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Abstract
ensile and the compressive surraces were examined ark.
The rirst technique used :urraces with bonded steel plates.
was strengthening Factors studied in
both this
’einrorcement, shortening the tensile steel plate, the d.eel plaf.-e t.hickness. Furthermore, two dirrerent bonding nethod (epoxy & bolted connections) were used to bond the
steel plates to the concrete.
strengthening the tensile surrace with glued steel plates and strengthening the compressive surrace with cement mortar overlay.
strengthening the tensile surrace with bonded steel bars and strengthening the compressive surrace with cement mortar overlay.
The main conclusions obtained rrom the results or the experimental tests and the theoretical analysis are listed below :-
(i)-Generally, the three strengthening technique examined in this work have the rollowing errects .-
a-They increase the range or elastic behaviour.
b-They increase the rlexural stirrness and hence reduce the derlections, at all loading stages.
c-They increase the ultimate rlexural capacity.
(2)-When the slabs were strengthened on both surface with glued steel plates, the percentage increase in stirrness over the control slab ranged from 250 % to 465 % and the percentage increase in ultimate load ranged from 630 % to
1050 %. Ooth the stirrness and the ultimate load as the plate thickness increased.
overlay, the percentage increase in stiffness ranged from 170 % to 360 % and the percentage increase in ultimate load ranged from 490 % to 830 %. The stiffness and the ultimate
(4)-The slabs s~reng~hened on bo~h surraces wi~h glued s~ee\ plates can be regarded as a sandwich plate subJecterl
/”0 trans\’ersp. loads. the theoretlcal def lectlul\s, sLt’” i I\S
and ultimate loads had good agreement with Lhe experimental resul~s. However, ror similar cases or s~rengLhening, ~he
ul~ima~e momen~ carried by ~he pla~ed slab calcula~ed using Eq.(4-17).
reinrorcemen~ in tension and wiLh cemenL morLar overlay in compression, Lhe known limi~ s~a~e ~heory ror reinrorced concreLe design can be sa~israc~ory used ~o esLima~e Lhe ul~imate load capaciLy or the sLrengLhened slabs.
(6)-The used epoxy adhesive resin achieved good bond acLion beLween the steel plates and the concrete. A glue thickness or abouL 1.0 mm seams to be mos~ appropriaLe ror that purpose. However, adequa~e surrace prepara~ion is or prime impor~ance. When bonding s~eel bars ~o ~he concrete, ~he used epoxy can be used as a secondary bonding maLerial. A s\li~able thickness or underlay tha~ cov~rs ~he add0d s~eel seems ~o be necessary.