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Obtaining an accurate simulation of the boundary conditions is very challenging but it is essential in order to represent the true behaviour of the whole structure in fire. In recent years, hybrid simulation has been emerging as an efficient and economical method for simulating realistic boundary conditions in the field of earthquake engineering. This technique can be used to study the load redistribution that may occur in a structural system as a result of locally elevated temperatures. In this paper, the fire-exposed element will be modelled in one analysis (a 3D model) and the rest of the structure in another analysis (a 2D model). This kind of sub-structuring enables the behaviour of the structural system as a whole to be studied. A hybrid simulation (HS) approach is presented and successfully implemented using the OpenFresco and OpenSees software. This approach enables the simulation of the correct restraint provided by the cold structure to the fire affected structural element. The HS analysis of a composite beam is compared with an unrestrained or simply supported version to highlight the difference in behaviour. Finally, the Cardington restrained beam test is modelled to demonstrate the potential of HS technique. Good agreement with the test results highlights that HS approach can be an effective method for studying the behaviour of the whole structural system. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of construction method (e.g. false skew, helicoidal and logarithmic method) on the mechanical behaviour and load carrying capacity of single span skew masonry arches. Simulations were performed with the three dimensional computational software, based on the Discrete Element Method of analysis. Each stone/brick of the masonry skew arch was represented by a distinct block. Mortar joints were modelled as zero thickness interfaces which can open and close depending on the magnitude and direction of the stresses applied to them. The variables investigated were the construction method, the angle of skew, the size of masonry blocks and the critical location of the live load along the span of the arch. At each skew arch, a full width vertical line load was applied incrementally until collapse. From the results analysis, it was found that for a skew masonry arch constructed using the false skew method, as the angle of skew increase, sliding between voussoirs in the arch increases and failure load decreases. However, for skew masonry arches constructed using the helicoidal and logarithmic method, as the angle of skew increases, the failure load increases. Three different characteristic failure modes were identified depending on the contact friction angle and the method of construction. These observations provide new insight into the behaviour and lead to suggestions for understanding the load carrying capacity and failure mode of skew arches. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive test database of concentric compression experiments on pultruded fiber-reinforced polymer (PFRP) specimens that failed in a global flexural buckling mode published in literature between 1969 and 2016. A new closed-form equation to determine the reduction factor for global flexural buckling of PFRP structural struts under axial compression is developed on the basis of the Ayrton-Perry formula and observed initial out-of-straightness of PFRP members measured by other researchers. Recognizing that data on initial imperfections may be unavailable, a second new empirical closed-form equation is derived based upon the experimental database. Validation of the two explicit expressions is performed by both comparison to experimental data and comparison with validated numerical simulations. In addition, the accuracies of the two proposed equations are compared with those of five closed-form solutions available in the literature; both results in more accurate predictions than the extant equations. Both new proposed equations can be conveniently used by structural engineers at the preliminary engineering design stage for accurately assessing the reliability and safety of composite structures under concentric compressive loading. [ABSTRACT FROM AUTHOR]

Recent studies at the Center for Infrastructure Protection and Physical Security (CIPPS) have focused on both active and passive protection, the definition and characterization of combined blast and fragment loads on structural elements, the influence of Ultra High Performance Concrete (UHPC) on the behavior of structural elements, and evaluating analysis approaches for progressive collapse assessment. Those studies have highlighted important issues that have not been sufficiently addressed previously, and this paper is aimed at describing the observations from the CIPPS studies that could be used to treat such difficult issues. [ABSTRACT FROM AUTHOR]

Abstract: Previous studies of pounding responses of bridge structures to seismic loadings are usually based on the point to point pounding assumption by using the simplified lumped mass model or beam–column element model. It has been found these simplified models can be used to calculate bridge pounding response with consideration of only the longitudinal excitation. In a real bridge structure under seismic loading, pounding could take place along the entire or part of surfaces of the adjacent segments. Moreover, torsional response of the adjacent decks owing to the asymmetric deck or induced by spatially varying transverse ground motions at multiple bridge supports may result in eccentric poundings between adjacent bridge decks. A detailed 3D finite element model is necessary to consider the surface to surface and torsional response induced eccentric poundings and the corresponding damage. This paper performs numerical simulations of pounding damage between bridge girders and between bridge girder and the corresponding abutment of a two-span simply-supported bridge to spatially varying ground motions based on a detailed 3D finite element model by using the explicit finite element code LS-DYNA. The dislocation and unseating potentials of the bridge are also modelled. The bridge components including the bridge girders, abutments, pier, bearings, longitudinal reinforcement bars and stirrups are included in the model. The non-linear material behaviour including the strain rate effects of concrete and steel rebar are considered. The spatially varying ground motions are stochastically simulated. The damage mechanism of the bridge under spatially varying seismic loadings is examined. Numerical results show that the method adopted in the present paper can realistically capture the seismic induced damage of bridge structures. [Copyright &y& Elsevier]

The present paper quantifies the adverse effects that can generate rebar section loss, induced by corrosion, especially on the bearing capacity of nuclear power plant cooling towers under extreme wind conditions. Numerical simulations, taking into account, appearance of concrete cracks and their evolution via an appropriate material concrete law and rebar’s yielding, are conducted. Different levels of corrosion are considered which are approximated by rebar section loss. Finally, to restore the integrity of these structures, composite material such as a carbon fiber reinforced plastic (CFRP) layer is modelled. The enhancement of the bearing capacity of the damaged structure compared to the undamaged structure is evaluated in the pre- and post-cracking regime. The main conclusion drawn from the numerical results is that the CFRP reinforcement is very effective for improving the integrity of RC cooling tower shells even when the latter present an advanced corrosion rate. [ABSTRACT FROM AUTHOR]

Long-span bridge traffic loading is governed by congestion. Although congestion can take various forms, most previous studies consider only a queue of vehicles. In this paper, traffic micro-simulation is used to generate several congested traffic scenarios on a two-lane same-direction roadway passing over two long-span bridges. To this end, an acknowledged car-following model is coupled with a lane-changing model. Different traffic compositions and several congestion patterns are analysed in relation to their traffic features and influence on bridge loading. It is found that: (a) slow-moving traffic may be as critical as the full-stop condition, depending on the span length; (b) critical long in-lane truck platoons form mainly at moderate inflows, typically occurring outside of rush hours; (c) the truck distribution between lanes has a limited effect on the total loading; (d) the presence of cars has a strong indirect influence on loading through their interaction with trucks. The methodology and the findings have relevance for computing a more accurate traffic loading for long-span bridges. [ABSTRACT FROM AUTHOR]

This paper presents the results of a series of tests on timber shear walls exposed to simulated flooding and drying. Load tests were conducted on three wall types; control, wet and restored. The mechanical properties of each of these wall types were compared. It was found that there were significant losses in mechanical strength for the wet and restored walls tested. For wet walls, ultimate strength was reduced by 20% and for the restored walls ultimate strength was reduced by 25%. The restored walls were observed to fail due to sheathing buckling caused by swelling of the OSB during simulated flooding. This failure mode following flooding and restoration is one that is not currently accounted for by design codes or designers. [ABSTRACT FROM AUTHOR]

In this paper, the buckling response of glass panels linearly supported along the top and bottom edges, under the action of in-plane shear loads, is investigated by means of analytical and Finite-Element (FE) methods. The typical buckling behaviour is first assessed in the hypothesis of fully neglecting the possible deformability contribution of adhesive linear supports, while successively the effects of linear, flexible sealant joints on the overall structural response of the same panels are also properly taken into account and highlighted. Based on extended parametric FE linear buckling and nonlinear incremental simulations, the influence of initial geometrical imperfections with various shapes and amplitudes, adhesive stiffnesses and glass types is investigated, both for monolithic and laminated glass panels. In the latter case, the accuracy of an equivalent thickness approach derived from early contributions is also demonstrated. Analytical approximating curves are proposed for the fitting of numerically derived buckling coefficients, so that they could represent a practical tool in the calculation of the expected Euler’s critical load. A normalized buckling curve for ideally simply supported glass panels under in-plane shear loads is finally recalled from past research projects and proposed as a rational design method for the examined loading and boundary condition. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of flexible culverts – often referred to as soil–steel composite bridges (SSCB) – when constructed in sloping topography. A number of 2D finite element models were created to simulate three case studies compromising two pipe arches and one high profile arch. The models were generated to investigate the effect of different surface slopes for different depths of soil cover. The aim was to understand and perceive the change of sectional forces in the structure with respect to slope increase under different soil covers. In addition, the effect of structure presence in the soil was also investigated in terms of soil stability. The results enable to realize the susceptibility of such structures to low heights of soil cover when built in sloping environment, which is seen in the incremental change in displacements and sectional forces, specially the bending moments. It is also found that the geometrical aspects of the profile shapes have more pronounced effect on their performance when introducing steeper slopes. The safety factor of soil stability is found to decrease when introducing such structures in the soil. [ABSTRACT FROM AUTHOR]

This paper presents the results of an extensive numerical and analytical study to re-investigate the mechanism of load introduction into concrete-filled tubular column through shear connection. The new mechanism of load introduction revealed from this research indicates that the shear load from the connection is introduced through the column length above and within the connection. This is different from the currently assumed mechanism of load introduction from underneath the connection. In fact, a simple free-body diagram analysis would demonstrate that the currently assumed load introduction mechanism is not possible. The results of the numerical simulations also indicate that the load introduction length above the connection is unlimited and can be as long as the entire column height. Based on the new load introduction mechanism and the numerical simulation results, the maximum amount of load introduced into the concrete core can be calculated as the bond strength multiplying the entire steel tube/concrete core contact surface area for the entire column length above and including the connection. Under the new load introduction mechanism and using representative values of column dimensions and concrete cylinder strength, it has been demonstrated that complete load introduction can be achieved in almost all practical arrangements of concrete filled tubular construction. [ABSTRACT FROM AUTHOR]

Abstract: Currently, guidelines for safely using shipping containers for building applications do not exist. The shipping container’s structural integrity, modification properties, foundation limits, building code regulations, and reinforcing limits are mostly unknown. As a result, this research begins the investigation of shipping containers’ structural limitations thus aiding the development of container building construction and design requirements. The main research objective is to develop structural guidelines for International Organization for Standardization (ISO) shipping containers used for non-shipping applications. This paper provides insight into the ISO shipping container’s structural strength which is further investigated using finite element computer modeling. The finite element analysis shows how both modified and unmodified container models respond under given loading scenarios. The loading scenarios incorporate the effect of gravity and lateral loading, and the computer simulations demonstrate the effectiveness of the container walls and roof to resist the loads. Structural engineering considerations, foundations, and connections for shipping containers used in building applications are presented. [Copyright &y& Elsevier]

Abstract: A new glass fibre reinforced polymer (GFRP) sandwich panel has been developed for flooring system. The new panel is made of modified phenolic core and E-CR glass skins. This paper presents the results of the experimental behaviour and the non-linear finite element analysis (FEA) of the GFRP sandwich panel. The experimental works investigate the behaviour of the GFRP sandwich panel, skin–core interaction, and core behaviour. A non-linear finite element model was developed to simulate the behaviour of the skin–core interaction, and the model was verified by comparing the results with those obtained from testing. The non-linear FE model was applied to a single span GFRP sandwich floor panel under point load test. The GFRP sandwich floor panel demonstrated a linear behaviour under point load. The results of the numerical simulations show a good agreement with the experimental results. [Copyright &y& Elsevier]

Abstract: This paper presents the second part of an experimental investigation carried out on a construction system based on completed in-situ sandwich panels with non-shear connectors, concerning the study of floor sandwich panels. Four-point flexural tests were carried out on several full-scale panel specimens with different slenderness ratios in order to study the behaviour of panels under vertical loads. Additionally, wall–floor nodes with different connection details were tested to analyze the effective degree of the rotational restraint of different realistic nodes. Furthermore, a loading test on the floor of a full scale 3D mock-up entirely built with sandwich panels was carried out to investigate the service and ultimate behaviour of a real floor. The most significant load-displacement diagrams for increasing load are illustrated and the failure modalities are discussed. The semi-composite behaviour of the panels, guaranteed by the internal layer of polystyrene and the reinforced concrete beams at the panel ends, is highlighted. The effects of the wall–floor connection and the bi-dimensional behaviour of the floor are also evaluated. Finally, some numerical simulations are performed with non-linear finite element models and some useful design indications are given. [Copyright &y& Elsevier]

Abstract: Because of evident aesthetic, lighting and architectural advantages, glass curtain walls are largely used to clad modern buildings. Since these elements are considered to constitute purely architectural systems, they are essentially designed to resist loads acting orthogonally to the plane of the façade (e.g. wind loads). Contrarily, glass elements are frequently used as structural components able to sustain in-plane loads (e.g. columns, stiffening fins, beam elements, stairs, etc.), thus to preserve their integrity a buckling verification could assume great importance. In order to overcome these problems, an analytical formulation is proposed for the estimation of the buckling resistance of flat laminated glass panels under in-plane compression or shear. Two different design approaches are taken into account and compared: the first one directly derives from the theory of sandwich panels, whereas the second one is based on the approximate concept of equivalent thickness. As discussed in the paper, this last approach constitutes a useful design expedient for the deformability and resistance check of buckled laminated panels under in-plane compression or shear, in presence of different boundary conditions. Since the resistance of such brittle elements directly depends on the level of connection between the glass panes offered by the interlayer, the effects of possible temperature and time-loading variations are highlighted. The obtained analytical results are in agreement with sophisticated numerical simulations. [Copyright &y& Elsevier]

Abstract: This paper deals with the shape generation of structural shells within the field of Conceptual Design. Both physical models and computational simulations are presented and discussed. The design is based on the biological principle of homeostasis which states the following: When an external agent attacks the structure, the latter defends itself “intelligently” to recover its bearing capacity. Here, heat is the external agent used to cause the model material degradation. Thus the model adopts a more appropriate structural shape in order to continue to resist loads. The physical experiment is carried out by introducing a Polymethyl Methacrylate (PMMA) plate in an oven with defined boundary conditions and loads. The virtual simulation is performed using a finite element software. A thermal elasto-plastic material model is included to represent the PMMA behavior. A comparison between the shapes found with both approaches is presented. Notwithstanding the diversity of the methods and uncertainties in the material characterization the match is more than acceptable. The numerical simulation may constitute a low cost complement to shell form-finding using the Homeostatic Model Technique. Additionally, the obtained shape is employed as the geometry of a structural shell and both, experimental and finite element stress analyses are performed, yielding a quasi-membranal behavior. [Copyright &y& Elsevier]

Abstract: When formulating an approach to assess bridge traffic loading with allowance for Vehicle-Bridge Interaction (VBI), a trade-off is necessary between the limited accuracy and computational demands of numerical models and the limited time periods for which experimental data is available. Numerical modelling can simulate sufficient numbers of loading scenarios to determine characteristic total load effects, including an allowance for VBI. However, simulating VBI for years of traffic is computationally expensive, often excessively so. Furthermore, there are a great many uncertainties associated with numerical models such as the road surface profile and the model parameter values (e.g., spring stiffnesses) for the heavy vehicle fleet. On site measurement of total load effect, including the influence of VBI, overcomes many of these uncertainties as measurements are the result of actual loading scenarios as they occur on the bridge. However, it is often impractical to monitor bridges for extended periods of time which raises questions about the accuracy of calculated characteristic load effects. Soft Load Testing, as opposed to Proof Load or Diagnostic Load Testing, is the direct measurement of load effects on bridges subject to random traffic. This paper considers the influence of measurement periods on the accuracy of soft load testing predictions of characteristic load effects, including VBI, for bridges with two lanes of opposing traffic. It concludes that, even for relatively short time periods, the estimates are reasonably accurate and tend to be conservative. Provided the data is representative, Soft Load Testing is shown to be a useful tool for calculating characteristic total load effect. [Copyright &y& Elsevier]