Publications
388 results found
Liapopoulou M, Stafford PJ, Elghazouli AY, 2024, Duration-dependent seismic collapse capacity prediction for steel moment-resisting frames, Journal of Building Engineering, Vol: 86, ISSN: 2352-7102
This paper presents a prediction model for the seismic collapse capacity of multi-storey steel moment-resisting frames with due account of duration effects. The main objective is to provide a simplified and accurate analytical approach for the prediction of the duration-consistent collapse capacity. For this purpose, incremental dynamic analyses are carried out on 96 steel frames designed to Eurocode 8 for various combinations of ground conditions and drift limits. A set of 67 earthquake records with varying 5–75% significant duration is matched by scaling to a target Eurocode 8 response spectrum and employed in the analyses, to avoid spectral shape bias in the results. The influence of duration on the collapse capacity is quantified with due consideration of other ground motion properties and structural characteristics. It is shown that a decrease in the fundamental period or in the P−Δ effect results in more pronounced duration effects. Correlation analyses are also carried out between the logarithmic collapse capacity and the strong motion duration, as well as other ground motion and structural parameters. Based on the results, the most important parameters are identified, and a regression model is developed for predicting the collapse capacity as a function of the fundamental period, second-order level, plasticity resistance ratio, first-mode participation factor, and the 5–75% significant duration. Comparative assessments with other models from the literature highlight the importance of including the strong motion duration as a collapse predictor, since duration-independent models may result in unrealistic predictions. Finally, possible approaches for incorporating the strong motion duration in practical code-based collapse assessment procedures are outlined and discussed.
Liapopoulou M, Stafford PJ, Elghazouli AY, 2024, A collapse capacity prediction model based on ground motion duration, Engineering Structures, Vol: 304, ISSN: 0141-0296
A prediction model for the seismic collapse capacity, which explicitly considers the influence of strong motion duration, in addition to key structural properties, is presented in this study. The model is developed based on incremental dynamic analyses of single-degree-of-freedom systems, employing a set of 67 earthquake records. The selected ground motions are matched by scaling to a target Eurocode 8 response spectrum, to avoid spectral shape bias in the results, and have varying 5–75% significant duration from about 5 s up to nearly 70 s. The structural models exhibit vibration periods in the range of 0.2 s to 3.0 s, varying negative slope in their post-capping branch from 0.02 to 0.30, and ductility between 1.0 and 6.0. Each oscillator is assigned bilinear and pinching hysteresis. Correlation coefficients are computed between the collapse capacity and the structural properties examined, as well as three ground motion parameters, which include the duration, Arias Intensity, and Husid plot slope. The period, post-capping slope, and ductility are all shown to be strongly correlated to collapse resistance while, among the ground motion variables, the duration exhibits the highest correlation. Based on iteratively reweighted least squares, predictive models are fitted to the collapse capacity data, providing estimates for the median collapse capacity and the variance. The predicted collapse capacity associated with the maximum duration considered is found to be up to 67% lower than that corresponding to the minimum duration. The rate of collapse capacity reduction with duration is shown to depend on the period, P-Δ level, hysteresis type, and the duration value itself. The proposed model is compared to those from previous studies and is shown to provide a simple and computationally efficient method to obtain collapse capacity estimates for specific target levels of strong motion duration.
Elzeadani M, Bompa DV, Elghazouli AY, 2024, Data on the axial response of steel tubes infilled with rubberised alkali-activated concrete, Data in Brief, Vol: 53, ISSN: 2352-3409
The presented data cover experimental and numerical axial load-shortening results of steel tubes infilled with rubberised alkali-activated concrete. The experimental data are obtained from 36 concrete filled steel tube specimens with circular and square cross-sections, length-to-diameter/width ratios of 2 and 4, and three different rubber contents in the concrete infill. The data from the numerical assessment cover the axial load-shortening response of over 300 finite element models. These cover a wide range of concrete infill strengths and rubber contents, steel tube grades, specimen widths, and steel tube wall thicknesses. Detailed descriptions of the material and methods, experimental testing, and numerical modelling procedures are also provided. The data reported herein supports the discussion in the research article "Axial compressive behaviour of composite steel elements incorporating rubberised alkali-activated concrete," and in the case of the numerical parametric assessment, give for the first time the full axial load-shortening response of all the models considered.
Mujdeci A, Guo YT, Bompa DV, et al., 2024, Performance of circular steel tubes infilled with rubberised concrete under cyclic loads, Engineering Structures, Vol: 302, ISSN: 0141-0296
This paper presents a detailed numerical investigation into the inelastic cyclic performance of circular steel tubes filled with rubberised concrete materials. The study considers rubberised concrete infills with relatively high values of up to 60% volumetric rubber replacement of conventional mineral aggregates, which is lacking in existing investigations. Co-existing axial loads of up to 30% of the nominal composite cross-section capacity are also considered. Modified continuum finite element modelling procedures are proposed and employed to account for the high cumulative deformations and damage development of rubberised concrete under cyclic loading. In particular, the influence of crack opening and closure in concrete under cyclic loading is examined and discussed. In addition to full numerical cyclic analyses, idealised monotonic simulations are also proposed and verified to enable computationally efficient representation of the envelope response. Validations of the full-cyclic and envelope-monotonic models are carried out against available experimental cyclic results, indicating the suitability of the models for representing the inelastic response and degradation of confined concrete with high rubber content. Parametric assessments are then undertaken to examine the influence of key material and geometric parameters, including the rubber content, material strength and cross-section properties, on the inelastic large deformation behaviour. The results of the parametric studies are used to quantify the main response parameters, with focus on the member stiffness, moment-axial strength interaction, local buckling criteria and other ductility measures. Based on the findings, modifications are proposed to current design procedures in order to provide a reliable prediction of the inelastic cyclic response characteristics of rubberised concrete filled circular steel tubes. Apart from providing experimentally validated numerical approaches that can be used in future
Ding X, Liapopoulou M, Elghazouli AY, 2024, Seismic response of non-structural components in multi-storey steel frames, Journal of Constructional Steel Research, Vol: 213, ISSN: 0143-974X
This paper investigates the elastic and inelastic seismic response of non-structural components in multi-storey steel moment framed structures and derives predictive relationships for their displacements and spectral accelerations. Within 38 primary structural steel frames, non-structural components characterised by various periods and strength reduction factors, are modelled as single-degree-of-freedom systems which are fixed to individual floors. The primary structures are three, five, and seven-storey steel moment-resisting frames, designed according to the provisions of Eurocode 8. Detailed nonlinear time history analyses are conducted, employing a large set of 100 ground motion records from both far-field and near-field sources. These records are scaled to two distinct levels to simulate the response of primary structures in both elastic and inelastic states. The influence of the ground motion type and the inelasticity level in the non-structural components is examined in detail. The sensitivity to strain hardening and viscous damping considerations is also assessed and discussed. Based on the results, representative relationships for predicting the inelastic displacement ratios are proposed. In addition, various provisions stipulated in European design guidance for determining the spectral accelerations are critically evaluated and improvements are suggested with due consideration for the inelasticity of both the non-structural components and the primary structures.
Elzeadani M, Bompa DV, Elghazouli AY, 2024, Axial compressive behaviour of composite steel elements incorporating rubberised alkali-activated concrete, Journal of Constructional Steel Research, Vol: 212, ISSN: 0143-974X
This study presents an experimental and numerical investigation into the axial compressive behaviour of steel tubes infilled with rubberised alkali-activated concrete. An experimental programme involving circular and square concrete filled steel tubes with different length-to-diameter or length-to-width ratios and concrete infill mix designs with varying rubber contents, of up to 60% crumb rubber replacement of natural aggregates, is firstly described. A detailed account of the experimental results, including the axial capacity, stiffness, toughness, ductility, stress-strain response, and failure patterns, is given. The numerical study is performed in ABAQUS/CAE and the concrete compressive behaviour is modelled using the Concrete Damaged Plasticity model with a modified function for the compressive behaviour. The numerical results are validated against the experimental results, and a parametric study involving 315 finite element models is carried out to cover a wide range of concrete and steel material properties and different steel tube dimensions. The results show that an increase in rubber content in the concrete infill leads to a reduction in the axial capacity; however, this reduction is lower than that observed for unconfined specimens. The results also illustrate an increase in ductility with higher rubber content, which is mainly noticeable for members with circular sections as compared to those with square sections. The experimental and numerical results are used to examine the axial capacity prediction approaches in Eurocode 4 and AISC 360, with particular focus on assessing the confinement effects. It is shown that codified prediction equations for square concrete filled steel tubes give reasonably accurate results. Both codes, however, result in poor predictions for circular concrete filled steel tubes, with Eurocode 4 leading to unsafe predictions while AISC 360 gives overly conservative estimates. Modifications to Eurocode 4 and AISC 360 axial capacit
Elzeadani M, Bompa DV, Elghazouli AY, 2023, Compressive behaviour of FRP-confined rubberised alkali-activated concrete, Construction and Building Materials, Vol: 409, ISSN: 0950-0618
This paper presents experimental and numerical assessments into the compressive stress-strain behaviour of circular FRP-confined rubberised alkali-activated concrete with unidirectional sheets incorporating fibres in the hoop direction. The parameters investigated in the experimental programme include three different rubber contents of 0%, 30% and 60% volumetric replacement of the total natural aggregates and three confinement levels of 1–3 aramid FRP layers. The numerical assessment is performed in ABAQUS/CAE and a new strain hardening-softening function is developed for the compressive behaviour in the Concrete Damaged Plasticity material model, which captures the passive confinement imparted by the FRP jacket on the rubberised concrete. The numerical results are validated against the experimental results and a parametric study involving 240 models covering a wide range of parameters, including varying FRP materials (basalt, glass, aramid, and carbon), reference concrete grades, rubber replacement ratios, and confinement levels, is performed. The experimental results show an increase in the confinement effectiveness, i.e., confined-to-unconfined strength, by 66.7% and 103.4% for specimens with 0% and 60% crumb rubber replacement ratio, respectively, as the number of FRP layers increase from 1 to 3. Test specimens with 0% and 60% crumb rubber replacement ratio indicate an increase in the ultimate axial strain by 228.2% and 76.2%, respectively, as the number of FRP layers increase from 1 to 3. The observed hoop rupture strain reduces by 32.8% and 21.3% for specimens with 0% and 60% crumb rubber replacement ratio as the number of FRP layers increase from 1 to 3, showing a trend of reduction in the hoop rupture strain with higher FRP confinement layers and rubber content. The numerical results show that the enhancement in compressive strength is linearly proportional to the confinement ratio and is only marginally influenced by the FRP jacket stiffness at a give
Elzeadani M, Bompa DV, Elghazouli AY, 2023, Creep Response of Rubberized Alkali-Activated Concrete, Journal of Materials in Civil Engineering, Vol: 35, ISSN: 0899-1561
This study examines the creep deformations and long-term strength properties of rubberized one-part alkali-activated concrete with relatively high rubber content, which have not been previously reported. The aluminosilicate precursors used in the mix design are blast furnace slag and fly ash at a ratio of 4-to-1, while anhydrous sodium metasilicate is used as the solid activator. Crumb rubber particles are used to replace 30% and 60% by volume of the total natural aggregates, and a nonrubberized one-part alkali-activated concrete mix is also prepared for comparison purposes. The creep specimens are subjected to two levels of sustained loads, representing 10% and 20% of the 28-day compressive strength. The creep loads are applied after 28 days of ambient curing, and creep deformations are monitored for a period of 1 year. The results clearly show a deterioration in mechanical properties with higher rubber content, regardless of the testing age. The compressive strength and elastic modulus of the unloaded and loaded creep specimens, tested at an age of 393 days, are generally lower than that observed for similar specimens tested at 28 days. The axial and lateral crushing strains of the specimens tested at 393 days are significantly higher than their counterparts tested at 28 days. The creep strains, measured over 365 days, increase as the applied stress level increases, but reduce with higher rubber content. The creep coefficients and specific creep values of the tested specimens over 365 days experience a reduction as the applied stress level increases, while the opposite is seen as the rubber content increases. The creep coefficients of rubberized one-part alkali-activated concrete are generally higher than those given by prediction models in various codes for conventional concrete. The rate of creep development is also more significant than conventional concrete and does not show signs of slowing down after 365 days of sustained loading.
Elghazouli AY, Bompa DV, Mourad SA, et al., 2023, Ultimate in-plane shear behaviour of clay brick masonry elements strengthened with TRM overlays, Bulletin of Earthquake Engineering, Vol: 21, Pages: 6273-6315, ISSN: 1570-761X
This paper studies the response of unreinforced masonry (URM) members made of hydraulic lime mortar and fired clay bricks, commonly found in heritage structures, strengthened with textile reinforced mortar (TRM) overlays. The investigation includes URM and TRM-strengthened diagonal compression tests on square panels, and relatively large-scale wall specimens subjected to combined gravity and lateral cyclic loads. Complementary compression, tension, and interface material tests are also carried out. The diagonal panel tests show that the TRM effectiveness depends in a non-proportional manner on the overlays, render thickness, and substrate strength. The enhancement in stiffness, strength, and ultimate shear strain, using one to four mesh layers on each side, is shown to vary in the range of 49–132%, 102–536%, and 300–556% respectively. It is shown that strut crushing typically governs the response of such low-strength URM masonry elements confined by TRM overlays. The cyclic tests on the comparatively larger walls show that the TRM is effective, shifting the response from URM diagonal tension to rocking, and enhancing the stiffness, strength, and ultimate drift capacity by more than 160%, 30%, and 130%, respectively. It is shown that analytical assessment methods for predicting the response of TRM-strengthened and URM members in terms of stiffness, strength and load-deformation can be reliably adapted. The cumulative contribution of the URM and TRM components, in conjunction with a suitable fibre textile strain, is also found to offer an improved prediction of the shear strength compared to codified procedures. The findings enable the evaluation and improvement of analytical models for determining the main inelastic response parameters of TRM-strengthened masonry and provide information for validating future detailed nonlinear numerical simulations.
Demonceau JF, Golea T, Elghazouli A, et al., 2023, The FAILNOMORE project – Practice-oriented design recommendations against progressive collapse in steel and steel-concrete buildings, Eurosteel 2023 Conference
Elghazouli A, Bompa DV, Elzeadani M, 2023, Axial behaviour of steel tubes infilled with rubberised alkali-activated concrete, Eurosteel 2023 Conference
Burak S, Bravo-Haro M, Elghazouli A, 2023, Modelling and response of composite steel-concrete members under cyclic loading, Eurosteel 2023 Conference
Bompa D, Elghazouli AY, 2023, Drift Capacity of Textile Reinforced Mortar Masonry Walls, SECED 2023 Conference”, Earthquake Engineering and Dynamics for a Sustainable Future
Lubkowski Z, Elghazouli A, 2023, Potential Impacts of Changes in Eurocode 8 on Design in the UK, SECED 2023 Conference, Earthquake Engineering and Dynamics for a Sustainable Future
Elzeadani M, Bompa DV, Elghazouli A, 2023, Cyclic and Impact properties of Rubberised Alkali-Activated Concrete, SECED 2023 Conference, Earthquake Engineering and Dynamics for a Sustainable Future
Martinez-Paneda M, Elghazouli A, 2023, Novel Large Damping Approaches for Efficient Tall Building Design, SECED 2023 Conference, Earthquake Engineering and Dynamics for a Sustainable Future
Cuka R, Martinez-Paneda M, Elghazouli AY, 2023, Influence of Strong Motion and System Characteristics on the Behaviour of Integrated Damping Techniques, SECED 2023 Conference, Earthquake Engineering and Dynamics for a Sustainable Future
Liapopoulou M, Stafford PJ, Elghazouli AY, 2023, Comparative Assessment of Steel Moment Frames Designed to Eurocode 8, SECED 2023 Conference, Earthquake Engineering and Dynamics for a Sustainable Future
Ding X, Liapopoulou M, Elghazouli AY, 2023, Seismic Response Prediction for Nonstructural components in Multi-storey Structures, SECED 2023 Conference, Earthquake End Dynamics for a Sustainable Future
Khalil ZIM, Stafford PJ, Elghazouli AY, 2023, Dynamic characteristics of jacket-supported offshore wind turbines, SECED 2023 Conference: Earthquake Engineering & Dynamics for a Sustainable Future
Sahin B, Elghazouli AY, 2023, Performance of Reinforced Concrete Buildings in the 2023 Kahramanmaras Earthquakes, SECED 2023, Earthquake Engineering and Dynamics for a Sustainable Future
Bompa D, Elghazouli AY, Bogdan T, et al., 2023, Ultimate Response Characteristics of Steel RBS Connections with Jumbo Sections, SECED 2023, Earthquake Engineering and Dynamics for a Sustainable Future
Elzeadani M, Bompa DV, Elghazouli AY, 2023, Compressive and splitting tensile impact properties of rubberised one-part alkali-activated concrete, Journal of Building Engineering, Vol: 71, Pages: 1-27, ISSN: 2352-7102
This paper presents an experimental assessment of the compressive and splitting tensile properties of rubberised one-part alkali-activated concrete under quasi-static and low-velocity impact loading. An optimised mix design, employing blast furnace slag and fly ash as precursors and anhydrous sodium metasilicate as a solid activator, is used as a reference. Rubber contents of up to 60% volumetric replacement of total natural aggregates are considered. Quasi-static tests are performed using servo-hydraulic machines, whilst the impact tests are performed in an instrumented drop-weight loading rig. Digital image correlation is used to get displacement measurements under both quasi-static and impact loading conditions. Three impact velocities of 5, 10, and 15 m/s are considered, giving rise to strain-rates in the range of 3–270 s−1. The quasi-static results show shape- and size-dependency and characteristically lower compressive and splitting tensile strengths with higher rubber content. The dynamic properties are notably influenced by the rubber content, with a higher ratio resulting in greater impact duration under compressive loading, reduced peak compressive strength, and reduced peak splitting tensile strength. The shape of the stress-strain response under compressive loading changes with rubber addition, showing two major peaks as opposed to a single peak for the non-rubberised specimens. The dynamic mechanical properties are also strain-rate dependent, exhibiting an increase with higher strain-rates. The rubberised specimens exhibit higher strain-rate sensitivity in splitting tension than compression, signified by higher dynamic increase factors for a given strain-rate and lower critical transition strain-rates. A higher rubber content in the mix also result in reduced critical transition strain-rates for the compressive strength, axial crushing strain, and splitting tensile strength. Based on the results of this study, analytical expressions are prov
Shen M-H, Chung K-F, Elghazouli AY, 2023, Performance of stud shear connections under combined shear and pull-out forces, STRUCTURES, Vol: 51, Pages: 415-434, ISSN: 2352-0124
Bompa DV, Elghazouli AY, Bogdan T, et al., 2023, Inelastic cyclic response of RBS connections with jumbo sections, Engineering Structures, Vol: 281, Pages: 1-23, ISSN: 0141-0296
This paper examines the cyclic performance of reduced beam section (RBS) moment connections incorporating larger member sizes than those allowed in the current seismic provisions for prequalified steel connections, through experimentally validated three-dimensional nonlinear numerical assessments. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from two test series, including four full-scale RBS connections comprising large structural members, outside the prequalification limits. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, parametric investigations are undertaken. Particular attention is given to assessing the influence of the RBS-to-column capacity ratio as well as the RBS geometry and location on the overall response. The numerical results and test observations provide a detailed insight into the structural behavior, including strength, ductility, and failure modes of large RBS connections. It is shown that connections which consider sections beyond the code limits, by up to two times the weight or beam depth limits, developed a stable inelastic response characterized by beam flexural yielding and inelastic local buckling. However, connections with very large beam sections, up to three-times the typically prescribed limits, exhibited significant hardening resulting in severe demands at the welds, hence increasing susceptibility to weld fracture and propagation through the column. The findings from this study point to the need, in jumbo sections with thick flanges, for a deeper RBS cut than currently specified in design, to about 66% of the total beam width. This modification would be required to promote a response governed by extensive yielding at the RBS while reducing the excessive strain demands at the beam-to-column welds. Moreover, for connections incorporating relatively deep columns, it is shown that more stringen
Elzeadani M, Bompa DV, Elghazouli AY, 2023, Monotonic and cyclic constitutive behaviour of rubberised one-part alkali-activated concrete, Construction and Building Materials, Vol: 368, Pages: 1-22, ISSN: 0950-0618
This study presents an experimental assessment into the monotonic and cyclic compressive stress-strain rate-dependent response of rubberised one-part alkali-activated concrete. Three different volumetric crumb rubber replacement ratios of total natural aggregates (0%, 30% and 60%), and three different strain rates accounting for quasi-static, moderate seismic and severe seismic conditions are considered. The results indicate a reduction in the elastic modulus, compressive strength, and crushing energy in proportion to the rubber content regardless of the strain rate or loading condition, monotonic or cyclic. A reduction in the axial crushing strain is also obtained with the increase in rubber content within the ranges considered. The increase in strain rate leads to a proportional enhancement in elastic modulus, compressive strength, and axial crushing strain. Under cyclic conditions, the unloading and reloading branches of the stress-strain response fall within the monotonic curves. The cumulative energy dissipation from each first cyclic loop reduces with the increase in rubber content, whilst an increase in the loading rate results in a proportional increase in the cumulative energy dissipation. The unloading modulus is shown to be sensitive to the unloading strain, rubber content and strain rate, while the plastic residual strain is mainly influenced by the unloading strain. Analytical expressions to predict the reduction in elastic modulus, compressive strength, axial crushing strain, unloading modulus and plastic residual strain, with varying rubber contents and for the different strain rates considered, are proposed. Constitutive models representing the monotonic stress-strain response of rubberised alkali-activated concrete materials, as well as the unloading and reloading branches of the cyclic stress-strain response, are also given. Finally, formulations for the strain rate-dependent dynamic increase factors for the elastic modulus, compressive strength, a
Bompa D, Elghazouli A, 2023, Connections of reinforced concrete beams or flat slabs to steel columns using shear keys, Design of Hybrid Structures: Where Steel Profiles Meet Concrete, Pages: 271-336, ISBN: 9780367712075
Hybrid connections between steel columns and reinforced concrete beams or flat slabs may be required due to design constraints or constructional considerations. This chapter presents a unified design procedure for hybrid connections provided with steel shear keys that are welded to the column and fully integrated into the concrete floor. The procedure, based on the fundamentals of European design provisions, includes design expressions for assessing the bending and shear resistances of various regions of connections to beams, as well as for determining the flexural and punching shear capacities of hybrid flat-slab configurations. In addition, detailed requirements for each specific region of the connection are included. Recommendations are also given for determining shear-key dependent parameters, such as the embedment length and cross-section size. The design procedure was validated against an extensive database of tests and numerical models and is suitable for effective practical application.
Bakkar AR, Elyamani A, El-Attar AG, et al., 2023, Dynamic characterisation of a heritage structure with limited accessibility using ambient vibrations, Buildings, Vol: 13, Pages: 1-23, ISSN: 2075-5309
Historic Cairo has been a UNESCO World Heritage Site since 1979. It has more than 600 historic structures, which require extensive studies to sustain their cultural, religious, and economic values. The main aim of this paper is to undertake dynamic investigation tests for the dome of Fatima Khatun, a historic mausoleum in Historic Cairo dating back to the 13th century and consisting of mainly bricks and stones. The challenge was that the structure was difficult to access, and only a small portion of the top was accessible for the attachment of accelerometers. Current dynamic identification procedures typically adopt methods in which the sensors are arranged at optimal locations and permit direct assessment of the natural frequencies, mode shapes, and damping ratios of a structure. Approaches that allow for the evaluation of dynamic response for structures with limited accessibility are lacking. To this end, in addition to in situ dynamic investigation tests, a numerical model was created based on available architectural, structural, and material documentation to obtain detailed insight into the dominant modes of vibration. The free vibration analysis of the numerical model identified the dynamic properties of the structure using reasonable assumptions on boundary conditions. System identification, which was carried out using in situ dynamic investigation tests and input from modelling, captured three experimental natural frequencies of the structure with their mode shapes and damping ratios. The approach proposed in this study informs and directs structural restoration for the mausoleum and can be used for other heritage structures located in congested historic sites.
Elzeadani M, Bompa DV, Elghazouli AY, 2023, Creep Response of Rubberised One-Part Alkali-Activated Concrete, Pages: 298-308, ISSN: 2366-2557
This paper presents the creep deformations and long-term constitutive behavior of rubberised one-part alkali-activated concrete. Blast furnace slag and fly ash are used as the main and secondary aluminosilicate precursor, respectively, while anhydrous sodium metasilicate is employed as a solid activator. Crumb rubber particles are used to replace up to 60% by volume of the total natural aggregates. Specimens are allowed to cure at ambient conditions for 28 days, and the creep specimens are then subjected to two compressive stress levels of 10 and 20% of the 28-day strength, which are sustained for a period of one-year. Results show a deterioration in the compressive strength and elastic modulus with higher rubber content. The long-term strength properties of the creep specimens and their unloaded counterparts are lower than similar specimens tested at 28 days. The axial and lateral crushing strains of the specimens tested at the end of the creep test are higher than similar specimens tested at 28 days. The creep strains increase as the creep load increases but reduce with higher rubber content. The specific creep and creep coefficients show a reduction as the creep load increases from 10 to 20% of the 28-day compressive strength but increase as the rubber content increases. The creep coefficients of the non-rubberised specimens are significantly higher than those given by design equations in the CEB-FIP Model Code 2010, while the opposite is seen for specimens with high rubber content.
Mujdeci A, Guo YT, Bompa DV, et al., 2022, Axial and bending behaviour of steel tubes infilled with rubberised concrete, Thin-Walled Structures, Vol: 181, Pages: 1-18, ISSN: 0263-8231
This paper presents an experimental and numerical study into the behaviour of rubberised concrete-filled steel tubes (RuCFST), incorporating concrete with relatively high rubber replacements of up to 60% of mineral aggregates by volume. Axial compression, eccentric compression, and three-point bending tests on circular specimens are carried out and the results are used to validate the nonlinear procedures adopted in continuum finite element (FE) models of RuCFST members. A constitutive material model specific for confined rubberised concrete and associated modelling techniques, developed from existing procedures for concrete-filled steel tubes (CFST), is proposed for RuCFST members. The modelling techniques involve different damage definitions including low strength concrete with high rubber replacements in compression and bending. It is shown that the proposed modelling procedures can predict reliably the structural behaviour of circular RuCFST members under combined axial-bending conditions. The numerical procedures are then employed in undertaking a detailed parametric assessment for RuCFST cross-sections. The results are used to appraise current design procedures and to propose modifications that provide improved capacity predictions for a wide range of properties and loading conditions.
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