1. Department of Civil Engineering, Engineering Built Environment and IT (EBIT), University of Pretoria, Private Bag X20, Lynnwood Rd., Hatfield 0083, South Africa (Corresponding author), e-mail: wynand.steyn@up.ac.za, https://orcid.org/0000-0001-5893-3733
2. Department of Civil Engineering, Engineering Built Environment and IT (EBIT), University of Pretoria, Private Bag X20, Lynnwood Rd., Hatfield 0083, South Africa, https://orcid.org/0000-0002-3368-2947