Air-blast-loaded, high-strength concrete beams. Part II: Numerical non-linear analysis

Magnusson, Johan; Ansell, Anders; Hansson, Håkan

doi:10.1680/macr.2010.62.4.235

Cited by 18 publications

(19 citation statements)

References 3 publications

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“…The curves in Figure 9 were chosen as examples of the time span for maximum deflections. Numerical simulations have also been performed on the beams in this figure (Magnusson et al, 2009). The reflected pressures and impulse densities obtained in the air blast tests are presented in Figure 11.…”

Section: Air Blast Testsmentioning

confidence: 99%

“…The air blasts in these tests were of smaller magnitudes than for the bar-reinforced beams and those results are therefore presented and evaluated separately (Magnusson, 1998(Magnusson, , 2006. The present paper is accompanied by a paper on numerical dynamic non-linear modelling of the test results (Magnusson et al, 2009), and there has also been a separate investigation on how to predict support reactions for the concrete beams subjected to air blast loading (Magnusson, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Air-blast-loaded, high-strength concrete beams. Part I: Experimental investigation

Magnusson

Hallgren

Ansell

2010

Magazine of Concrete Research

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The structural behaviour of concrete beams subjected to air blast loading was investigated. Beams of both highstrength concrete (HSC) and normal-strength concrete (NSC) were subjected to air blasts from explosives in a shock tube and for reference were also loaded statically. Concrete with nominal compressive strengths of 40, 100, 140, 150 and 200 MPa were used and a few beams also contained steel fibres. Furthermore, beams with two concrete layers of different strength were tested. All beams subjected to static loading failed in flexure. For some beam types, the failure mode in the dynamic tests differed from the failure mode in the corresponding static tests. In these cases, the failure mode changed from a ductile flexural failure in the static tests to a brittle shear failure in the dynamic tests. Beams without fibres and with high ratio of reinforcement exhibited shear failures in the dynamic tests. It was observed that the inclusion of steel fibres increased the shear strength and the ductility of the beams. The investigation indicates that beams subjected to air blast loading obtain an increased load capacity when compared with the corresponding beams subjected to static loading.

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Section: Air Blast Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Air-blast-loaded, high-strength concrete beams. Part I: Experimental investigation

Magnusson

Hallgren

Ansell

2010

Magazine of Concrete Research

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“…In order to validate the reliability of the numerical model, two numerical analyses of the CTEST20 column (Crawford et al 2012) and B40 beam (Magnusson et al 2010a) under blast loading are conducted and the numerical results are compared with experimental data.…”

Section: Validation Of the Numerical Modelmentioning

confidence: 99%

“…As a result, a RC beam (type B40) tested by Magnusson et al (2010a) that also presented the accurate blast load-time history, is simulated in this section. Some primary geometry parameters of the beam are shown in Fig.…”

Section: B40 Beammentioning

confidence: 99%

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Nonlocal Formulation for Numerical Analysis of Post-Blast Behavior of RC Columns

Zhong

Shi

et al. 2017

Int J Concr Struct Mater

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Residual axial capacity from numerical analysis was widely used as a critical indicator for damage assessment of reinforced concrete (RC) columns subjected to blast loads. However, the convergence of the numerical result was generally based on the displacement response, which might not necessarily generate the correct post-blast results in case that the strain softening behavior of concrete was considered. In this paper, two widely used concrete models are adopted for post-blast analysis of a RC column under blast loading, while the calculated results show a pathological mesh size dependence even though the displacement response is converged. As a consequence, a nonlocal integral formulation is implemented in a concrete damage model to ensure mesh size independent objectivity of the local and global responses. Two numerical examples, one to a RC column with strain softening response and the other one to a RC column with post-blast response, are conducted by the nonlocal damage model, and the results indicate that both the two cases obtain objective response in the post-peak stage.

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Shear in concrete structures subjected to dynamic loads

Magnusson¹,

Hallgren

Ansell

2014

Structural Concrete

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IntroductionDynamic loads such as explosions can cause severe damage to concrete structures. An explosion in air is the result of detonating explosive charges, the rapid combustion of a fuel-air mixture or bursting pressure vessels. The explosion generates a blast wave that propagates through the air at supersonic velocity in all directions. As the blast wave strikes an object such as the wall of a building, the pressures are reinforced due to reflections. In a case where the reflected pressures are sufficiently high, local failures of structural elements such as loadbearing walls or columns can occur. In the design of concrete structures to resist the effects of blast loads, impacts or other severe dynamic loads, it is not practical to consider a structural response in the elastic range only. The structural elements should therefore be allowed to deform plastically, which better utilizes their energy-absorbing capabilities. A certain amount of damage, i.e. concrete cracking and yielding of the reinforcement due to flexure, is therefore usually accepted in the design of structures to resist blast loads. Structural elements should generally be designed for a flexural response. However, real events [1] have shown that highly intense loads from blasts at close range can cause local shear failures in concrete structures, which is a brittle mode of failure. In the Oklahoma City bombing, two concrete columns were reported to have failed in shear. Apart from real events, shear failures in concrete elements have also been observed experimentally in several investigations involving blast and impact loads [2][3][4][5][6][7]. In several cases these tests confirm that elements that fail in flexure under a slowly applied (quasi-static) load may fail in shear under dynamic loads.The purpose of the present paper is to conduct a review of the literature on the shear problem of reinforced concrete structures subjected to intense dynamic loads and to identify areas for further research. In this context, dynamic loads refer to intense events due to explosions and impacts. The review focuses on behavioural aspects of dynamic shear and on the parameters that control the mode of failure. Highlighting the initial response of concrete elements under dynamic loads represents another focus. The modes discussed here are flexural shear and direct shear. A third mode of shear failure is punching shear. This type of failure can occur as an object impacts on a concrete surface with inclined shear cracks and the formation of a conical shear plug through the thickness of the concrete element [8]. However, dynamic punching shear is outside the scope of this paper. 2Quasi-static shear Shear failure in reinforced concrete elements can generally be related to flexural shear and direct shear. In principle, flexural shear and direct shear exhibit similar fundamental behaviour since they share many features such as the mechanisms that transfer shear across a crack. These mechanisms are friction, aggregate interlock and the dowel action of the longitudi...

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Air-blast-loaded, high-strength concrete beams. Part II: Numerical non-linear analysis

Cited by 18 publications

References 3 publications

Air-blast-loaded, high-strength concrete beams. Part I: Experimental investigation

Air-blast-loaded, high-strength concrete beams. Part I: Experimental investigation

Nonlocal Formulation for Numerical Analysis of Post-Blast Behavior of RC Columns

Shear in concrete structures subjected to dynamic loads

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