Publications
159 results found
Vollum RL, Fang L, 2012, Shear enhancement in short-span beams with multiple point loads, fib Symposium 2013
Ferrera MP, Melo G, Vollum RL, 2012, Influence of column size and studs arrangement in the punching strength of RC flat slabs, fib Symposium 2013
Bukhari IA, Vollum RL, Ahmad S, et al., 2012, Shear strengthening of short span reinforced concrete beams with CFRP sheets, The Arabian Journal for Science and Engineering B
This paper presents the results of a series of tests on short span reinforced concrete beamswhich were strengthened in shear with various arrangements of externally bonded Carbon FibreReinforced Polymer (CFRP) sheets. The objective of the tests was to determine the effect of changingthe area and location of the CFRP sheet within the shear span. A total of fifteen 150 mm x 300 mm x1,675 mm concrete beams were tested of which four were un-strengthened control specimens. Theremaining eleven beams were strengthened with varying configurations of CFRP sheets. Parametersvaried in the tests included the area of CFRP sheet, its anchorage length and the distance of the CFRPsheet from the support. The experimental results revealed that the CFRP is more effective when it isplaced close to the supports and even small areas of CFRP can give significant increases in shearstrength. The experimental results were compared with the three different existing shear predictionmodels for estimating shear contribution of CFRP sheets. A simple strut-and-tie model (STM) ispresented which gives reasonable predictions of shear strength for the beam specimens, which werestrengthened with CFRP over the full depth of the beam. The superposition method of design isreplaced in EC2 by the variable angle truss model in which all the shear is assumed to be resisted bythe truss mechanism. A simple regression equation is proposed for the calculation of effective stress inFRP to be used in EC2.
Vollum RL, 2012, Influence of Construction loading on long-term slab deflections, Andy Scanlon Symposium on Serviceability and Safety of Concrete Structures: From Research to Practice, Editors: Bischoff, Musselman, Publisher: American Concrete Institute, ISBN: 978-0-87031-757-6
Eder MA, Vollum RL, Elghazouli AY, 2012, Performance of ductile RC flat slab to steel column connections under cyclic loading, ENGINEERING STRUCTURES, Vol: 36, Pages: 239-257, ISSN: 0141-0296
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- Citations: 12
Abela JM, Vollum RL, Izzuddin BA, et al., 2012, Blinding Struts under Long-Term Loading, Magazine of Concrete Research
The term ‘blinding’ is used to describe the thin layer of unreinforced over-site concrete which is used to protect the base of excavations during construction. Blinding is not generally considered as a structural element even though it clearly provides some temporary lateral support to the retaining walls of excavations. The authors have previously shown that that enhanced blinding can be used to prop retaining walls in cut-and-cover excavations during construction prior to the completion of the base slab. This paper describes a series of laboratory tests which the authors carried out to investigate the effect of concrete creep on the axial resistance of blinding struts. The tests show that blinding can creep to failure if the sustained load exceeds a critical value which depends on the imperfection amplitude and profile as well as the strut thickness. The test results are used to validate a numerical model which is subsequently used to carry out a series of parametric studies on full-scale blinding struts.
Vollum RL, 2012, Editorial: Research into Structural Concrete, Magazine of Concrete Research, Vol: 64, Pages: 749-750
Vollum RL, Izzuddin BA, Abela JM, et al., 2011, Blinding Struts – Part 2: Towards A Simplified Design Method, Engineering Structures, Pages: 2573-2583, ISSN: 0141-0296
The companion paper described how concrete blinding can be used to prop retaining walls in cut and cover excavations prior to the completion of the base slab. In addition, it was demonstrated that the behaviour of blinding struts can be accurately predicted with nonlinear finite element analysis (NLFEA) ifthe strut properties and ground profile are known. This paper presents a simple design-oriented analytical model which can be used for blinding struts as an alternative to NLFEA. The simplified model is shown to give comparable results to NLFEA and is attractive for design since it allows the effect of variationsin imperfection amplitude and length to be rapidly assessed. A case study is presented which illustrates the use of the method and demonstrates that relatively thin blinding struts can resist the maximum axial forces likely to be encountered in cut and cover excavations.
Abela JM, Vollum RL, Izzuddin BA, et al., 2011, Blinding Struts – Part 1: Buckling Response, Engineering Structures, Pages: 2563-2572, ISSN: 0141-0296
The term ‘blinding’ is used to describe the thin layer of unreinforced over-site concrete which is used to protect the base of excavations from construction traffic and to provide a clean surface for the construction of the base slab. Blinding is not generally seen or exploited as a structural element even though it clearlyprovides some temporary lateral support to the retaining walls of cut-and-cover excavations. This paper shows that enhanced blinding can be used to prop retaining walls in cut-and-cover excavations during construction prior to the completion of the base slab. An experimental program is conducted on 1/4 scale specimens, which demonstrates that the failure load of blinding struts is governed by upheaval buckling,and which is employed for the validation of nonlinear finite element models. The main parameters governing the buckling load are shown to include: i) the amplitude of the geometrical imperfection, ii)the thickness of blinding, and iii) the eccentricity of the applied load with respect to the centroid of the strut.
Eder MA, Vollum RL, Elghazouli AY, 2011, Inelastic behaviour of tubular column-to-flat slab connections, Journal of Constructional Steel Research, Vol: 67, Pages: 1164-1173, ISSN: 0143-974X
This paper is concerned with the behaviour of ductile shearheads for connecting reinforced concrete flat slabs to internal tubular steel columns. A novel detail is presented in which a gap is left around the column to enable the shearhead to yield in shear prior to the slab failing in punching shear. The proposed connection could serve as a primary lateral resisting system in low-rise buildings in regionsof low to moderate seismicity or as a secondary system in areas of significant seismicity. Test results and numerical analyses are presented for a fully embedded ACI-type shearhead as well as the proposed partially embedded connection. The latter is shown to offer enhanced ductility compared with traditional forms. Experimental and num erical results are used to demonstrate the favourable inelastic performance of the proposed detail.
Hossain TR, Vollum RL, Ahmed SU, 2011, Deflection estimation of reinforced concrete flat plates using ACI method, ACI Structural Journal, Vol: 108, Pages: 405-413, ISSN: 0889-3241
Building codes provide minimum thickness guidelines for two-way slabs to ensure that deflections are not excessive. Thinner slabs areallowed if calculated deflections are found to be acceptable, but there are relatively few reliable deflection measurements in buildings that can be used to assess the accuracy of deflection prediction methods. The construction of the seven-story in-place reinforced concrete frame building in the Building ResearchEstablishment Large Building Test Facility in Cardington, UK, presented a unique opportunity to assess deflection prediction methods for flat plates because deflections, material properties,and loadings were measured. The first two authors have previously shown that long-term deflections were governed by short-term construction loading at Cardington. This paper proposes a refinement to the ACI 318 deflection multiplier approach, which accounts for the effect of short-term construction loading ondeflections. The method is validated with deflection data from Cardington and six slabs tested by the second author.
Sagaseta J, Vollum RL, 2011, Influence of aggregate fracture on shear transfer through cracks in reinforced concrete, MAGAZINE OF CONCRETE RESEARCH, Vol: 63, Pages: 119-137, ISSN: 0024-9831
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- Citations: 46
Sagaseta J, Vollum RL, 2011, Influence of beam cross-section, loading arrangement and aggregate type on shear strength, Magazine of Concrete Research, Vol: 63, Pages: 139-155, ISSN: 0024-9831
Eder MA, Vollum RL, 2010, Seismic performance of hybrid steel column-to flat slab connections, 14th European Conference on Earthquake Engineering
Bukhari IA, Vollum RL, Ahmad S, et al., 2010, Shear strengthening of reinforced concrete beams with CFRP, MAGAZINE OF CONCRETE RESEARCH, Vol: 62, Pages: 65-77, ISSN: 0024-9831
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- Citations: 65
Vollum RL, Abdel-Fattah T, Eder M, et al., 2010, Design of ACI-type punching shear reinforcement to Eurocode 2, MAGAZINE OF CONCRETE RESEARCH, Vol: 62, Pages: 3-16, ISSN: 0024-9831
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- Citations: 15
Eder MA, Vollum RL, Elghazouli AY, 2010, Modelling and experimental assessment of punching shear in flat slabs with shearheads, Engineering Structures, Vol: 32, Pages: 3911-3924, ISSN: 0141-0296
This paper deals with the modelling of punching shear failure in reinforced concrete slabs usingnonlinear finite element analysis. An analytical procedure is presented for simulating punching failure. The procedure is validated for a large-scale reinforced concrete flat slab without shear reinforcement that failed in punching. A parametric analysis is carried out to determine the influence of the key parameters which govern the performance. The analytical procedure is then used to model the response of a large-scale hybrid reinforced concrete flat slab specimen tested at Imperial College London whichfailed in punching. The specimen incorporated a tubular steel column and an ACI 318 type structural steel shearhead. The results of the analysis are used to gain fundamental insights into the contribution of the shearhead to the shear resistance, and to assess the reliability of existing design recommendations for structural steel shearheads.
Eder MA, Vollum RL, Elghazouli AY, 2010, Behaviour and modelling of tubular steel column-to-flat slab assemblages, 4th International Conference on Steel & Composite Structures
Sagaseta J, Vollum RL, 2010, Shear design of short-span beams, Magazine of Concrete Research, Vol: 62, Pages: 267-282, ISSN: 0024-9831
Eurocode 2 presents two alternative methods for accounting for arching action in beams. The simplest option is to reduce the component of shear force owing to loads applied within 2d of the support by the multiple av/2d (whereav is the clear shear span and d is the effective depth). Eurocode 2 also allows short-span beams to be designed with the strut-and-tie method (STM), raising the question of which method to use. This paper presents a simplestrut-and-tie model for short-span beams. The stress fields used in the STM are shown to be broadly consistent with those calculated with non-linear finite-element analysis. The STM is shown to give good predictions of shearstrength, particularly when the concrete strength is calculated in accordance with the recommendations of Collins and Mitchell. The accuracy of the simplified design method in Eurocode 2 is shown to be highly dependent on thestirrup index. The paper also presents data from eight beams tested by the authors which show that aggregate fracture has little if any influence on the shear strength of short-span beams.
Sagaseta J, Vollum RL, 2009, NON-LINEAR FINITE ELEMENT ANALYSIS OF SHEAR CRITICAL HIGH STRENGTH CONCRETE BEAMS, ACEE, Vol: 2, Pages: 95-106, ISSN: 1899-0142
Vollum RL, 2009, Comparison of deflection calculations and span-to-depth ratios in BS8110 and Eurocode 2, Magazine of Concrete Research, Vol: 61, Pages: 465-476, ISSN: 0024-9831
Sagaseta J, Vollum RL, 2009, Relative crack displacements in high strength concrete beams failing in shear, London, The 11th Annual International fib Symposium Concrete 21st Century Superhero, Publisher: emap networks
Abela J, Vollum RL, Izzuddin BA, et al., 2009, Blinding struts in upheaval buckling, London, The 11th Annual International fib Symposium Concrete 21st Century Superhero, Publisher: emap networks
Abela JM, Vollum RL, Izzuddin BA, et al., 2009, Blinding struts in upheaval buckling, 11th Annual International fib Symposium, Concrete: 21st Century Superhero, Publisher: Emaps Network
Amini H, 2009, Nonlinear optimized design of RC members, Concrete Communication Symposium Leeds
Vollum RL, Afshar N, 2009, Influence of Construction loading on deflections in reinforced concrete slabs, Magazine of Concrete Research, Vol: 61, Pages: 3-14, ISSN: 0024-9831
Vollum R, Parker D, 2008, External beam-column joints: design to Eurocode 2, MAGAZINE OF CONCRETE RESEARCH, Vol: 60, Pages: 511-521, ISSN: 0024-9831
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- Citations: 10
Abela JM, Vollum RL, Izzuddin BI, 2008, Upheaval buckling behaviour of blinding struts, The Structural Engineer, Vol: 86, ISSN: 1466-5123
Sagaseta J, Vollum R, 2008, Non-linear finite element analysis of shear critical high-strength concrete beams, AMCM 2008 Analytical models and new concepts in concrete and masonry structures, 6th International Conference Poland
Vollum RL, Afshar N, Izzuddin BA, 2008, Modelling short-term tension stiffening in tension members, Magazine of Concrete Research, Vol: 60, Pages: 291-300, ISSN: 0024-9831
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