Eurocode Standards Research Articles

The Effect of Openings on Stress Distribution in Glass Beams – Dependence on Diameter of Openings

Presented paper describes the behaviour of simply supported single ply glass beam with discontinuities in its geometry. Discontinuity is introduced by four openings symmetrically placed over the beam. This type of simplified structure represents cut out of real constructions where similar glass components are used as primary load bearing structures supporting glazing of roofs or decks of pedestrian bridges. The main focus of this article is in research of stress distribution around openings and how different diameter of a hole influences stresses in its close proximity. As Eurocode standards for glass structures are still not codified and most of the nowadays literature only provide suggested diameters of holes based on the thickness of the glass pane, this paper will provide the future designers of glass load bearing structures with closer look at stress distribution around mentioned area. In order to bring those informations to theirs seekers, both experimental analysis and numerical analysis together with parametric study were used.

Out-of-plane buckling resistance of rolled steel H-section beam-columns under unequal end moments

A novel analytical model is proposed for establishing design criteria based on the decomposition of the in-plane deformation and out-of-plane stability states. First part of this study considered the in-plane buckling resistance of beam–columns. This study uses the results from Gizejowski et al. [42] to develop an analytical model for the inelastic out-of-plane buckling resistance of beam–columns subjected to a moment gradient. The elastic flexural–torsional buckling solution is combined with the in-plane solution via the generalised Ayrton–Perry model. In order to unify the recommendations for the resistance evaluation of beams, columns, and beam–columns, the model is customised to conform to the standard Eurocode technique of modelling buckling resistance of steel elements in compression or bending about the cross-sectional axis with the greater moment of inertia. As a result, the out-of-plane resistance interaction curves, expressed in dimensionless coordinates, which describe the beam–column flexural–torsional buckling resistance and consider lateral–torsional buckling effects, are obtained. The results of finite element simulations are used for the verification of the developed analytical formulation. Two numerical techniques of imperfection modelling are used: an equivalent geometric imperfection approach with the Maquoi–Rondal generalised initial imperfection and an approach that individually considers geometric and material imperfections. The results obtained from the proposed analytical model and those obtained using the Eurocode design criteria and other recent analytical proposals are compared. Finally, concluding remarks and directions of future studies are also presented.

First experiences with concrete screw anchors as postinstalled shear reinforcement in concrete bridges

AbstractDue to growing traffic volume and more restrictive design standards, structural engineers require new strengthening systems for concrete structures. Especially the level of calculated shear reinforcement has increased with the introduction of the Eurocode standards. Therefore, new methods to improve the shear strength of existing structures are needed. Concrete screws are used as a fastening system in concrete. Due to the mechanical connection, a very robust bond between the reinforcement element and the concrete is given. The new idea is to use these anchoring elements as postinstalled shear reinforcement. To show the usability and enhancements of the new method, several test series with concrete girders have been performed at the University of Innsbruck. Using concrete screws in several different configurations all test beams showed a remarkable increase in shear‐load capacity. With a new design approach derived from the test results it was possible to apply the new system to several pilot‐projects. One slab bridge built in the 1970s was strengthened to the load level according to Eurocode. Another pilot‐project was realized at a railway bridge with a two span concrete box girder. This bridge was built with tendons vulnerable to stress corrosion cracking. To ensure a ductile failure, strengthening was necessary which was realized with concrete screws under ongoing traffic on and underneath the bridge. Currently a shear strengthening of a city tunnel in the central area of Munich is planned. In the roof slab about 7000 concrete screws are projected to be installed as shear and bending strengthening system.

Wind loading on shell structures on example of CICIND and Eurocode standards

Wind loading on shell structures on example of CICIND and Eurocode standards

Progressive Collapse Assessment: A review of the current energy-based Alternate Load Path (ALP) method

The Alternate Load Path (ALP) is a useful method that has generated a considerable recent research interest for the assessment of progressive collapse. The outcome of the ALP analysis can be assessed either using the force-based approach or the energy-based approach. The Unified Facilities Criteria (UFC- 4- 023-03) of progressive collapse guideline - have outlined that the force-based approach can either be analysed using static or dynamic analysis. The force-based approach using static analysis is preferable as it does not require a high level of skill and experience to operate the software plus no effort is required in scrutinising the validity of the analysis results output. However, utilising the static approach will eliminate the inertial effect in capturing the actual dynamic response of the collapsed structure. In recent years, the development of the energy-based progressive collapse assessment is attracting widespread interest from researchers in the field; as the approach can produce a similar structural response with the force-based dynamic analysis by only using static analysis. Most of the current energy-based progressive collapse assessments are developed following the requirements which are given in the progressive collapse guidelines provided by the Unified Facilities Criteria. However, little attention is given to the development of the energy-based approach using the Eurocode standards as a base guideline. This article highlights the merits of utilising the energy-based approach against the force-based approach for a collapsed structure and explains the collapse mechanism of a steel frame in the perspective of the energy concept. The state of the art of energy-based progressive collapse assessment for a structural steel frame is reviewed. The comprehensive review will include insights on the development of the energy-based method, assumptions, limitations, acceptance criterion and its applicability with the European standards. Finally, potential research gaps are discussed herein.

PROJEKAT VIŠESPRATNE ZIDANE ZGRADE PREMA EVROKODU I UPOREDNA ANALIZA DOMAĆIH I EVROPSKIH STANDARDA ZA ZIDANE ZGRADE

U radu je prikazan projekat višespratne zidane zgrade spratnosti (Pr + 3) na području Novog Sada, prema Evrokod standardima. U drugom delu rada prikazana je uporedna analiza proračuna zidanih zgrada prema domaćim propisima i Evrokodu.

Experimental and numerical study on compressive performance of perforated brick masonry after fire exposure

SummaryThis paper discusses the compressive performance of perforated brick masonry after fire exposure. Compressive strength tests of the mortar, clay perforated brick, and perforated brick masonry specimens were performed in accordance with ISO834 fire tests of different durations. The temperature distribution of the masonry materials and specimens was simulated using the finite element software ABAQUS, with the thermal parameters of masonry materials recommended by European standard Eurocode 6 and related literature. The compressive strength reduction factors of mortar and clay perforated brick exposed to different fire durations were calculated via the layered method suggested by European standard Eurocode 1. In addition, the compressive strength reduction factors after cooldown were obtained from the experimental data of the masonry materials, and by considering further reductions in the compressive strength after cooling from high temperatures. Experimental data of the masonry specimens were compared with the numerical results obtained using the reduction factors proposed in this work. The comparison revealed an overall acceptable approximation. Thus, the method presented in this paper can be used to evaluate the residual capacity of masonry structures after fire.

Probabilistic Verification of Structural Stability Design Procedures

Introduction: This contribution presents a comparison of three methods of the statistical computation of the design load-carrying capacity of a steel plane frame. Two approaches of the European Standard Eurocode 3 and one stochastic approach are applied. The stochastic approach takes into account the random influence of all imperfections and can be applied to the reliability verification of design according to Eurocode 3. Methods: The columns and beams in the steel frame are modelled with beam elements using the stability solution with buckling length and the geometrically nonlinear solution. The stochastic computational model is based on the geometrically nonlinear solution and on the random influence of initial imperfections, whose random samplings are simulated using the Monte Carlo method. Results and Conclusion: The design load-carrying capacity of the steel plane frame computed using the stability solution with buckling length is in good agreement with the stochastic solution in which the design value is calculated as 0.1 percentile. On the contrary, the geometrically nonlinear solution according to Eurocode 3 gives the lowest (safest) values of design load-carrying capacity.

Experimental Campaign and Analysis on Double-Shear Wooden Connections

Abstract The presence of water in wooden elements is very important because it represents the key in the determination of the resistances of a wooden sample. The influences of the environmental conditions like temperature, relative humidity, wind, rain are constantly changing wood properties. The paper presents the different types of water that are found in a wooden piece together with experimental results on the displacement of double-shear wooden connections with wooden dowels that have been modified in two pre-established environments. The moisture content has been changed from 12% natural moisture of wood in normal building conditions to 8% and 16% for wood that is found in different climatic conditions. The experimental results are then compared with numerical calculations from the international standard Eurocode 5.

Numerical analysis on the behaviour of reinforced concrete frame structures in fire

Numerical approach using finite element method has been used to evaluate the behaviour of reinforced concrete frame structure subjected to fire. The structure is previously designed in accordance with Eurocode standards for the design of structures for earthquake resistance, for the ductility class M. Thermal and structural response are obtained using a commercially available software ANSYS. Temperature-dependent nonlinear thermal and mechanical properties are adopted according to Eurocode standards, with the application of constitutive model for the triaxial behaviour of concrete with a smeared crack approach. Discrete modelling of concrete and reinforcement has enabled monitoring of the behaviour at a global, as well as at a local level, providing information on the level of damage occurring during fire. Critical regions in frame structures are identified and assessed, based on temperatures, displacements, variations of internal forces magnitudes and achieved plastic deformations of main reinforcement bars. Parametric analyses are conducted for different fire scenarios and different types of concrete aggregate to determine their effect on global deformations of frame structures. According to analyses results, the threedimensional finite element model can be used to evaluate the insulation and mechanical resistance criteria of reinforced concrete frame structures subjected to nominal fire curves.

Glued laminated timber and steel beams

PurposeThis paper aims to compare glued laminated timber and steel beams with respect to structural design, manufacturing and assembly costs and the amount of greenhouse gas emissions.Design/methodology/approachThis paper presents structural design requirements in conformance with EN 1993: Eurocode 5 and Eurocode 3. With the help of these standards, expressions are derived to evaluate the design criteria of the beams. Based on the results of life-cycle analysis, the economic properties and environmental impact of the two types of beam are investigated. In this paper, the effect of beam span on the design values, costs and carbon dioxide emissions is analysed when investigating aspects of the structural design, economy and environmental impact. Different cross-sections are chosen for this purpose.FindingsThe study shows that the glued laminated (abbreviated as “glulam”) beams have a smaller tendency to lateral torsional buckling than the steel beams, and that they can be cheaper. From an environmental point of view, glulam beams are the more environmentally friendly option of the two beam materials. Furthermore, glulam beams may have a direct positive effect on the environment, considering the carbon storage capacity of the wood. The disadvantage of glued wood is that larger dimensions are sometimes required.Research limitations/implicationsWind load and the effect of second-order effects have not been considered when analysing the static design. Only straight beams have been studied. Furthermore, the dynamic design of the beams has not been investigated, and the bearing pressure capacity of the supports has not been analyzed. We have investigated timber beams with a rectangular cross-section, and steel beams of rolled I-sections, known as “HEA profiles”. The cost analysis is based mainly on the manufacturing and assembly costs prevalent on the Swedish market. The only environmental impact investigated has been the emission of greenhouse gases. The design calculations are based on the European standards Eurocode 5 and Eurocode 3.Practical implicationsTo achieve sustainability in construction engineering, it is important to study the environmental and economic consequences of the building elements. By combining these two effects with the technical design of buildings made of steel and/or timber, the concept of sustainable development can be achieved in the long run.Social implicationsThe study concerns sustainability of building structures, which is an important of the sustainable development of the society.Originality/valueThe paper contains new information and will be useful to researchers and civil engineers.

Forces in Bracing Elements of Timber Trusses

This research analyzes the forces in bracing members of timber trusses through numerical modeling using the computational system Strap, considering the three-dimensional structure behavior. The values obtained are compared to values set by the Brazilian standard ABNT NBR 7190 (1997), which considers the side instability of the bracing elements. The results were also compared with the values proposed by the methods of the European standard EUROCODE 5, the South African Standard SABS 0163 (1994) and with the work developed by Underwood (2000). The computer models represent industrial sheds with 12 to 24 meters spam, 24 to 96 meters long with heights of pillars 3, 4 and 6 meters. The structural models analyzed were the Pratt and Howe truss types, considering wood provide from C30 and C40 strength classes. The results show that the forces acting on the bracing of the three-dimensional models are higher than the values obtained by the method of ABNT NBR 7190 (1997), and the values obtained by the methods proposed by EUROCODE 5 and Underwood (2000) are more reliable in the overall behavior of the structure.

The computational analysis of the crack width of beams reinforced with CFRP and steel bars

The aim of the paper is to explain the particular problems related to the use of FRP reinforcement in bending beams. The paper compares the aspect of Serviceability Limit State (SLS) of simply supported concrete beams reinforced with Carbon Fiber Reinforced Polymer (CFRP) bars and three various types of steel bars (the steel grades are 35G2Y, 20G2VY-b and B500SP). The computational analysis of change in crack width under the influence of various level of service live load was investigated. The calculations of beam reinforced with FRP bars was based on Italian design guideline (CNR-DT 203/2006) and the conventional reinforced concrete beams (RC) were analysed in accordance with the European standard Eurocode 2 (EN 1992-1-1:2004).

Using re‐calibrated design S‐N curves for fatigue assessment of road bridges

AbstractFatigue design of road bridges according to Eurocode standards can be based on damage accumulation, provided that information about loading spectrum is available. Characteristic values of fatigue resistance and load effects as well as partial safety factors are introduced in the design equation in order to achieve a target reliability level. Partial safety factors are used to obtain the fatigue design S‐N curves from the characteristic S‐N curves. New probabilistic framework proposed by authors for calibration of fatigue partial safety factors allows for re‐definition of Eurocode‐based design S‐N curves. The new framework improves the confidence in the reliability level represented by the design S‐N curves. In this paper a real case study showing the impact of re‐calibration of design S‐N curves on fatigue design of a road bridge is presented. Importance of choice of design S‐N curves is assessed both in terms of allowable traffic volume and of bridge fatigue design life.

Review of climatic input data for wind load design in accordance with SANS 10160-3

With the publication of Part 3 Wind Actions of the South African Loading Code SANS 10160:2010, several issues concerning adjustments from the reference standard Eurocode EN 1991-1-4:2004 could not be resolved due to lack of sufficient updated background information on South African conditions. The need for updating the map for the free field wind speed is related also to the improved representation of the mixed and complex strong wind climate of the country. Furthermore, strong wind probability models are used for the reliability assessment and calibration of wind design procedures. Updating of the reliability provisions for the revised wind loading process was a further need identified at the time. This paper provides a review of the historical development of the representation of the free field wind, used as input to design wind loading procedures for South Africa. The review considers: (i) the historical representations of the geographic distribution of free field wind, (ii) the climatic influences considered, and (iii) the probabilistic bases for the stipulated wind speed for the reliability provisions for design wind loads. On this basis, the background and motivation are provided for updating SANS 10160-3:2010.

COMPARISON OF METHODS USED FOR SEISMIC ANALYSIS OF STRUCTURES

This paper investigates effects of the seismic load to a structure. The article describes main methods of the definition and practical application of the seismic load based on the Standard Eurocode 8. There was made a comparison of all methods using the same structure. A simple two-storeyed concrete 2D-frame with fixed joints was chosen. A one another model with rigid beams for some calculations was defined. The second model can be used for hand-calculations as a cantilever with two masses. The paper describes main dynamic properties of the chosen structure. Seismic load was defined by lateral force method, modal response spectrum, non-linear time-history analysis and pushover analysis. The time-history analysis is represented by accelerograms. There were made linear and non-linear calculations.

New framework for calibration of partial safety factors for fatigue design

In Eurocode standards, three verification schemes are proposed for fatigue design under variable amplitude loadings: 1) Based on constant amplitude fatigue limit; 2) Based on constant amplitude equivalent stress range at 2 ⋅ 106 cycles; 3) Based on accumulated damage. Characteristic values of fatigue resistance and load effects as well as partial safety factors are introduced in design equations in order to achieve a target reliability level. In this paper a new framework for calibration of fatigue partial safety factors is presented. Three different fatigue limit state functions are formulated for direct comparison with the three verification schemes proposed in Eurocodes. The variable amplitude S-N curves used in this framework are defined using an original probabilistic approach. The presented framework is then applied to two typical bridge fatigue sensitive welded joints. The comparison of results with partial safety factors values recommended in Eurocodes shows that the Eurocode-based partial safety factors should be revised by considering different fatigue sensitive details and by further differentiating between the three verification schemes.

04.20: Bending of rectangular plates subject to non‐uniform pressure distributions relevant to containment structures

ABSTRACTRectangular planform silos are often used where there is need for simple construction or space restrictions. The flexibility of the flat plate walls leads to a horizontal variation in wall pressure across each wall, with much reduced pressures at the mid‐side. There is a clear and systematic relationship between the wall flexural stiffness relative to the stiffness of the stored solid and the pressure pattern on the wall which is now well proven. Since the centre of each wall is subject to significantly reduced pressures, it may be expected that the bending moments in the wall will much lower, permitting the use of a thinner wall. In turn, the thinner wall is then more flexible and leads to a further redistribution of the pressures. This paper is the first to examine the structural consequences of these pressure changes.The horizontal variation of the wall pressure is well captured by a hyperbolic form, with much reduced mid‐side pressures and raised corner pressures, characterised by a single parameter “alpha” that determines the strength of this redistribution. This parameter α is naturally dependent on the relative wall and solid stiffness. In this study, the value of α is varied between the uniform pressure condition α = 0 and a high value (α=3). The highest values occur when a stiff solid is stored in a silo with very flexible walls. Wall plates of different aspect ratio are investigated representing conditions in a square or rectangular silo.The finite element predictions show that great savings can be made in the design of these structures by exploiting the reduced deflections and reduced stresses that arise when realistic patterns of pressure are adopted. The results presented here are suitable for transformation into design rules for the Eurocode standards EN 1993‐1‐7 [1] and EN 1993‐4‐1 [2].

Timber steel-fibre-reinforced concrete floor slabs subjected to fire

This paper presents a finite element model (FE model) for a numerical analysis of a composite steel-fibre-reinforced concrete (SFRC) slab with unprotected secondary timber beams subjected to fire, taking tensile membrane action into account. The material models were calibrated by material tests and push-out tests in a preliminary study, and then the FE model was validated against the results of a full-scale furnace test. The validated FE model takes into account geometric and material nonlinearity, mechanical damage due to thermal loading, and the nonlinear connection between the SFRC slab and the timber beams. A new material model was created to improve the simulated behaviour of the SFRC, especially in tension. The validated FE model was supplemented by a semi-probabilistic safety concept based on the Eurocode standards, and was applied to define the fire resistance of different variants of timber SFRC flooring subjected to fire with various slab dimensions and design loads. This approach will be used to create a catalogue in which the fire resistance will be defined for specific parameters of the structure, for example dimensions, loads and materials. The research presented in this paper follows up on a previous study, which was presented in 2014.

Shear Assessment of Concrete Bridge Deck Slabs

The transitions from old STN standards to Eurocode standards brought several problems into bridge design and assessment. Shear reinforcement is now often required even in concrete members, which were previously allowed to be built without it. Moreover, assessment of existing reinforced concrete bridge structures often shows their insufficiency in shear capacity, which means that they should be strengthened or replaced. Work on new generation of Eurocodes is currently in progress and current model for shear assessment should be replaced by a new (and more precise) one. This paper deals with the problem of shear assessment of concrete bridge according to current standard and also according to the new shear models that are under consideration.