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Title:	Punching shear strengthening of flat slabs using steel angle plates
Authors:	Hussein Riyadh Taresh (P91993)
Supervisor:	Mohd Yazmil Md. Yatim, Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Punching shear Structural systems Flat slabs
Issue Date:	22-Nov-2021
Description:	Punching shear failure in flat slab structural systems may be attributed to inadequate structural design, construction errors or change in the usage of the current structure with higher floor loads. This failure leads to severe human casualties, thus calling attention for the needs of proper detailing and design improvement. The thesis is concerned with the ultimate punching strength and behaviour of strengthened flat slabs particularly at the interior slab-column connections. The new strengthening technique was adopted by exploiting the combined action of both steel angle plates and high strength shear bolts. Shear bolts were installed in pre-drilled holes through the column sides and slab thickness. Eight angle plates were bonded around the column at the upper and lower slab surfaces using epoxy resin along with bolts and nuts fastening. Besides acting as vertical shear reinforcement, the primary functions of the bolts are to ensure a complete interaction by transmitting the vertical and horizontal forces between the angle plates and concrete surfaces, and to apply a high confinement pressure on the concrete mass around the column. Four large-scale flat slabs including a control specimen were constructed and tested to failure under shear load applied through the column in order to demonstrate the potential application of the proposed strengthening technique. Extensive measurement of displacements was made during the tests. Inelastic deformation particularly the disintegration at slab-column connection, crack pattern and overall behaviour of the test specimens were closely observed. The proposed technique has successfully changed the failure mode from pure punching shear to flexural, thus enhancing the load carrying capacity of the existing flat slabs ranging from 41% to 62% over that of the unstrengthened slab. Non-linear finite element analyses were performed using a general-purpose computer package ABAQUS for additional support to the test results and also for parametric studies. Important modelling aspects such as proper selection of elements, suitable material models and appropriate assignment of load and boundary conditions were accounted for. The numerical predictions were first validated against the experimental results in terms of ultimate load behaviour to confirm the modelling accuracy. Different configurations of angle plates, yield strengths of bolts, yield strengths of angle plates, spacing of bolts and number of bolts were accounted for to highlight their influences on load-deflection response, load-carrying capacity, stiffness of the slab system, level of ductility, energy absorption, and crack characteristic. The results of the finite element analysis revealed that the strength of both the steel plate and the shear bolts, as well as the space between the shear bolts, have a negligible effect on the ultimate strength of the enhanced slabs. In addition, the ultimate strength of the strengthened slab, based on the finite element analysis, ranged between 35% to 78% compared to the unstrengthened slab. Theoretical prediction of flexural capacity was also made by using a simple but reliable approach based on yield line theory. Comparison of results in terms of ultimate flexural strength shows good correlation within ±5% error in most cases, thus confirming the accuracy of the analytical method.,Ph.D.
Pages:	231
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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