الفهرس 
EXPERIMENTAL WORKOnly 14 pages are availabe for public view
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Abstract
Compared with other types of concrete bridges, the box girder
section is more ecconomical and aesthelically alternalive. Also. il
has high resislance t.o torsional loading. Earlier design melhods,
has the advantage of simplicily and closely modeling the behaviour
of box girder at service load and also, giving a valid lower bound
to the ultimate load condition. In addition, it cannot predict t..he
nonlinear behaviour of reinforced concrete box girder bridges up t..o
fai lure.
The main purposes of t..he present research work is t..o
investigate the effect of warping restraint.. at.. supports (end
d.iaphragl~) and the effect of changing reinforcement percenlages in
both the longitudinal and the Lransverse directions on the t..he
general deformational behaviour of R.C. box seclion girders t..hrough
the working and the ultimate load stages. In additions, the present
study ai~ to develop nonlinear mathematical model which can
praclically represent t..heaclual behaviour of such sLructures under
dead and live loads.
Therefore, an experimental-lheorit..ical study was conducted t..o
investigate lhe previous phenomena. The experimental phase of this
study was performed by t..eslingsix direct models of medium size of
R.C. box girder bridges which had the same dimensions but, wi th
different end conditions (warping restrained or unreslrained).
Also, t.hey had different. reinforcement. percentages in both Lhe
longitudinal. and Lhe Lransverse directions. All these girders were
tesled on a fixed end condition and’ loaded with an eccentric
conc~ntrated load at..midspan section to provide combined torsion,
bending and shear condition.
The theorit..ical study was performed using a Nonlinear Fininte
Element Method to study the previous effects t..aking into
corrsi der-at.Lorithe nonlinear stress- strain curve for concrete under
multiaxial slate of stress, cracking of concrete and yielding of
sleel. The finit..e element. resulls showed a good agreemenl with
experimenLal resulls.
The results of t..his exper iment..al-lheoritical study were
combined with available informalion t.o formulate some
recommendations for the analysis. design. const.ruction. ecconomy and the eval uat..ion of t.he exact st.iffness of R. C. box gi rder
bridges.