MARCH 2015 MEETING
150 years of Advances in Civil Engineering Construction Materials from Conventional Concrete to Innovative FRP Composites
Speaker: Abdeldjelil "DJ" Belarbi, Ph.D.,P.E.; Hugh Roy and Lillie Cranz Cullen Professor. Tel No. (713) 743-1609.
Dr. Abdeldjelil Belarbi is Hugh Roy and Lillie Cranz Cullen Professor of Civil Engineering. He is actively engaged in a broad spectrum of structural engineering research areas, with primary contribution in the constitutive modeling, analytical and experimental investigation of reinforced and prestressed concrete structures. His research has also focused on seismic and wind structural performance of building envelopes, as well as smart structures and use of FRP composites with focus on the development of advanced materials and use of FRP for rehabilitation and strengthening of aging and deteriorated civil engineering infrastructure.
Dr. Belarbi has served as principal investigator or co-investigator on numerous research projects with a research expenditure of over ten millions US dollars, has published over 200 technical papers and had supervised over 45 MSCE theses and PhD dissertations. Dr. Belarbi is the recipient of numerous awards and honors. He is a Fellow of both the American Society of Civil Engineers (ASCE) and the American Concrete Institute (ACI). He is also very active (member and/or Chair) on several technical and educational and national committees within ACI, ASCE, ASTM, and TRB.
As an introduction to this topic Dr. Belarbi began with a short review of 150 years of Advances in Civil Engineering Construction Materials, from Conventional Concrete to Innovative FRP Composites. In this discussion, a saying was presented with regard to development of new2 materials and processes, “Look at the past, learn from successes and failures, and prepare for the future”.
Historical facts regarding construction materials and processes were addressed:
Development of “Building Codes” – the first was the “Code of Hammurabi”
Most buildings built about 1950 – nearing the end of their expected life, what to do – tear down? Not economically feasible? New construction? Old structures now required to service ever increasing loads and cycles of use. Examples -
Current challenges - World infrastructure Investment needs 2013-2030, Costs needed to replace or repair deficient structures is severe with many at the end of their expected lives
Addressing problem, experience and foresight – material suggestions “Traditional to FRP”
FRP – Aramid carbon or fiberglass reinforced – fibers or fabric matrix – light weight, high strength, corrosion resistant, flexible applications - Linear elastic, no yielding, higher ultimate strength, lower strain at failure
FRP 3-4 times stronger than steel, limitations – cost, anisotropy, brittle, etc
No corrosion but some environmental concerns regarding durability – temperature, moisture, etc.
Uses, bridge decks, Abutment panels, aircraft, auto’s, sports equipment, spacecraft, etc
FRP strengthening – Flexuural, axial, etc methods – steel plate bolted to concrete, member enlargement, FRP sheet – extra steel and concrete increases weight, FRP very light for essentially the same results, with installation time and complexity much less for FRP – by hand in one day – similar to painting, saturate FRP sheet with epoxy, apply to clean surface (certified applicator), roll out as for paint.
Application methods discussed. Applicators must be trained and certified and mfg’s specifications must be carefully followed. Showed various examples of applications.
Flexural strengthening of beams, apply to sides, top and bottom. – brittle so adding layers of FRP increases strength but reduces ductility (flexure).
Environmental reduction factors - .95 to .5 depending on CFRP (.95 -.85, AFRP,(.85 -.7) or GFRP (.75 - .5) Interior/exterior/aggressive conditions
Shear strengthening limited experimental knowledge base, limited testing/investigation, NCHRP Report 678, 2009-10 , on-going research, analytical models and design codes, Safety factors are arbitrary at this time.
Limitations on use because of possible types of failure and their impact on a structure, National Science Foundation projects. National Cooperative Highway Research Project “ASHTO” Code.