MSc Viva Voce

An MSc viva voce was performed on 21/01/2018 at the department of civil engineering for the Master student thesis Ali Duraid Hamdi that is titled as “PURE SHEAR PREFORMANCE OF STEEL-CONCRETE INTERFACE WITH DIVERSE TYPES OF SHEAR CONNERCTORS UNDER REPEATED LOADING“.

The viva committee members were assigned by the civil engineering department as follow:

Assist. Prof. Dr Ihsan Al-Sha’urbaf (Chairman)

Assist. Prof. Dr Ibraheem Saleem Ibraheem (Member)

Lec. Dr Ahmed Falih Al-Bayat (Member).

The student was supervised by Assist. Prof. Dr Laith Khalid Kamel.

The research abstract:

The present study represents a pioneer attempt to full the need to investigate the performance of the pure shear effect on the interface between concrete and steel containing shear connectors subjected to repeated loading up to fatigue with the effects of the main parameters. The studied parameters are the shear-connection distribution, the headed studs deformability and the grade of concrete embedment subject to a modied typical repeated fatigue load of displacement-control scheme to enhance the desirable mechanical properties and to have awareness of the undesirable ones. Accordingly, ten push-out prototypes with different properties have been experimentally studied under the effects of monotonous and irreversible periodic loadings separately. The latter has been modeled using a modied load history recommended by FEMA which has been amended to use only the positive loading scenario rendering it more representative for traffic loads on bridges, and appropriate to low cycle fatigue.
The ultimate shear capacity, the average anti-slip stiffness, the post-ultimate shear
weakening and the residual cyclic slippage index have been taken into consideration
within analysis, discussion and assessment of the experimental test results.
It has been found that elevating the grade of concrete embedment by double has sig-
nicantly increased the prototype shear resistance, the post-ultimate shear weakening
and the average-anti slip stiffness by 34%, 213% and 21.3%, respectively. Meanwhile,
reduction of the headed shear stud length by half has a main negative effect by lowering
the ultimate shear resistance by 12.4%, although it has revealed two substantial pos-
itive roles: reducing the unfavourite post-ultimate shear weakening property by 39%,
and increasing the desired average anti-slip stiffness by 37.7%. Furthermore, the effect
of decreasing the spacing between the headed studs by half (with keeping the total
cross sectional area of the headed studs unchanged) has caused slight decreases in the
average anti-slip stiffness.
In regard to the effect of load duration, the applied repeated load dened above
has caused reduction in the ultimate shear resistance ranging between 20% to 14%
in comparison with the monotonous loading performance .In opposite, that transfer
in load duration (from monotonous to repeated loading state) causes an increase of
16% in that property when using high grade of concrete embedment. In addition,
the average shear anti-slip stiffness is slightly reduced in the prototypes subjected
to repeated loading compared to their corresponding ones subjected to monotonous
loading. However, considerable reduction in that property of 14% is caused by the
high grade concrete embedment.
The repeated loading simulation performance of the tested push-out prototypes
has been predicted using the plastic-damage model for concrete through a presently
constructed nite element model by ABAQUS package. It was found that the ABAQUS
model accurately predicts the experimental response under repeated loading, where the
high agreement of the numerical model predictions with the experimental evidence is
a denite witness to the reliability of the numerical model.

The committee decided to award the student an MSc degree in civil Engineering with an excellent classification grade.