountain' in goose feathers and sticks on the edge of a sheer precipice. Watch the sun rise as the feathers blow away into the valley deep below (3 hours).

An investigation of the effects of lateral wind loading on pole frame housing

This project set out to investigate the behaviour of a pole frame house subjected to a lateral wind load. The behaviour of poles embedded in the ground was examined. The existing theoretical methods for determining lateral load capacity of an embedded pole were reviewed, and three common methods of pole embedment were tested at different depths to gauge the response of poles and types of pole embedment to a lateral load. The most suitable embedment method was used in the foundation for a full-scale model pole house, which was constructed and tested at various stages during the construction to examine the response of a pole house to lateral wind load. The full scale testing was also used to monitor the effect of the various structural components on the overall stiffuess of the house. The results from the full scale tests were used to calibrate a computer model of a pole house which could then be used to predict the behaviour of different configurations of pole house construction without the need for further expensive full scale tests.