Ephrem Taddesse

• Alamnie, Mequanent Mulugeta; Taddesse, Ephrem & Hoff, Inge (2023). A study on permanent deformation and fatigue damage interaction in asphalt concrete . Construction and Building Materials. ISSN 0950-0618. 407, s. 1–15. doi: 10.1016/j.conbuildmat.2023.133473. Fulltekst i vitenarkiv
• Alamnie, Mequanent Mulugeta; Taddesse, Ephrem & Hoff, Inge (2022). Permanent deformation and fatigue damage interaction in asphalt concrete using energy approach. I Hoff, Inge; Mork, Helge & Saba, Rabbira G. (Red.), Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields, Volume 3. CRC Press. ISSN 978-1-003-22291-0. s. 118–127. doi: 10.1201/9781003222910-12. Fulltekst i vitenarkiv
• Alamnie, Mequanent Mulugeta; Taddesse, Ephrem & Hoff, Inge (2022). Advances in Permanent Deformation Modeling of Asphalt Concrete—A Review. Materials. ISSN 1996-1944. 15(10). doi: 10.3390/ma15103480. Fulltekst i vitenarkiv
• Alamnie, Mequanent Mulugeta; Taddesse, Ephrem & Hoff, Inge (2022). Thermo-piezo-rheological characterization of asphalt concrete. Construction and Building Materials. ISSN 0950-0618. 329. doi: 10.1016/j.conbuildmat.2022.127106. Fulltekst i vitenarkiv Vis sammendrag

  The linear viscoelastic (LVE) properties of asphalt concrete is investigated in this paper using a controlled-strain triaxial dynamic modulus test over wide frequency, temperature, and confining pressure ranges. The time–temperature-pressure superposition principle (TTPSP) is applied to validate the thermo-piezo-rheological simplicity of the tested materials using triaxial master curves. The LVE response is found highly stressdependent at intermediate and high temperatures. The Prony series modeling of time-domain properties ascertains that confining pressure strongly correlates with long-term relaxation modulus, the absolute maximum slope of the relaxation modulus, and viscoelastic damage parameter. The stress triaxiality ratio concept is applied, and a new shift model is proposed that takes the triaxiality ratio as an internal state variable in the TTPSP. The model prediction agrees well with the experimental data. Moreover, a relationship between the longterm relaxation modulus and the triaxiality ratio is established. The triaxiality ratio coupled with TTPSP can accurately describe the stress-dependent response of asphalt concrete in the LVE domain.

• Alamnie, Mequanent; Taddesse, Ephrem & Hoff, Inge (2021). Viscoelastic characterization and comparison of Norwegian asphalt mixtures using dynamic modulus and IDT tests. I Hoff, Inge; Mork, Helge & Saba, Rabbira G. (Red.), Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields, Volume 1. Proceedings of the eleventh international conference 8-10 June, Trondheim, Norway. CRC Press. ISSN 978-1-003-22288-0. s. 118–128. doi: 10.1201/9781003222880-12. Fulltekst i vitenarkiv
• Andreu Regué, Barrufet & Taddesse, Ephrem (2020). Condition Assessment of Norwegian Bridge Elements Using Existing Damage Records. Lecture Notes in Mechanical Engineering. ISSN 2195-4356. s. 716–722. doi: 10.1007/978-3-030-48021-9_79. Vis sammendrag

  Abstract. The Norwegian Public Roads Administration (NPRA) has recorded bridge element damages in a database for all the bridges it manages since the 1990s. This paper presents a comparison of three methods to establish element condition based on damage records. The methods consist in a non-parametric procedure based on the worst damage registered in the element, linear regression considering also bridge and road characteristics data and classification through an artificial neural network. The methods are assessed using a set of 159 bridges inspected in 2016. The results show that diagnostics of bridge element condition can reach high accuracy by using an artificial neural network classifier and taking into account existing damage records and bridge data.

• Taddesse, Ephrem (2017). Pavement Rutting Prediction Models for the coastal roads of southern Norway. I Loizos, Andreas; Al-Quadi, Imad & Scarpas, Tom (Red.), Bearing Capacity of Roads, Railways and Airfield. CRC Press. ISSN 9781138295957. s. 1375–1382. doi: 10.1201/9781315100333-197.
• Taddesse, Ephrem & Mork, Helge (2009). Roughness Progression Models by Regression and Artificial Neural Network Techniques. I Tutumluer, Erol & Al-Qadi, Imad L. (Red.), Bearing Capacity of Roads, Railways and Airfields. CRC Press. ISSN 978-0-415-87199-0. s. 521–530.
• Taddesse, Ephrem & Mork, Helge (2009). Pavement Performance Models For the Ethiopian Pavement Management System. I Birgonul, Talat & Azhar, Salman (Red.), Proceedings of the Fifth International Conference on Construction in the 21st Century Collaboration and Integration in Engineering, Management and Technology. CITC-V. s. 1266–1274.

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• Taddesse, Ephrem & Andreu Regué, Barrufet (2018). Condition Assessment of Norwegian Bridge Elements Using Existing Damage Records.
• Taddesse, Ephrem (2017). skademekanismer og Tilstandsregistrering – Pavement Performance Criteria .
• Taddesse, Ephrem (2017). Dimensjonering av veger i Norge 2017.
• Taddesse, Ephrem (2016). Pavement Performance Criteria.
• Taddesse, Ephrem (2016). Dimensjonering av veger i Norge.
• Taddesse, Ephrem (2014). CENG 6307- Advanced Geometric Design of Highways and Airfields.
• Taddesse, Ephrem (2013). Intelligent flexible pavement rutting prediction models: the case of Norwegian main road network.
• Taddesse, Ephrem (2013). Pavement rutting prediction models using artificial neural network technique.
• Taddesse, Ephrem (2011). Tilstandsutviklingmodeller for det norske vegnettet.
• Taddesse, Ephrem (2009). Pavement performance modles for the Ethiopian pavement management system.
• Alamnie, Mequanent Mulugeta; Taddesse, Ephrem & Hoff, Inge (2024). Laboratory-based study of viscoelastic, viscoplastic and fatigue damage of asphalt concrete. University of Agder. ISSN 978-82-8427-183-5. Fulltekst i vitenarkiv Vis sammendrag

  Asphalt concrete is one of the most important road building materials worldwide. This material exhibits unique chemical, physical and mechanical properties. The most well-known mechanical properties are the viscoelastic, viscoplastic-viscodamage (deformability), fatigue cracking, and fracture under different environmental and loading scenarios. The investigation of bituminous mixtures focuses on four main properties; stiffness and stiffness change, fatigue and damage law evolution, permanent deformation and accumulation at high temperatures, and cracks and crack propagation at low temperatures. Every mechanistic-empirical (ME) and mechanistic pavement design method attempts to model and simulate these four properties for an accurate performance prediction. The main contributions of this research project are focused on the linear viscoelastic and damage responses of asphalt concrete mixtures. This thesis presents the uniaxial and triaxial viscoelastic responses and the interaction between the permanent deformation and uniaxial cyclic fatigue responses of asphalt concrete mixtures. To achieve these objectives, extensive laboratory investigations were performed using the latest mechanistic asphalt testing equipment. The linear viscoelastic (LVE) properties of asphalt concrete are crucial for mechanistic pavement design. The rutting and fatigue cracking properties of asphalt concrete are directly correlated with the LVE stiffness. In the first phase, the research emphasized the LVE response in both uniaxial and triaxial states, as well as the axial and indirect tensile (IDT) testing modes. Three of the appended papers extensively addressed these properties. The important conclusions from this phase were the triaxiality of the LVE properties at intermediate and high temperatures, and the good correlation of the IDT and axial mode of the stiffness tests at low and intermediate temperatures but not at high temperatures. The second phase of the study was devoted to the damage responses of asphalt concrete. Permanent deformation (viscoplastic-viscodamage) was investigated at high temperatures (both uniaxial and triaxial), and the cyclic fatigue damage was studied at lower temperatures. The results are reported in three appended papers. A thorough investigation of the inherent damage interaction in asphalt concrete has been conducted in this thesis, which has not been done before. Based on the extensive literature review and our observations and experiments, the permanent deformation - fatigue damage interaction sequence dominates the asphalt concrete damage mechanism. This study applied both continuum damage mechanics (CDM) and dissipated energy (DE) approaches to assess the interaction. The existing prediction models have missed the interaction damage mechanism. It is observed that the myth of rutting-fatigue interaction is interrelated. This research confirms that rutting, apart from thermal cracking, is the cause of surface cracking. This observation further confirms the need for a unified damage model for accurate pavement performance prediction.

• Aurstad, J. & Taddesse, Ephrem (2016). Lærebok i vegteknologi. Statens Vegvesen, vegdirektoratet.
• Taddesse, Ephrem (2010). Development of roughness and rutting prediction models using data from road databanks. A comparative study of artificial neural networks and regression techniques. Norwegian University of Science and Technology. ISSN 978-82-471-2508-3.
• Taddesse, Ephrem (2009). Evaluation of pavement thicknesses using Ground Penetration Radar (GPR). NTNU.
• Taddesse, Ephrem (2007). Comparison of Field Measurements on Low-Volume Roads in Norway. NTNU.
• Taddesse, Ephrem (2007). Comparison of Field Measurements on Low-Volume Roads in Norway. NTNU.

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