ICAHETS - 2011

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Browsing ICAHETS - 2011 by Author "Mampearachchi, WK"

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    item: Conference-Abstract
    Design of rigid pavement joint spacing for rural roads.
    (Department of Civil Engineering, 2011-07) Karunarathne, AMAN; Mampearachchi, WK; Nanayakkara, SMA; Pasindu, HR
    When it is compared with the flexible pavements, tensile stresses along the pavement layers are more significant in rigid pavements. Shrinkage stresses and thermal stresses are the dominant contributors to develop the tensile stresses in rigid pavements. Providing lateral joints in appropriate spacing is one of the better solutions to overcome the said stresses. Rigid pavements are usually exposed to solar radiation severely and this incorporates with the development of varying thermal stresses as well. Rate of receiving heat flux from solar radiation, thermal properties of concrete and heat loss from concrete due to convection parameters of surrounding are the main influences of the temperature variation of an exposed concrete slab. This research produces a methodology to incorporate the temperature variation of concrete slab by the use of a 3D finite element model (FEM) approach, to estimate the relevant deformation of concrete due to its exposure to the solar radiation. ANSYS (Version 12.0.1) was used for this FEM analysis, to obtain thermal variations of an exposed pavement slab. Laboratory scale slab was used to verify the results obtained from the FEM. Verified FEM is capable of producing the lateral stresses and its corresponding deformations of concrete pavement for daily thermal variation. Lateral deformations due to shrinkage effect were calculated according to the BS 8110 part 2:1985 shrinkage model. Opening of the joint crack is restricted by the load transfer requirement in consecutive pavement slabs. Aggregate interlocking is an efficient load transfer mechanism for the thin concrete pavements which are commonly used in rural roads. Effectiveness of aggregate interlocking mechanism depends on strength of the concrete, strength of aggregate, maximum aggregate size, friction of cracked surfaces, slab thickness and joint opening. Lateral joint opening vary with the pavement life and it is directly affected to the Load Transfer Efficiency (LTE). Another key aspect of this study is to carry out an experimental investigation to obtain a relationship between crack width and LTE in a rigid pavement joints. 150 mm thick test concrete pavement slab was cast with grade 25 concrete, 20 mm coarse aggregate was used to obtain the LTE at cracked joint. Standard single axel, single wheel load of 40 kN was used to simulate the tire load. From the obtained results, it was observed that LTE decreases nonlinearly with the increase of crack width. This paper describes a procedure to obtain the joint spacing for thin rigid pavements by the use of the FEM results and LTE experiment outcome. According to the study, joint spacing for rigid pavements in rural areas can be provided even beyond the specified values of ACPA.
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    item: Conference-Abstract
    Development of road accident reporting mechanism for Sri Lanka
    (Department of Civil Engineering, 2011-07) Mampearachchi, WK; Pasindu, HR
    The total population had risen from 14.8 million tol8.7 million between 1981 and 2001 (last census data), and the population growth is reducing and comparatively small about 1.2% per year. More than population increases; the increasing fleets have had a damaging effect on the number of road accident in Sri Lanka. The vehicle population has risen from 0.213 million in 1977 to 3.34 million in 2008. Over 1.06 million motor vehicles of all varieties were registered during the period between 1990 and 2001. Road accident has become one of the leading factors which have contributed for increasing the accident death rate in Sri Lanka. It seems that current safety policies are not sufficient to decrease the accidents in Sri Lanka. To develop better road safety policies, it is needed to identify the safety issues of the country.. A vision, a target plan, a programme of work and short term, medium and long term strategies should be set out in this policy. However, current accident reporting and analysis has not helped to identify the road safety issues of the country. This study was conducted to identify the deficiencies in the accident reporting and analysis and propose a suitable accident reporting and analyzing mechanism forSri Lanka. The study team reviewed the current accident reporting and analysis procedure and identified the useful data needed for reporting and analysis. Data will be collected under following categories in the revised accident data reporting form: (1) Accident Tracking Data, (2) Road Environment Data, (3) Driver/ Pedestrian involved Data, (4) Non- Motorized data, (5) Causalities and (6) Accident diagram. A Methodology has been proposed to obtain accident location. Road geometric and land use data has been included for road environment data. Vehicle involvement and Non- motorized involvement data has been included in the accident reporting form as sequential of events to better analysis the accident involvement. A new form has been Improved to include seating position, safety devised used and mode of transport of casualties. Developed accident reporting form can be used for recording and analyzing the accident data more efficiently.