الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Concrete-filled steel tube (CFST) is a creative innovation of steel-concrete composite construction that has recently been extensively utilized as an innovative sustainable alternative to
the existing structural bridge piers and building columns. These load-bearing components are likely to suffer from various accidental or intentional lateral impacts triggered by collision of vehicles, vessels, or debris from a nearby explosion. Increased industrialization and repeated terroristic attacks have escalated the risk of damage that can be very expensive to repair damages of collapsed structures that are often associated with the risk of human injury or even fatality. Therefore, it is necessary to design these members to withstand such impulsive loads. However, the response of CFST members when used as structural
columns subjected to a combination of lateral impact and axial load induced by the live and dead loads of building slabs or bridge decks has rarely been investigated in literatures. Concrete-filled steel tube (CFST) structure has been widely used in civil engineering
structures as it offers numerous structural benefits. Even though the (CFST) columns’ behavior
has been investigated intensively against axial and lateral impact loading, however there’s a lack
of knowledge on the response of (CFST) columns when filled with different types of concrete. Therefore, to close this gap, experimental and numerical studies were carried out to investigate
the performance of CFST members filled with four different types of concrete under the effect of lateral impact load. The concrete types were normal concrete (N.C), polypropylene fiber concrete
(P.F.C), steel fiber concrete (S.F.C) all with average cubic strength of Fcu=45 N/mm2 , and high
strength concrete (H.S.C) with Fcu=70 N/mm2 In heavily loaded members, the standard tubes’ sizes available in domestic market would not cover the required design size, hence emerged the need to fabricate the required sizes of pipes by welding. Consequently, the effect of using seam weld pipe instead of seamless pipe on the response of (CFST) under impact load was investigated in this study. Accordingly, twelve specimens were tested, divided into two groups. The first group consisted of eight specimens
fabricated from seam weld and seamless pipe with diameter of 114 mm, and the other group contained four specimens fabricated from seamless pipe with diameter of 88 mm. The parameters
studied were respectively, concrete type, steel pipe type, the length to diameter aspect ratio, along
with the confinement factor effect. The failure mode and local damages of the specimens were thoroughly investigated. A finite element analysis (FEA) model was then performed to simulate
the behavior of (CFST) members against lateral impact loading and validated with the corresponding experimental results. Wide range analyses of the (CFST) columns’ response against
lateral impact loading were then carried out using the validated FE models to examine the deformation and the energy dissipation of each concrete’s type.