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Pretoria, South Africa

A statistical property of non-stationary time series is applied to quantify the long-run equilibrium relationship between mechanisms of pavement failure and deterioration. The concept is applied to measured pavement responses from an Accelerated Pavement Test (APT) conducted on the thin (185 mm) Continuously Reinforced Concrete Pavement (CRCP) of the Ben Schoeman freeway in South Africa. The statistical property is that of cointegration, which allows testing for the existence of equilibrium relationships among trending variables within fullydynamic specification frameworks. The predominant failure mechanisms leading to punchout are known to be loss of load transfer capability at transverse cracks and the deterioration of substructure support. The long-term relationship between proxy variables for the mechanisms leading to punchout and pavement deterioration is determined. The average long-term relationship between a change in relative movement and a change in surface deflection at transverse cracks is found to be 17.5. This means that on average a 1.0% increase in relative movement will translate into a 17.5% increase in surface deflection and vice versa. The empirical quantification of the long-term equilibrium relationships between pavement mechanisms of failure and deterioration offers the potential to improve the reliability of design systems and may also be used in pavement management. © RILEM 2012. Source


ter Haar T.,BKS Pty Ltd
Proceedings of Institution of Civil Engineers: Management, Procurement and Law | Year: 2012

The award-winning Moses Mabhida Stadium, completed in October 2009, is a world-class multi-purpose sporting facility and an iconic, innovative and sustainable landmark in Durban which played host to seven spectacular Fifa World Cup 2010 matches, including a semi-final. The 106m arch, inspired by the Y-shape of the South African flag, was a world first in terms of the design of the arch foundations, involving diaphragm walling to bedrock, massive cappings and springer plinths. Another South African first was achieved for precast design and installation in stadiums. Source


De Wet D.P.G.,BKS Pty Ltd
Journal of the South African Institution of Civil Engineering | Year: 2010

Weigh-in-motion (WIM) scales are installed on various higher order roads in South Africa to provide traffic loading information for pavement design, strategic planning and law enforcement. Some WIM systems produce anomalies that cannot be satisfactorily explained even by highly experienced professionals. Much of the problem relates to the difficulty in determining the appropriate calibration factors to correct systematic measurement error for WIM systems and the inadequacy of data quality management methods. The author has developed a post-calibration method for WIM data, called the Truck Tractor (TT) method, to correct the magnitude of recorded axle loads in retrospect. In addition, it incorporates a series of data quality checks. The TT method is robust, accurate and adequately simple for use on a routine basis for a wide variety of South African WIM systems. The calibration module of the TT method (i.e. the procedure to determine the calibration factor kTT) has been accepted by SANRAL and incorporated into the model it uses to quantify the cost of overloading on toll concessions. Some of the data quality checking concepts are also being considered for further use and threshold values for tests are being refined by SANRAL for this purpose. Source


Bokelman K.,Aurecon SA Pty Ltd | Bastiaanse G.,BKS Pty Ltd | Du Plessis G.,Goba Pty Ltd. | Heymann F.,Bigen Africa Services Pty Ltd | And 3 more authors.
Structural Engineering International: Journal of the International Association for Bridge and Structural Engineering (IABSE) | Year: 2011

South Africa embarked on an accelerated infrastructure development program in preparation of the 2010 FIFA World Cup. This paper describes the structural aspects and the construction of five of ten stadiums which were prepared for this event. The stadiums represent an interesting variety of design concepts. The Soweto Stadium is the biggest with a capacity of 89 000. The stadiums in Cape Town and Durban are located in major economic and tourist areas, and significant investment was made to develop signature structures. For the more rural stadiums in Nelspruit and Polokwane, the challenge was to develop the facilities within strict time and budget constraints. Source


Findlay W.,BKS Pty Ltd | Kromhout F.,BKS Pty Ltd
Concrete Repair, Rehabilitation and Retrofitting III - Proceedings of the 3rd International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR 2012 | Year: 2012

Bridge B421 is located on Route R555 between eMalahleni (Witbank) and Middelburg in Mpumalanga, South Africa. On 6 January 2011, after heavy rains, road users reported that a large sinkhole has formed in the road behind the eMalahleni Abutment. The routine road maintenance contractor investigated the cause of the sink hole and found that the abutment and wing wall on the downstream side of the bridge has failed. The South African National Roads Agency SOC Limited (SANRAL) contacted an experienced consulting bridge engineer to investigate the reason for the failure. Bridge B421 is a simply supported 4-span bridge with span lengths of 16 m each. The deck consists of simply supported reinforced concrete voided slabs. The piers are wall-type on spread footings and the abutments are wall-type closed abutments with splayed wing walls. The three piers and the Middelburg Abutment were founded on weathered mudstone, but contrary to good practice, the eMalahleni Abutment was founded on clayey sand. The shift in the river channel due to scour during 32 years had shifted the position of river scour to the one abutment. When the Witbank Dam sluice gates were opened on 6 and 7 January 2011, the lack of foundation support due to undermining scour and rapid drawdown water pressure behind the abutment wall combined to cause half of the abutment to fail completely. Route R555, which carries more than 14 000 vehicles a day was closed for traffic. This paper describes the investigations done and the actions taken to support the deck temporarily while constructing a new abutment, supported on piles, underneath the overhanging deck structure, as well as additional works to upgrade the bridge. © 2012 Taylor & Francis Group. Source

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