Civil Engineering March 2022 | Vol 30 No 2

Civil Engineering March 2022 35 RECOMMENDED DAF FOR SOUTH AFRICA Based on the following it is reasonable to assume that the ARCHES recommenda- tion for a class B road can be adopted for South Africa: Q Q The studies were performed based on European traffic where five axle vehicles dominate the GVW tail and where the GVW limit is 40 tonnes. Studies have shown that South African heavy vehicles have more axles and are heavier than European vehicles. Q Q It has been shown that heavier vehicles cause lower dynamic amplification than lighter vehicles. In South Africa it was shown that the vehicles that cause the largest load effects are seven axle vehicles with a mean weight of 530 kN. In Europe the largest load effects are caused by five axle vehicles with a mean weight of 410 kN. It is thus reasonable to believe that, based on vehicle weight, the dynamic amplifica- tion at characteristic levels in South Africa will be lower than in Europe. Q Q Bridge construction materials and bridge types in South Africa are similar to those in Europe. Q Q Pavements on South African highways, where the heaviest vehicles are meas- ured, are generally well maintained and should at least conform to ISO road class B. CONCLUSIONS This article shows that great variation exists in how dynamic amplification is treated in codes worldwide. Codes mostly take a worst-case DAF from all vehicles and apply it to the heaviest vehicles that cause the largest load effects. Research performed subsequently has shown that dynamic amplification may not be as high as initially thought. A significant advance- ment was the introduction of the ADR and the notion that dynamic amplification should be assessed at characteristic level. This was employed in the ARCHES study and resulted in significantly lower DAFs compared to current code values. By comparing South African vehicle characteristics and pavement conditions it was argued that the values presented in the ARCHES report can be applied in South Africa in the absence of a more detailed local study.  A complete list of references can be ob- tained from the author. This article was originally published in the Proceedings of the Seventh Inter­ national Conference on Structural Engineering, Mechanics and Computation (2 to 4 September 2019, Cape Town), and is reproduced here with the permission of the publisher: Van der Spuy, PF & Lenner, R. 2019. Dynamic amplification factor for South African Bridges. Structural Engineering, Mechanics and Computation. Cape Town: Taylor & Francis. Pile Driving Analyzer ® (PDA) • Calculate bearing capacity and assess structural integrity • Assess dynamic driving stresses and hammer performance • Complete with CAPWAP ® , GRLWEAP14, and iCAP ® software, as well as PDIPLOT to summarize results To learn more about the PDA, visit www.pile.com.