bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexural strength enhancement of confined reinforced concrete columns
Authors: Pam H. J. , Ho J. C. M.
Published: November 2009

As part of a continuing research study, this paper proposes a new design aid to calculate the actual moment capacity of confined reinforced concrete columns. Up to now the moment capacity of a reinforced concrete column is calculated based on the code's guidelines for an unconfined section. As most reinforced concrete columns contain transverse or confining reinforcement, which will enhance the column moment capacity, the actual moment capacity will be much higher than the unconfined moment capacity. This additional flexural strength will increase the shear force demand in the column, and if it is not accounted for in the design will jeopardise the column to fail in shear. In this study the actual moment capacity of a confined reinforced concrete column is obtained by multiplying the moment capacity calculated using the BS 8110 method with the proposed flexural strength enhancement factor. By using regression analysis, an equation for the flexural strength enhancement factor is derived as the function of all the parameters that have effects on the moment capacity. An example is presented to show the accuracy of the proposed method.
Holistic design: key to sustainability in concrete construction
Authors: Swamy R. N.
Published: November 2009

There have been unparalleled advances during the latter half of the last century, to the scientific, engineering and social face of the world, but in that process, the world has also been plunged into several interrelated crises. In the context of the construction industry, these crises can be broadly classified in terms of environment, durability and sustainability. The crises have risen from a number of factors such as technological industrialisation, population growth, worldwide urbanisation, and uncontrolled pollution and creation of waste. There is now the real danger that the massive, indiscriminate and wasteful consumption of the world's material and energy resources may result in extensive global warming that is hard to reverse. The price for this environmental abuse is the rapid deterioration and destruction of the world's infrastructure, water shortages, environmental disasters, and material/structural deterioration by the forces of nature. Every crisis experienced in the world has a direct impact on the construction industry, and since the construction industry is closely interlinked with energy, resources and environment, irredeemable environmental degradation can only be prevented by sustainable development of the industry which alone can give hope for a better world and better quality of life. This paper advocates a holistic approach to design and construction integrating all aspects from conceptual design to completion and maintenance during service life.
Flexural strength and ductility of reinforced normal- and high-strength concrete beams
Authors: Pam H. J. , Kwan A. K. H. , Islam M. S.
Published: November 2009

A number of singly reinforced concrete beams made of normal- and high-strength concretes were tested under monotonically increasing loads to study their flexural behaviour and to compare the flexural ductility of normal- and high-strength concrete beams. The flexural strength results verified that British Standard BS 8110, after modification as per the recommendation of The Concrete Society Technical Report 49, is reasonably accurate for application to high-strength concrete beams. On the other hand, the flexural ductility results revealed that the major structural parameters determining the ductility of singly reinforced beams are: (1) for given materials, the tension steel ratio; and (2) in more general cases, the tension steel to balanced steel ratio and the concrete grade. Based on the available test results, a simple formula for predicting the ductility of normal- and high-strength concrete beams is developed. Lastly, in order to avoid brittle failure, it is proposed to set a maximum limit to the tension steel to balanced steel ratio, whose values at different concrete strengths are given in the paper.
The effect of traffic vibration on adhesive curing during installation of bonded external reinforcement
Authors: Barnes R. A. , Mays G. C.
Published: November 2009

This paper describes a programme of research which was conducted to examine the effect of traffic vibration on adhesive curing during the installation of bonded external reinforcement. Steel and carbon fibre reinforced plastic (CFRP) plates were used in conjunction with four epoxy adhesives. A literature review was undertaken in order to select appropriate magnitudes for the strains and frequency of vibration to be used during an experimental programme involving the vibration during cure of lap joints, steel and reinforced concrete beams. The lap joint results show that vibration during cure causes a progressive reduction in strength with increasing strain level. The tests involving strengthened steel beam specimens suggest that use of simple lap joints will give a safe prediction of the effect of vibration during cure. In the reinforced concrete beams there were noticeable differences in failure mechanism between those strengthened with steel as opposed to CFRP plates. However, in both cases failure modes in the concrete masked any effect arising from vibration during cure. Recommendations for the design of externally reinforced concrete elements have been proposed which involve increasing the partial safety factor on the ultimate shear strength of the bonded joint if the joint is to be subject to traffic vibration during cure.
Assessment loading criteria for bridge decks, piers and parapets
Authors: Das P. C.
Published: November 2009

The volume of road traffic in Great Britain has grown rapidly since the 1950s. This has been accompanied by considerable increases in gross vehicle weights. In response to these developments, the traffic loading requirements for bridge design were significantly upgraded in the 1980s. Notwithstanding these enhancements, the network still contains a large number of existing decks, parapets and piers designed to the earlier requirements, a proportion of which may now be at some risk. The authorities are aware that these elements need to be identified and upgraded as soon as possible. Wholesale upgrading of all structures or structural elements to their full design requirements, and maintaining them at that level, is not a practical proposition. Nor is this justifiable as the conditions on some routes represent negligible risk to even the ‘sub-design standard’ structures. Assessment specific criteria for bridge decks which are less onerous than the design requirements have therefore been used formally from the 1960s in order to identify the existing structures in need of upgrading. This paper attempts to derive similar assessment criteria for bridge piers and parapets in respect of accidental vehicle impact. The first part of the paper examines four possible methods that can be used for the purpose deterministic, risk based cost-benefit, target reliability and whole life cost optimisation methods. These methods are somewhat related to each other, in the sense that they all consider the probability of failure in some way. It is concluded that the deterministic criteria, which can be justified as being based on simple engineering judgement, produce in reality similar results to the other approaches. In the second part of the paper, the assessment criteria for existing piers and parapets are therefore derived using a deterministic approach based on the maximum speeds of vehicles on specific types of road.
When should shear-flexible stability functions be used in elastic structural analysis?
Authors: Mottram J. T. , Aberle M.
Published: November 2009

Linear, non-linear and stability analyses of elastic structures with shear-flexible beam-columns require knowledge of shear-flexible stability functions. Carry-over and stiffness functions are to be found in the literature. New functions are derived so that compatibility of slope is ensured at the joints. Previous work has not focused on the practical issue of when these displacement functions should be used. Here it is shown that shear-flexibility should be included in linear matrix structural analysis format when the shear-flexibility parameter of members is >0·025.
Vortex-induced vibrations of the Second Severn Crossing cable-stayed bridge—full-scale and wind tunnel measurements
Authors: Macdonald J. H. G. , Irwin P. A. , Fletcher M. S.
Published: November 2009

In the first winter after opening, the Second Severn Crossing cable-stayed bridge exhibited occasional vortex-induced vertical oscillations. Vortex excitation had been detected by the wind tunnel tests on sectional models during design and an aerodynamic solution partly developed but, based on damping and turbulence assumptions from recognised design codes, it had been concluded that the probability of large vibrations occurring was small. Full-scale monitoring of both wind and structural response enabled the causes of the observed oscillations to be investigated. The structural damping and wind turbulence were found to differ significantly from the assumed values. Additional wind tunnel tests were undertaken using the full-scale measured values with a view to replicating the full-scale behaviour and developing a solution. Taking into consideration the revised damping and turbulence and an often-ignored factor to correct for the full-scale mode shape, good agreement between the model and full-scale measurements was obtained. Also, aerodynamic solutions were further explored, as a result of which baffle plates were installed under the bridge. Since their installation, no further signs of vortex-induced oscillations have been observed.
Comparison of seismic design methods for irregular RC bridges
Authors: Georgakis C. T. , MacKenzie D. K.
Published: November 2009

In this paper, the non-linear seismic response of an irregular 457 m reinforced concrete (RC) box girder bridge is examined in detail. The bridge was originally designed based on the current prevailing international design capacity philosophy, in which bridge strength and ductility capacities are designed to meet strength and ductility demands—as found from a response spectrum analysis. To determine the appropriateness of this design approach, a non-linear time-history analysis methodology is devised for the bridge. As part of this methodology, synthetic accelerograms are created, based on a site-specific response spectrum, and used in non-linear time-history analyses of the bridge, in which ductile elements have been modelled using bilinear hysteresis models. The results obtained from the linear and non-linear analyses are compared and significant deviations in load effects and ductility demands are found at key locations along the bridge. The significance of these deviations is discussed. Additionally, seismic performance enhancing bridge design alterations are also suggested.
Adaptive control of structures by LMS algorithm: a comparative study
Authors: Golafshani A. A. , Mirdamadi H. R.
Published: November 2009

By using the normalised least mean squared (NLMS) algorithm, a semi-active multi-variable adaptive controller is designed for a seismically excited structure. There is no need for a large power supply. A number of valves and battery size low-power supplies will suffice. The valves control the amount of flow of a fluid through bypass on-off orifice channels in installed energy dissipating mechanisms. Each mechanism is composed of a piston attached to a Λ-shaped chevron wind-bracing on each floor and to a cylinder attached to the upper floor. Adaptive controller parameters are estimated by the LMS optimiser, in order to search for optimal non-classical damping coefficients of the dissipating systems. They are equivalent to changing the orifice size of the bypass channels. Two versions of the LMS algorithm are used for comparative purposes: the filtered-x LMS and the classical (non-filtered) LMS. For the filtered-x version; two cases are distinguished for a more refined comparison: first, required structural transfer functions for estimating filtered-x signals are assumed to be exact and, second, these transfer functions are assumed not to be exact. Simulation results show that structural responses obtained by filtered-x LMS are more optimised than that of classical LMS, even in the case when the estimation of filtered-x signals is assumed to be poor.
Holistic behaviour of concrete buildings in fire
Authors: Bailey C.
Published: November 2009

This paper discusses various modes of structural behaviour of a concrete building when subjected to a fire, based on observations from a full-scale test. Although some data were lost during the test, the available results and observations presented provide a valuable insight into the holistic behaviour of concrete buildings when subjected to fire. The tested building was constructed using elements formed from normal and high-strength concrete and was designed for 60 min fire resistance, using the UK Design Code. High-strength concrete was used for the columns within the fire compartment and since it has previously been shown that this type of concrete is susceptible to spalling, polypropylene fibres were added to the concrete mix during construction to alleviate the problem. Both the UK and European codified design methods suggest that concrete spalling within the fire compartment should have been nominal and could effectively be ignored during the design. However the test showed that spalling of the floor slab was extensive and exposed the bottom steel reinforcement. Although concrete spalling considerably reduced the flexural strength of the slab, collapse did not occur. This could be attributed to the slab behaving in compressive membrane action, which is currently not considered in codified design methods. The test also showed significant lateral displacement of external columns due to thermal expansion of the heated slab. The main observations from the test show that designers will need to understand the behaviour of entire structures in fire, to ensure that premature collapse will not occur.
Global stability analysis and structural performance of buildings braced by infilled frames
Authors: Zalka K. A.
Published: November 2009

A closed-form solution is given for the in-plane buckling analysis of infilled frames. The dominant stiffness characteristics are established as the shear stiffness (associated with the beams and the masonry infill) and the bending stiffness (whose value can be most effectively estimated by the global second moments of area of the columns). Guidelines are given to maximise the critical load of infilled frames. A simple procedure is presented for the three-dimensional global stability analysis of buildings braced by infilled frames. The value of the global critical load depends on the basic (sway and torsional) critical loads and their interaction. Particular attention is paid to torsional behaviour. The most effective ways to improve torsional behaviour are shown, leading to optimum structural performance. The global critical load ratio is introduced as a performance indicator. It is demonstrated that there is a direct link among stability, dynamic behaviour and global deformations. When a bracing system is properly designed for stability, then the building, under horizontal loads, normally develops rotations and translations of acceptable magnitude and its fundamental frequency tends to be sufficiently great. Three worked examples show the easy use of the methods and the application of the global critical load ratio to monitoring structural performance.
Prediction of slab deflections and validation against Cardington data
Authors: Hossain T. R. , Vollum R. L.
Published: November 2009

This paper presents a novel incremental procedure for the prediction of slab deflection due to a time-varying load. The procedure extends the moment curvature method given in CEB-FIP Model Code for Concrete Structures 1990 (MC90). The procedure has been incorporated into a finite-element program which has been used to predict long-term slab deflections in the Cardington in-situ concrete building. It is shown that long-term deflections in the Cardington slabs are underestimated significantly if the effect of construction loading is neglected. A simplified method is proposed for calculating deflection which takes construction loading into account.
A truss analogy and neural network for reinforced concrete deep beam analysis
Authors: Jenkins W. M.
Published: November 2009

Two simple neural networks are used to produce a generalised analysis of deep reinforced concrete beams based on a pin-jointed truss analogy. The first network carries out the structural analyses needed in the preparation of the training data required for the second neural net which then provides rapid analyses of beams described by four design parameters. When preparing the training data an iterative method is used to identify and remove concrete members cracked in tension. The output from the trained neural net consists of applied shear levels at first flexural and diagonal concrete cracking and at ultimate conditions.
Design of bridge decks utilising arching effects
Authors: Collings D.
Published: November 2009

This paper outlines a relatively simple method for designing reinforced concrete slabs utilising in-plane membrane action. The method utilises and modifies existing analysis techniques commonly used in design offices for the design of bridge decks. The method indicates that lower reinforcement requirements can be justified for some constrained slab panels. Two examples are provided to demonstrate the method and compare results with conventional methods.
Cyclic behaviour of deep reinforced concrete coupling beams
Authors: Kwan A. K. H. , Zhao Z.-Z.
Published: November 2009

Six half-scale models of reinforced concrete coupling beams with span/depth ratios ≤ 2·0 were tested under reversed cyclic load by a newly developed test method that can accurately simulate the boundary conditions of coupling beams in coupled shear wall structures. Five of them were conventionally reinforced and one was diagonally reinforced. Span/depth ratio and reinforcement layout were the main structural variables studied. Test results revealed that the deep conventionally reinforced coupling beams behaved quite differently from the ordinary beams in frame structures. Generally, shear failure was more likely to occur. Moreover, the additional longitudinal reinforcement bars (those placed near the centroidal axis) could contribute significantly to bending strength and therefore lead to an increase in shear demand. Nevertheless, the measured drift ratios of the conventionally reinforced coupling beams still reached 3·6–5·7%, which are not small for deep coupling beams. On the other hand, it was found that the provision of diagonal reinforcement radically changed the load resisting mechanism and significantly improved the energy dissipation capacity of the coupling beam. However, it had not improved the deformability of the coupling beam.
Passive pressure development in masonry arch bridges
Authors: Burroughs P. , Hughes T. G. , Hee S. , Davies M. C. R.
Published: November 2009

This paper considers the development of lateral passive pressures during the failure of masonry arch bridges. It has been known for some time that the sway failure mechanism of these bridges develops significant stabilising soil pressures but quantitative figures for use in bridge assessment remain largely unknown, particularly for deep arches. This paper considers the pressures developed for two geometries typical of the range of structures found in the UK, one of span/rise = 4 and the other semicircular. The experiments were performed in a geotechnical centrifuge using 1/12th scale models of a 6 m, single-span, three-ring, brickwork arch. The results confirm earlier work suggesting that full passive pressure limits are not reached; however, it is clear that for the soil type tested limiting soil pressures at all monitored locations were achieved. A passive pressure profile is postulated for arch bridge assessment and application of the profile to the assessment of the two bridges tested is undertaken.
Mechanism analysis of single span masonry arch bridges using a spreadsheet
Authors: Hughes T. G. , Hee S. C. , Soms E.
Published: November 2009

This paper contains details of the application of a sophisticated mechanism analysis to single span segmental masonry arch bridges using a standard spreadsheet. The method characterises the failure load directly in relation to the load and hinge positions and then uses the standard optimisation package within the spreadsheet to find their optimum locations. The analysis includes the ability to model yielding at the hinges, the passive resistance of the soil, multi-axles and, to a limited extent, the effect of large deformations. An example application is given and the results are compared to recent experiments.
Ultimate strength of externally strengthened prestressed beams
Authors: Ghallab A. , Beeby A. W.
Published: November 2009

It is sometimes necessary to increase the load capacity of bridges to cope with increased traffic loads. This can be achieved using external prestressing which increases the load capacity of the bridge speedily with little traffic obstruction and without significant added weight. However, this method will be used widely only if its effect on the ultimate moment of resistance of the strengthened beams is understood. Furthermore, for design purposes, a simple method to determine the ultimate moment of the strengthened beams is required. In this paper six factors were studied to investigate their effect on the prestressed beams strengthened using type G Parafil rope. These factors are the value of the external prestressing force, number of deviators, effective depth of the external prestressing force, maximum load prior to strengthening, concrete strength and span/depth ratio. An analytical investigation has also been carried out to develop a simple general equation for the ultimate strength of the beams. The comparison between the experimental and the theoretical results show very good agreement.
Shrinkage properties of normal and high strength fibre reinforced concrete
Authors: Barr B. , El-Baden A.
Published: November 2009

This paper reports on a study of shrinkage–weight loss relationships for normal and high strength plain and fibre reinforced concrete. Three fibre concentrations (1, 2 and 3% by weight) and five concrete grades (in the range 40–120 MPa) were used in the study. Four test specimen sizes were used to investigate the influence of effective thickness, three being cylinders with diameters of 100, 150 and 200 mm and a height/diameter ratio of two and the fourth being 76 × 76 × 254 mm prisms. All specimens were subjected to standard air drying in a temperature and humidity controlled laboratory (RH 65 ± 5% and temperature 20 ± 2°C) for either 100 days or 1 year. The test specimens were unsealed and hence the contribution of autogenous shrinkage was not evaluated separately. In general, the results show that high strength concrete has a similar long-term variation of shrinkage and weight loss with time to that observed for normal strength concrete and the relationship between shrinkage and weight loss during the first 100 days of drying is approximately linear for all grades of concrete. The main influence of fibre reinforcement is to reduce the development of early shrinkage strains and 1% fibre concentration is sufficient for this purpose. The test results have been compared with results obtained from two prediction models and it is concluded that further work is necessary to improve prediction models for application to high strength concrete and in particular to improve the prediction of early shrinkage strains.
Strengthening reinforced concrete beams with external unbonded bars: theoretical investigation
Authors: Cairns J. , Rafeeqi S. F. A.
Published: November 2009

The paper describes the development of a numerical model for analysis of beams retrofitted with external unbonded reinforcement. The experimental phase of the investigation is described in a companion paper, which also outlines the advantages of the method. Because external reinforcement is not bonded to the beam throughout its span, but is anchored only at the ends, normal plane section behaviour assumptions cannot be used. The numerical model is based on section analysis, and incorporates non-linear material behaviour and non-linear geometric effects. The model is first validated against results from an experimental programme comprising 35 physical tests on laboratory specimens. The model is then used to supplement the experimental study by exploring parameters which could not receive adequate experimental coverage. The influence of the shape of the bending moment diagram and of span/depth ratio, parameters which were not adequately explored in the experimental investigation, are reported. Deflectors were typically calculated to double strength enhancement at shorter span/depth ratios; the benefits were greater with higher ratios. Their use will be advantageous in the majority of situations.
Shear strengthening of existing concrete bridges
Authors: Valerio P. , Ibell T. J.
Published: November 2009

The shear capacity of existing concrete bridge beams is often inadequate and unable to meet current code requirements. This is often due to increased traffic loads, inadequate shear-resistance provision in the original design or deterioration of materials due to aggressive environments. This paper deals with a new type of shear strengthening for existing concrete bridges. It is proposed that vertical steel or fibre-reinforced plastic bars be inserted into pre-drilled holes and fastened in place using epoxy resin. This method has the advantage that only the soffit of the concrete bridge beam (or slab) is required for access, allowing the top surface to remain undamaged during strengthening. This could allow the bridge to be used during strengthening works, with traffic relatively unhindered by work being carried out below. Further, no threaded bars and plates are required in this scheme, solving the notorious installation and maintenance problems associated with present shear-strengthening schemes. Ten laboratory tests are presented here to demonstrate the system, and comparisons are made against current code predictions for the strength of such concrete beams with and without transverse reinforcement. An upper-bound plasticity-based solution is also provided as a means to explain enhancement in shear capacity in specimens with very few embedded vertical bars. The results of this work show that the proposed strengthening scheme is effective and provides significant improvement in the shear-carrying load capacity. Additionally, code predictions for capacity of the strengthened beams are rather accurate, so that this strengthening method may be adopted with confidence.
Local and post-local buckling of double skin composite panels
Authors: Liang Q. Q. , Uy B. , Wright H. D. , Bradford M. A.
Published: November 2009

Double skin composite (DSC) panels are constructed by filling concrete between two steel plates welded with stud shear connectors at a regular spacing. Steel plates in DSC panels used as two-way slabs or shearwalls may buckle locally between stud shear connectors when subjected to in-plane biaxial compression. This paper investigates the local and post-local buckling behaviour of biaxially compressed steel plates restrained by shear connectors and concrete in DSC panels by using the finite element modelling technique. Local buckling coefficients are obtained for steel plates with various aspect ratios, biaxial loading and boundary conditions by incorporating the shear stiffness effect of stud shear connectors. These buckling coefficients can be used to determine limiting width-to-thickness ratios for steel plates and the distribution of stud shear connectors. A geometric and material non-linear analysis is undertaken to quantify the post-local buckling strength of steel plates under biaxial compression. The initial imperfections of steel plates and non-linear shear–slip characteristics of stud shear connectors are taken into account in the post-local buckling analysis. Based on numerical results, biaxial strength interaction curves and formulae are developed for the ultimate strength design of steel plates in double skin composite construction.
Energy approach to assessing corrosion damaged structures
Authors: Smith J. W.
Published: November 2009

Unclad steel structures in chemical plant are susceptible to severe damage by corrosion. Their safety is dependent on effective inspection and maintenance. However, corrosion may occur in unexpected or concealed locations. A method for identifying the most critical members is proposed so that they may be inspected more carefully. The method is based on finding the sequence of damaged members that, if destroyed, would cause collapse but would require the least amount of energy to do so. A systematic search procedure is used, similar to shortest route algorithms in traffic engineering. The procedure is incorporated within a conventional finite element program, and therefore a wide range of structural forms may be analysed. It is shown that slender diagonal bracing members are the most vulnerable.
Thermal actions on a steel box girder bridge
Authors: Lucas J.-M. , Berred A. , Louis C.
Published: November 2009

Most studies of thermal actions on bridges have been devoted to concrete structures. In this paper, we focus our analysis on steel box girder bridges. The statistical analysis is based on data collected over a three-year period by temperature gauges placed in appropriate places on the Normandy Bridge, France. Temperature–time series are generally known to contain a deterministic and a random part. The deterministic component is due to the natural seasonal fluctuation over a whole year. The same phenomenon has been observed in the case of the Normandy Bridge. At design stage, engineers need to know the extreme fluctuations of thermal actions (average temperature and thermal gradient) to ensure the durability and safety of a structure. Design codes prescribe extreme values called characteristic values defined on a return period of 50 years. The statistical analysis allows the calculation of these characteristic values as well as frequent and quasi-permanent values.
Physical testing for concentrically loaded columns of pultruded glass fibre reinforced plastic profile
Authors: Mottram J. T. , Brown N. D. , Anderson D.
Published: November 2009

This paper concerns polymeric composite columns manufactured by the pultrusion process. The behaviour of such members is investigated to provide a basis for future assessment of design methods. The minor-axis buckling characteristics of twelve wide-flange columns are presented. The main parameters varied are height (6·3 m, 4·8 m and 3·3 m) and nominal cross-sectional dimensions (152 × 152 × 9·53 mm, 203 × 203 × 9·53 mm and 203 × 203 × 12·7 mm). Deformation and failure characteristics are presented. It is found that theoretical Euler critical buckling loads generally correlate well with maximum test loads and critical loads derived from Southwell plots. A detailed discussion is presented to show that differences are due to imperfections in the column specimens and the test rig. At the shortest column height, the onset of local compression flange buckling is found to lower resistance by way of modal-coupling with the global bending deformation.
A spatial displacement model for skewed multi-rib T-beams
Authors: Wang R. H. , Luo Q. Z. , Tang J. , Li Q. S.
Published: November 2009

A generalised finite segment method for the analysis of a skewed multi-rib T-beam is presented in this paper. Using the skewed beam element under an inclined coordinate system for the skewed deck and normal beam element for the ribs, a spatial displacement field for the composite structure is constructed. Shear lag effect and local flexure of the deck are taken into consideration in constructing the displacement field, as well as the stiffness of the transverse diaphragm. The formulation of the finite segment is established based on the variational principle. The proposed method simplifies a three-dimensional structure into a one-dimensional structure such as a beam for structural analysis and therefore reduces the computational efforts significantly. Numerical examples are given to illustrate the application of the proposed approach. It is shown through the examples that the results obtained using the proposed finite segment approach are in agreement with the experimental data, verifying the accuracy of the proposed method.
Foundation and structural design of the Bibliotheca Alexandrina
Authors: Hamza M. , Ghoneim M.
Published: November 2009

Nearly 2,300 years ago, a great enterprise was conceived in Alexandria, the ancient Bibliotheca Alexandrina. At the beginning of the third millennium the new Bibliotheca Alexandrina has been built alongside the University of Alexandria overlooking the Mediterranean Sea. The Library is planned as a public library. The design concept, the critical ground conditions and the aggressive saline environment, due to the proximity to the sea, required remarkable foundation and structural works. This paper presents the foundation and structural design of the Bibliotheca Alexandrina. The various elements of the library building are described and the structural design challenges are summarised. The sophisticated geotechnical and structural analyses that were carried out during the design stage are also described.
Wind-induced vibration analysis of the Hong Kong Ting Kau Bridge
Authors: Su C. , Han D. J. , Yan Q. S. , Au F. T. K. , Tham L. G. , Lee P. K. K. , Lam K. M. , Wong K. Y.
Published: November 2009

Because of their high flexibility and relatively low structural damping, long-span bridges are prone to wind-induced vibration. An efficient wind field simulation technique for wind-induced vibration analysis of long-span bridges is first introduced in this paper. The time-domain expressions for the buffeting and self-excited forces acting on long-span bridges can then be found from the wind velocities. Based on the above theory and the aerodynamic parameters obtained by wind tunnel tests, a study of the wind fluctuations and aerodynamic forces is carried out on the Hong Kong Ting Kau Bridge, which is a cable-stayed bridge comprising two main spans and two side spans. The buffeting response of the bridge is analysed in the time domain by using step-by-step numerical integration techniques. The aerodynamic behaviour of the bridge can therefore be obtained, and the safety performance of the bridge against strong wind can further be evaluated. Numerical results basically agree with the experimental data, indicating that the theory presented in this paper is applicable to engineering practice.
Construction over nineteenth century brick railway tunnels
Authors: Brown A. J. H.
Published: November 2009

The construction of the new BullRing in Birmingham, is sited on two brickwork railway tunnels, built between 1849 and 1864, both of which are in full use. This paper is concerned with the construction requirements and process above these tunnels, and how these risks were identified, analysed and mitigated.
Façade failure effects on blast propagation along city streets
Authors: Smith P. D. , Rose T. A. , Krahe S. L. , Franks M. A.
Published: November 2009

In assessing the potential hazard to buildings and people in a city landscape, it is usual to assume that building façades are perfectly rigid reflecting surfaces. This is an attractive assumption because it results in conservative estimations of impulse loads at locations remote from the explosion. Similarly, it enables both small-scale physical modelling and numerical simulation to be performed without the need for structural prototypes or response calculations. However, close to the source of an explosion, damage to building façades can be devastating. It is not unusual for all the glazing elements, light cladding and architectural features to be completely removed, leaving only the steel or reinforced concrete skeleton of the building. Because this region of devastation allows blast to enter the building, pressures and impulses experienced at locations further down the street in which the building is located will be reduced. The extent and significance, or otherwise, of any reduction is difficult to quantify as is the intensity of the blast that enters the building by way of the failed façade. The investigation presented in this paper has two complementary components. In the first part it is assumed that light, non-structural elements (such as windows) close to the source of an explosion, break instantly on detonation, and they do not impede the passage of the blast into the affected buildings. This approach allows the blast to propagate both through the buildings nearby, as well as along the street, or streets, in the vicinity of the building. In the second part, a complete building (forming part of a street of buildings) is studied. This building has frangible façade elements, separate floors, side and rear walls and a roof. The blast that enters the building is measured at locations on the central ‘core’ of the building. From the first part of the study, reduction in blast impulse resulting from the ingress into adjacent buildings has been quantified by both small-scale experiments and numerical simulations in which the proportion of façade removed from the buildings (termed ‘building porosity’) was varied systematically. A similar approach is used in the second part, where blast has entered the building, to assess the effects on blast resultants both when the walls of the building remain in place and when they are removed (corresponding to a low level of wall ‘robustness’). For the first part, results are presented in the form of impulse against scaled distance for various degrees of porosity and are compared with the performance of rigid façades. For the second part comparisons of the blast environment are made for different façade configurations and different levels of behind-façade confinement.
Dynamic stiffness of reinforced concrete beams
Authors: Numayr K. S. , Al-Jallamdeh S. A. , Al-Akhras N. M.
Published: November 2009

This study investigates the flexural stiffness rigidity of reinforced concrete beams under dynamic excitation. The dynamic stiffness was determined from the natural frequency of vibration of reinforced concrete beams statically loaded to various levels into the cracked regime. A non-linear moment–curvature model was used in the analysis to account for the concrete nonlinearity arising from the material cracking. The finite-element method was used in the study to solve the nonlinear equations and determine the values of natural frequency and dynamic stiffness. The variation of the natural frequency with increased applied load is studied and compared with that available in the literature. The study showed that the variation of applied load with natural frequency using the non-linear analysis agrees well with that obtained experimentally for small applied loads. The variation of applied load with static deflection using the non-linear analysis coincides well with that obtained experimentally for applied loads up to the cracking load. The natural frequency and static deflection using the effective moment of inertia based on the ACI building code are lower than those obtained using the non-linear analysis for applied loads greater than the cracking load.
Development of self-compacting concrete
Authors: Goodier C. I.
Published: November 2009

Self-compacting concrete (SCC) can be defined as a fresh concrete which possesses superior flowability under maintained stability (i.e. no segregation) thus allowing self-compaction—that is, material consolidation without addition of energy. It was first developed in Japan in 1988 in order to achieve durable concrete structures by improving quality in the construction process. This was also partly in response to the reduction in the numbers of skilled workers available in the industry. This paper outlines a brief history of SCC from its origins in Japan to the development of the material throughout Europe. Research and development into SCC in the UK and Europe are discussed, together with a look at the future for the material in Europe and the rest of the world. Research and development of SCC is being conducted by private companies (mainly product development), by universities (mainly pure research into the material's properties), by national bodies and working groups (mainly the production of national guidelines and specifications) and at European level (Brite-EuRam and RILEM projects on test methods and the casting of SCC, respectively). Although SCC is not expected to ever completely replace conventionally vibrated concrete, the use of the material in both the precast and ready-mix markets in the UK, Europe and the rest of the world is expected to continue to increase as the experience and technology improves, the clients demand a higher-quality finished product and the availability of skilled labour continues to decrease.
A code of practice for the structural design of fibre composites
Authors: Ayers S. R. , Van Erp G. M.
Published: November 2009

The lack of appropriate structural design standards for composite materials is a major inhibitor to the wider usage of these materials in mainstream civil engineering. In 2000, the Composites Institute of Australia (CIA) moved to address this problem on a national level and initiated a programme to develop an Australian industry code of practice for the structural design of fibre composites. This paper discusses two of the initial topics addressed by this programme: the development of a national system of grading and certification for composite constituents, and an alternative approach to the characterisation of unidirectional lamina behaviour. The paper outlines the basis for investigation of each of these topics, and discusses the research approach that has been adopted. In the case of characterisation of lamina behaviour, the paper also presents initial results from associated experimental programmes.
Mechanical splice of grid carbon fibre-reinforced polymer reinforcement and steel plate
Authors: Sekijima K. , Kuhara T. , Seki S. , Konno T.
Published: November 2009

A new shield-cuttable tunnel wall system has been developed. This system enables a shield tunnelling machine to break in or break out by directly cutting the launch or arrival part of the concrete wall of a vertical shaft with its cutter bits without performing prior ground improvement works and manual demolition. When this system is applied to a column-type diaphragm wall, H-shaped steel piles used as the reinforcement in the wall should be replaced by bit-cuttable mixed-in-place mortar piles reinforced with carbon fibre reinforced polymer (CFRP). In order to connect the grid CFRP reinforcement and the flange of H-shaped steel, a specially designed mechanical splice has been developed. Tension tests of the mechanical splices were carried out to investigate their mechanical behaviour. The mechanical splice was applied to the newest subway tunnel in Tokyo.
A novel advanced polymer composite/concrete structural element
Authors: Hulatt J. A. , Hollaway L C. , Thorne A.
Published: November 2009

The paper discusses the use of a new advanced polymer composite material, and a modification of it, formed by pre-impregnating fibres with an epoxy polymer matrix; the composite materials are ideally suited for use in the civil engineering industry. These composite materials have been combined with concrete to form a novel structural system; these dissimilar materials have been utilised to their best structural advantage with concrete wholly in compression and the composite in tension. The illustrative structural systems are T-beams. Two beam types, of identical external geometry, were investigated: one had a free top surface exposed to the environment (beam a), whereas the other (beam b) had confined concrete. Three designs were made and tested to examine: (i) the buckling failure of the composite webs of beam type (a), (ii) the overall failure of a shear bond (a shear failure between the permanent shuttering and the concrete) beam type (a), and (iii) the overall failure of a shear bond beam type (b). The results indicate that the beams under type (i) test failed by buckling of the web followed by crushing of the concrete and buckling of the permanent glass fibre reinforced polymer composite shuttering. The beams under type (ii) test failed by crushing of the concrete and buckling of the permanent shuttering, and the beams under type (iii) test failed by local buckling of the glass fibre reinforced polymer composite cap confining the concrete and a failure that, on investigation, manifested itself as a tensile separation of the concrete within the cap. These type (b) beams have an improved ultimate strength and, overall, a more ductile response compared with the type (a) beams under type (ii) test.
Mechanical/bonded joints for advanced composite structures
Authors: Lees J. M. , Makarov G.
Published: November 2009

The strengths of mechanical-connected and adhesive-bonded joining systems are combined to develop an improved connection system for advanced composite materials. The principle of resistance enhancement is based on the insertion of small diameter pins through an adhesive joint. The pins act as local reinforcement in the most highly stressed regions of the joint, enabling an adhesive joint to carry an increased load prior to failure. In a series of single-lap shear experiments using glass fibre reinforced polymer samples, adhesive-only and pinned-only specimens failed in the joint region. In contrast, many of the pinned/bonded specimens failed away from the joint at a significantly higher load. Insight was gained regarding the influence of the pin material, diameter, number and configuration on the resulting performance. The results demonstrated the potential of pinned/bonded systems as a new method for connecting composite materials. However, further work is necessary to confirm the sensitivity of the results to changes in parameters such as the fibre architecture, adherend geometry, adhesive interface and joint configuration.
In-service performance of glass reinforced plastic composites in buildings
Authors: Halliwell S.
Published: November 2009

Fibre-reinforced polymers (FRPs) have found increasing use in construction applications over the last four decades. One of the key factors in their success is the long-term durability they offer. Structures erected in the late 1960s and early 1970s are still meeting performance requirements, and several examples of these are cited in this paper. Improvements in materials technology mean that the properties of FRP components produced today are at least as good as, if not much improved on, those available 40 years ago. This, along with the need for improved construction processes, suggests an increase in the application of FRP materials in construction in the future. The work reported in this paper forms part of a much larger site investigation project, funded through the UK's Department of Trade and Industry, covering many types of application of composites in construction. The results reported here confirm that modern durable FRP structures can be designed and constructed.