الفهرس 
CHAPTER (1): INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Hollow core slabs are a precast-prestressed concrete slabs used in the construction of floors in multi-story buildings, factories and bridges. In many projects it may be required to have an overhanging part of the slab to act as a cantilever. The main objective of this research is to study the behaviour of precast-prestressed hollow core slabs subjected to negative bending moments. An experimental test program was prepared to test six full scale precast-prestressed hollow core slabs with dimensions 4100 * 1200 * 160 mm. The specimens were tested as simply supported slab with cantilever under line load at its end up to failure. One slab was tested as control slab without strengthening and the other five slabs were strengthened with different materials. Two slabs were strengthened by GFRP sheets, one slab was strengthened by CFRP sheets, one slab was strengthened by GFRP bars and the remaining slab was strengthened by steel bars. The behavior of the tested slab were estimated in terms of first crack load, ultimate load, deflection, crack patterns, ductility ratio and the energy absorption. The hollow core slab strengthened by four layers of GFRP achieved the best structural results Numerical models based on the nonlinear finite element analysis were suggested to study the behavior of the tested slabs up to failure. The results of the developed numerical models with test results were presented. Good agreement was reached between the experimental and theoretical results.