This thesis examines the effects of reinforcement ductility on the strength and ductility of reinforced concrete slabs. An extensive experimental program examining the ultimate strength, ductility and failure mode of one-way and two-way reinforced concrete slabs is described and the results are presented and analysed. A numerical finite element model is developed and calibrated using the experimental data. The model is described and shown to accurately simulate the collapse load behaviour of reinforced concrete slabs containing reinforcement of any ductility class, including Class L welded wire fabric. Parametric studies using the numerical model to assess the effects of reinforcement ductility on structural behaviour are also presented and recommendations are made on the minimum reinforcement ductility levels appropriate for use in suspended slabs. The experimental and numerical tests investigated slabs with different types of boundary conditions (simply supported and continuous one-way slabs, corner-supported single panel two slabs and edge-supported two-way slabs), support settlement, steel reinforcement ratio, steel uniform elongation (su), steel ultimate to yield stress ratio (fsu/fsy) and rectangularity aspect ratio in the two-way slabs. In total, thirty one slabs were tested. The one-way slabs included four simply supported slabs, seven continuous slabs, and five continuous slabs with support settlement. The two-way slabs included eleven square and rectangular corner-supported slabs and four rectangular edge-supported slabs. The one-way simply-supported slabs were 850mm in width, 100mm in depth and 2,500mm in length. The continuous one-way slabs were 850mm in width, 100mm in depth and 4,350mm in length. The continuous one-way slabs and subjected to support settlement were 850mm in width, 120mm in depth and 6,300mm in length. The square two-way slabs had an edge length of 2,400mm and a depth of 100mm and the rectangular two-way slabs had width of 2,400mm, a length of 3,600mm and a depth of 100mm.

Thesis (Ph.D.)--Royal Institute of Technology (Stockholm, Sweden), 2005. / "ISRN KTH/BKN/B-80-SE." "Dept. of Civil and Architectural Engineering, Division of Structural Design and Bridges, Royal Institute of Technology, Stockholm. " Includes bibliographical references. Available from the Royal Institute of Technology (Sweden) Library as a .pdf document http://www.lib.kth.se/main/eng/

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Yes / This paper presents an experimental investigation of demountable reinforced concrete slabs using dry connections between reinforced concrete slab elements. The test specimens comprised six full-scale reinforced concrete slabs; one control slab monolithically cast, while the other five slabs were produced with mid-span demountable dry connections. The slab elements were cast separately and assembled using top and bottom steel plates joined to each side of the slab element by high tensile steel bolts with or without a shear key and embedded steel block. Theoretical analysis of the behaviour of the demountable slabs tested in comparison with the control specimen was also conducted. The test results showed that using a dry connection consisting of a shear key at the assembled section is the most effective technique in terms of moment resistance, deflection, and flexural stiffness. On the other hand, the dry connection with embedded steel blocks failed prematurely because of stress concentration at the block edges. The moment capacity and deflection predictions of demountable slabs have reasonably correlated with the experimental results but required additional calibrated data from experiments. / This work was supported by an Institutional Links grant, ID 414633184, under the Newton-Kâtip Çelebi Fund partnership. The grant is funded by the UK Department for Business, Energy and Industrial Strategy and TÜBİTAK – Scientific and Technological Research Council of Turkey and delivered by the British Council. For further information, please visit www.newtonfund.ac.uk.

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no / The design of multi-storey buildings in the UK, in the past, considered steel and concrete structures in isolation. Today, designers utilize the combined properties of steel and concrete in the form of composite or hybrid structures as a more attractive efficient alternative. Designers of steel structures acknowledge that the presence of concrete slabs may be designed compositely with steel beams in order to increase both flexural strength and stiffness at virtually no extra cost, except for the headed shear studs. The use of composite construction with precast hollowcore slabs has become one of the most popular construction methods in the UK. Currently, design of composite construction is covered by BS5950, Part 3, but will soon be replaced by the new European Standard, Eurocode 4. However, design of composite construction with precast hollowcore slabs is currently outside the provisions of this new code. In this paper, an overview of the Eurocode 4 structure and its contents are first presented and some of the particular issues that affect this new form of construction will be given. Design guidance using the Eurocode methodology will also be presented.

No / Composite structure incorporating steel beams and precast hollowcore slabs is a recently developed composite floor system for building structures. This form of composite construction is so far limited to simple beam-column connections. Although the concept of semi-rigid composite joints has been widely research in the past, most of the researches have been carried out on composite joints with metal deck flooring and solid concrete slabs. Research on composite joints with precast hollowcore slabs is rather limited. As the construction industry demands for rapid construction with reduction in cost and environmental impacts, this form of composite floor system, which does not require major onsite concreting, has become very popular among the designers and engineers in the UK. In this paper, full-scale tests of beam-to-column semi-rigid composite joints with steel beam and precast hollowcore slabs are reported. Based on the tests data; the structural behaviour of these semi-rigid composite joints is discussed together with numerical and finite element modelling. Through parametric studies, an analytical model for the semirigid composite joints is proposed and is verified by both the experimental data and finite element model; and good agreement is obtained.

<p dir="ltr">Link slabs offer a cost-effective solution for eliminating deck expansion joints in multi-span bridges. A link slab is the cast-in-place concrete portion that makes only the deck slab continuous while the girders remain simply supported between two adjacent deck spans. By closing the expansion-joint opening, link slabs can reduce the costs of repairing and rehabilitating leaking joints and improving the bridge riding surface. Link slabs are designed to resist the bending moments imposed by girder end rotation due to live load plus impact, assuming the bridge spans are simply supported at the joints. The continuity provided by the link slab under live load is neglected, based on the assumption that its stiffness is lower than that of the girders. Furthermore, structural elements capable of load transfer (e.g., stirrups and shear stud connectors) within the limits of the deck joint elimination are often removed to reduce induced stresses in the link slab. A bond breaker is placed between the top of the girders and the bottom of the link slab to mitigate stresses. The debonded length, typically set at 5% of each span length, defines the total length of the link slab. Practices may vary among states, such as Indiana, where a composite action between the link slab and supporting girders is maintained. </p><p dir="ltr">However, increased cracking observed in the field is the primary concern about debonded link slabs. Once the cracks form, they allow the entrance of corrosive chemicals and debris, causing deterioration of concrete bridge components. The causes of the increased cracking and resulting leakage at the link slabs have been associated with the limitations of the existing design approaches in considering the effects of thermal loads and support conditions. This study presents a comprehensive finite element analysis to evaluate the behavior of bridge deck link slabs under the combined effect of traffic loads and vertical temperature gradients. The link slabs are subjected to HL-93 loading and temperature gradients following AASHTO LFRD Bridge Design Specifications. A finite element model of the Plott Creek Bridge in Haywood country in North Carolina, instrumented by Wing & Kowalksy (2005), is developed using ABAQUS/Standard software. The numerical model is validated against test data from previous studies available in the literature.</p><p dir="ltr">The results of the numerical investigation reveal that vehicular traffic loading is the primary factor contributing to the cracking of the link slabs. However, vertical temperature gradients are also identified as significant factors inducing stresses within the link slabs. Specifically, the combination of live load and a negative temperature gradient is the most influential loading condition contributing to cracking at the top surface of the link slabs. It is important to note that the rotation of the girder ends due to live load induces a negative moment (tension at the top) on the link slab. A negative temperature gradient, where the temperature on the top deck surface is lower than that on the web of the beams, results in an additional negative moment on the link slab due to its addition to the rotation from the live load. The temperature gradients are observed to increase the girder end rotation obtained from live load analysis for simply supported beams by approximately 20% in the range of parameters considered in the present study. This finding underscores the importance of considering temperature effects in link slab design to ensure structural integrity. </p><p dir="ltr">Furthermore, parametric studies are conducted to assess the impact of various factors such as girder support conditions, span length, debonded zone length, and material properties on crack initiation in link slabs. The analyses show that the primary factors affecting the tensile stress developed in the link slabs are the span length and the girder support conditions. This highlights the importance of considering these factors when designing link slabs. Based on the findings, design recommendations are proposed to enhance the current practices for link slab design. These recommendations include considering temperature gradients alongside live loads, adopting distributed bar spacing for crack control, and incorporating an allowable stress limit of 0.60fy for steel reinforcement following AASHTO LFRD Bridge Design Specifications. Given that link slabs exhibit cracking under service conditions, it is advisable to determine the amount of longitudinal tension reinforcement based on cracked section analysis rather than simply providing the minimum reinforcement. Furthermore, incorporating a debonded zone within 5% to 7.5% of the span length at each side of the link slab is recommended to reduce stresses. The use of roller support is not recommended for link slab applications, while hinge supports can be effective if the span length is less than 15~m (50~ft.). </p>