Short- and long-term analyses of composite beams with partial interaction stiffened by a longitudinal plate

Gianluca Ranzi 국제구조공학회 2006 Steel and Composite Structures, An International J Vol.6 No.3

This paper presents a novel analytical formulation for the analysis of composite beams with partial shear interaction stiffened by a bolted longitudinal plate accounting for time effects, such as creep and shrinkage. The model is derived by means of the principle of virtual work using a displacement-based formulation. The particularity of this approach is that the partial interaction behaviour is assumed to exist between the top slab and the joist as well as between the joist and the bolted longitudinal stiffening plate, therefore leading to a three-layered structural representation. For this purpose, a novel finite element is derived and presented. Its accuracy is validated based on short-and long-term analyses for the particular cases of full shear interaction and partial shear interaction of two layers for which solutions in closed form are available in the literature. A parametric study is carried out considering different stiffening arrangements to investigate the influence on the short-and long-term behaviour of the composite beam of the shear connection stiffness between the concrete slab and the steel joist, the stiffness of the plate-to-beam connection, the properties of the longitudinal plate and the concrete properties. The values of the deflection obtained from the finite element simulations are compared against those calculated using the effective flexural rigidity in accordance with EC5 guidelines for the behaviour of elastic multi-layered beams with flexible connection and it is shown how the latter well predicts the structural response. The proposed numerical examples highlight the ease of use of the proposed approach in determining the effectiveness of different retrofitting solutions at service conditions.

Short- and Long-term Analytical Solutions for Composite Beams with Partial Interaction and Shear-lag Effects

Fabrizio Gara,Gianluca Ranzi,Graziano Leoni 한국강구조학회 2010 International Journal of Steel Structures Vol.10 No.4

This paper presents an analytical model for the short- and long-term analysis of composite steel-concrete beams with partial shear interaction and accounting for shear-lag effects. The material properties of the concrete have been assumed to be timedependent and have been modelled by means of the algebraic methods while the remaining materials forming the cross-section have been supposed to behave in a linear-elastic manner. The global balance condition of the problem has been obtained by means of the principle of virtual work and, integrating this by parts, the governing system of differential equations and corresponding boundary conditions have been determined. Analytical expressions for both short- and long-term solutions have been derived and, to outline their ease of use, a number of case studies relevant for bridge applications have been proposed.

Generalised Beam Theory (GBT) for Stiffened Sections

G. Taig,Gianluca Ranzi 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.2

This paper presents an extension to the Generalised Beam Theory (GBT) approach to describe the response of prismatic thinwalledmembers stiffened by means of generic plate arrangements at different cross-sections along their length. Theconventional deformation modes to be included in the GBT formulation are obtained as the dynamic modes of a planar frame,which represents the cross-section. Two numerical procedures are implemented to account for the presence of the stiffeners. One approach identifies different sets of deformation modes for the unstiffened and stiffened sections, which are then combinedfor the member analysis. The second procedure relies on the use of constraint equations at the stiffened locations to be includedin the member analysis. For the cross-sectional analysis, a new mixed finite element is presented which incorporates theinextensibility condition usually adopted in the framework of the classical GBT, therefore simplifying the steps required for theevaluation of the conventional deformation modes. The proposed technique is applicable to open, closed and partially-closedstiffened sections. Two numerical examples are provided to highlight the ease of use of the method of analysis considering openand partially-closed sections, and their results are validated against those obtained with the commercial finite element softwareAbaqus.

Partial interaction analysis of multi-component members within the GBT

Alberto Ferrarotti,Gianluca Ranzi,Gerard Taig,Giuseppe Piccardo 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.25 No.5

This paper presents a novel approach that describes the first-order (linear elastic) partial interaction analysis of members formed by multi-components based on the Generalised Beam Theory (GBT). The novelty relies on its ability to accurately model the partial interaction between the different components forming the cross-section in both longitudinal and transverse directions as well as to consider the cross-sectional deformability. The GBT deformations modes, that consist of the conventional, extensional and shear modes, are determined from the dynamic analyses of the cross-section represented by a planar frame. The partial interaction is specified at each connection interface between two adjacent elements by means of a shear deformable spring distributed along the length of the member. The ease of use of the model is outlined by an application performed on a multi-component member subjected to an eccentric load. The values calculated with an ABAQUS finite element model are used to validate the proposed method. The results of the numerical applications outline the influence of specifying different rigidities for the interface shear connection and in using different order of polynomials for the shape functions specified in the finite element cross-section analysis.

Beam Tests of Composite Steel-concrete Members: A Three-dimensional Finite Element Model

Faham Tahmasebinia,Gianluca Ranzi,Alessandro Zona 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.1

Modern construction makes frequent use of composite steel-concrete beams for bridge and building applications. This paper describes a three-dimensional finite element model in which all components forming the composite member are modelled by means of solid elements. The proposed approach is developed using the commercial software Abaqus and is able to model the composite response without requiring information from push-out tests commonly performed to define the constitutive relationship for the shear connectors. All materials are assumed to behave in a nonlinear fashion. Contact between the elements is simulated using surface-to-surface and embedment techniques. The adequacy and accuracy of the proposed modelling approach are validated against experimental results available in the literature on simply-supported and continuous beam tests with both solid and composite slabs.

Non-uniform shrinkage in simply-supported composite steel-concrete slabs

Safat Al-Deen,Gianluca Ranzi,Brian Uy 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.2

This paper presents the results of four long-term experiments carried out to investigate the time-dependent behaviour of composite floor slabs with particular attention devoted to the development of non-uniform shrinkage through the slab thickness. This is produced by the presence of the steel deck which prevents moisture egress to occur from the underside of the slab. To observe the influence of different drying conditions on the development of shrinkage, the four 3.3 m long specimens consisted of two composite slabs cast on Stramit Condeck HPⓡ steel deck and two reinforced concrete slabs, with the latter ones having both faces exposed for drying. During the long-term tests, the samples were maintained in a simply-supported configuration subjected to their own self-weight, creep and shrinkage for four months. Separate concrete samples were prepared and used to measure the development of shrinkage through the slab thickness over time for different drying conditions. A theoretical model was used to predict the time-dependent behaviour of the composite and reinforced concrete slabs. This approach was able to account for the occurrence of non-uniform shrinkage and comparisons between numerical results and experimental measurements showed good agreement. This work highlights the importance of considering the shrinkage gradient in predicting shrinkage deformations of composite slabs. Further comparisons with experimental results are required to properly validate the adequacy of the proposed approach for its use in routine design.

Performance and Design of Shear Connectors in Composite Beams with Parallel Profiled Sheeting at Elevated Temperatures

Ling-Zhu Chen,Gianluca Ranzi,Shou-Chao Jiang,Faham Tahmasebinia,Guo-Qiang Li 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.1

This paper describes an extensive experimental and numerical study conducted to evaluate the thermo-structural response of shear connectors embedded in composite slabs with steel sheeting parallel to the steel beam, with particular focus on opentrapezoidal profiles. For this purpose, eight push-out tests were carried out at different levels of temperature. A threedimensional finite element model was developed in Abaqus and its accuracy was validated against the experimental measurements collected as part of this study. The model was then used to perform a parametric study to gain insight into the structural response at different temperatures. The experimental and numerical results were then used to evaluate the accuracy of available European guidelines for predicting the capacity of shear connectors at elevated temperatures (when embedded in composite slabs with the profiled sheeting parallel to the steel beam). Finally, a new design equation was proposed to calculate the degradation factor defining the resistance of shear connectors for different levels of temperature

Effects of Non-uniform Shrinkage on the Long-term Behaviour of Composite Steel-Concrete Slabs

Safat Al-Deen,Gianluca Ranzi 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.2

This paper presents the results of a series of tests aimed at investigating the development of shrinkage gradient considering slab samples of different concrete thicknesses and exposed to different drying conditions. For this purpose, two types of solid concrete specimens and two types of composite specimens were considered. Stramit Condeck HP® and PrimForm® profiles were used for the profiled sheeting of the composite samples. A total of twelve specimens were prepared and monitored for a period of four months. The experimental data was then used to further validate a previously proposed theoretical model capable of incorporating the effects of non-uniform shrinkage inside a composite slab. A simplified approach was also proposed to account for the occurrence of non-uniform shrinkage in routine design.

Analysis of the Shear Lag Effect in Composite Bridges with Complex Static Schemes by means of a Deck Finite Element

Fabrizio Gara,Graziano Leoni,Gianluca Ranzi 한국강구조학회 2008 International Journal of Steel Structures Vol.8 No.4

This paper presents the derivation of a finite element formulation for the analysis of composite decks accounting for partial interaction theory and shear-lag effects. The particularity of the proposed element, referred to as the deck finite element, relies on its ability to capture the structural response of complex static schemes, such as those specified for arch, bow-string and cable stayed bridges, while preserving the ease of use of a typical line element. For these particular bridge solutions, stress concentrations may be induced in the slab by the application of concentrated forces, i.e. due to the anchorage of prestressing cables or stays, or due to the presence of web members in arch bridges. The ease of use of the proposed deck finite element is outlined considering two case studies for which the calculated results have been compared against those obtained using a more refined model implemented using shell elements in a commercial finite element software.