1. Faculty of Civil Engineering , Wroclaw University of Science and Technology , Wybrzeże Wyspiańskiego 27 , Wroclaw , Poland ; Faculty of Civil and Environmental Engineering, Jimma Institute of Technology , Jimma University , Oromia , Ethiopia
2. College of Engineering and Technology , Asosa University , Asosa , Ethiopia
3. Faculty of Civil and Environmental Engineering, Jimma Institute of Technology , Jimma University , Oromia , Ethiopia