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1.
Retrofitting of RC Slabs Against Explosive Loads 总被引：1，自引：0，他引：1
OEHLERS Deric John 《天津大学学报(英文版)》2006,12(Z1)
With the increase of terrorist bomb attacks on buildings, there is a need to develop advanced retrofitting techniques to strengthen structures against blast loads. Currently, several guidelines including an Australian version for retrofitting reinforced concrete (RC) structures are available for the design of retrofitting systems against seismic and monotonic loads using steel or fibre reinforced polymer (FRP) plates that can be either adhesively bonded to the surface or near surface mounted to the concrete cover. However, none of these guidelines provide advice suitable for retrofitting structures subjected to blast loads. In this paper, numerical models are used to simulate the performance of retrofitted RC slabs subjected to blast loads. Airblast pressure distributions on the surface of the slabs estimated in a previous study are used as input in the analysis. A material damage model developed previously for concrete and an elastoplastic model for steel bars are employed in this research for modelling reinforced concrete behaviour due to explosive loads. The material models and blast loading are coded into a finite element computer program LS-DYNA3D to do the analysis. With the numerical model, parametric studies are conducted to investigate RC slabs retrofitted by either externally bonded or near-surface mounted plates or GFRP sheets subjected to blast loads. Discussion is made on the effectiveness of the retrofitting system for RC slabs against blast loads. 相似文献
2.
In Order to reduce economic and life losses due to terrorism or accidental explosion threats,reinforced concrete(RC)slabs of buildings need to be designed or retrofitted to resist blast loading.In this paper the dynamic behavior Of RC slabs under blast loading and its influencing factors are studied.The numerical model of an RC slab subjected to blast loading is established using the explicit dynamic analysis software.Both the strain rate effect and the damage accumulation are taken into account in the material model.The dynamic responses of the RC slab subiected to blast loading are analyzed,and the influence of concrete strength,thickness and reinforcement ratio on the behavior of the RC slab under blast loading iS numerically investigated.Based on the numerical results.some principles for blast-resistant design and retrofitting are proposed to improve the behavior of the RC slab subjected to blast loading. 相似文献
3.
Evaluation of blast-resistant performance predicted by damaged plasticity model for concrete 总被引：2，自引：0，他引：2
In order to evaluate the capacity of reinforced concrete (RC) structures subjected to blast loadings,the damaged plasticity model for concrete was used in the analysis of the dynamic responses of blast-loaded RC structures,and all three failure modes were numerically simulated by the finite element software ABAQUS.Simulation results agree with the experimental observations.It is demonstrated that the damaged plasticity model for concrete in the finite element software ABAQUS can predict dynamic responses and typical flexure,flexure-shear and direct shear failure modes of the blast-loaded RC structures. 相似文献
4.
ZHOU Xiaoqing HAO Hong KUZNETSOV Valerian A WASCHL John 《天津大学学报(英文版)》2006,12(B09):94-99
In the present paper, a dynamic plastic damage model for concrete has been employed to estimate responses of a reinforced concrete slab subjected to blast loading. The interaction between the blast wave and the concrete slab is considered in 3D simulation. In the first stage, the initial detonation and blast wave propagation is modelled in 2D simulation before the blast wave reaches the concrete slab, then the results obtained from 2D calculation are remapped to a 3D model. The calculated blast load is compared with that obtained from TM5-1300. Numerical results of the concrete slab response are compared with the explosive test carried out-in the Weapons System Division, Defence Science and Technology Organisation, Department of Defence, Australia. 相似文献
5.
In the present paper, a dynamic plastic damage model for concrete has been employed to estimate responses of a reinforced concrete slab subjected to blast loading. The interaction between the blast wave and the concrete slab is considered in 3D simulation. In the first stage, the initial detonation and blast wave propagation is modelled in 2D simulation before the blast wave reaches the concrete slab, then the results obtained from 2D calculation are remapped to a 3D model. The calculated blast load is compared with that obtained from TM5-1300. Numerical results of the concrete slab response are compared with the explosive test carried out- in the Weapons System Division, Defence Science and Technology Organisation, Department of Defence, Australia. 相似文献
6.
In this study, the effect of steel fibers coated with chemically reactive enamel (CRE) on the system response of concrete structures with reinforcing bars has been investigated for the first time. In particular, the ultimate strength, ductility, and failure mechanism of 24 reinforced concrete slabs were experimentally characterized under static and blast loads. CRE coating applied on steel bars reduced the crater area of slabs under blast loads by up to 20%; it slightly increased the strength of slabs and significantly reduced the strength degradation of slabs when increasingly deflected under static loads, making the slabs more ductile. CRE coating applied on steel fibers increased the strength of slabs by up to 16% under static loads. The influence of CRE coating applied on both steel fibers and bars may be taken into account by introducing a coating factor in the range of 0.57<β<1.0 in the American Concrete Institute (ACI) development length equation. 相似文献
7.
The grisliness after-effects can be induced by explosion accident with the collapsing of the structures, the demolishing of the equipments and the casualty of the human beings. Isolation belt constructed between the blast point and the construction is one of the useful design schemes for blast resistance. The nonlinear procedure ANSYS/LSDYNA970 is used to simulate the contact detonation and the isolation belt of blast resistance filled with the air or water respectively. The results indicate that the maximal damage can be caused by the contact detonation, and the isolation belt of blast resistent filled with water can reduce the damage greatly. 相似文献
8.
HUAN Shi JIANG Guoping Chen Shengming TANG Xiangqian 《天津大学学报(英文版)》2006,12(B09):158-160
The grisliness after-effects can be induced by explosion accident with the collapsing of the structures, the demolishing of the equipments and the casualty of the human beings. Isolation belt constructed between the blast point and the construction is one of the useful design schemes for blast resistance. The nonlinear procedure ANSYS/LSDYNA970 is used to simulate the contact detonation and the isolation belt of blast resistance filled with the air or water respectively. The results indicate that the maximal damage can be caused by the contact detonation, and the isolation belt of blast resistent filled with water can reduce the damage greatly. 相似文献
9.
Terrorist attacks using improvised explosive devices (IED) can result in unreinforced ma-sonry (URM) wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the per-formance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the perform-ance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elas-toplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads. 相似文献
10.
Terrorist attacks using improvised explosive devices (lED) can result in unreinforced masonry (URM) wall collapse.Protecting URM wall from lED attack is very complicated.An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy.However,mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world.In this palaer,numerical models are used to simulate the performance of aluminum foam protected URM walls subjected to blast loads.A distinctive model,in which mortar and brick units of masonry are discritized individually,is used to model the performance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model.The aluminum foam is modelled by a nonlinear elastoplastic material model.The material models for masonry,aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads.Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads. 相似文献
11.
The blast resistance of structures used in buildings needs to be investigated due to the increased threat of a terrorist attack. The damage done by Composition B or Powergel to steel fibre reinforced reactive powder concrete (SFRPC) panels and ordinary reinforced concrete (RC) panels of equivalent static flexural strength is compared. A 0.5 kg charge was detonated at a distance of 0.1 m from the 1.3 m×1.0 m×0. 1 m (thick) panels, which were simply supported and spaning 1.3m. Dynamic displacement measurements, high-speed video recording and visual examination of the panels for spall and breach were undertaken. The SFRPC panels withstood the bare charge blast better than the reinforced ordinary concrete panels. Neither type of panel was breached using a 0.5 kg charge. The RC panel exhibited more spalling when Composition B was used. Under successive Composition B loading conditions, the RC panel was breached. In comparison the SFRPC panel was not breached. Exposure to fragmenting charge loading conditions confirmed these performance differences between the SFRPC panel and the reinforced ordinary concrete panel. 相似文献
12.
Numerical prediction of statistical masonry wall fragment distribution induced by blast loading 总被引：1，自引：0，他引：1
The hazard caused by the fragments of damaged structures is usually significant in acci-dental explosions or hostile blast events.A reliable and efficient method to estimate probable fragment size,velocity and launch distance will be useful to assess and design countermeasures to mitigate the possible fragment hazards.This paper presents a numerical method for predicting the size and launch distance of the fragments caused by explosive damage of masonry wall.Numerical simulations with different scaled distances are carried out,and the statistical distribution functions of the fragment size and launch distance in terms of the scaled distance are derived. 相似文献
13.
14.
In order to design and retrofit a subway station to resist an internal blast,the distribution of blast loading and its effects on structures should be investigated firstly.In this paper,the behavior of a typical subway station subjected to different internal blast Ioadings was analyzed.It briefly introduced the geometric characteristics and material constitutive model of an existing two-layer and three-span frame subway station.Then three cases of different explosive charges were considered to analyze the dynamic responses of the structure.Finally,the maximum principal stress,displacement and velocity of the columns in the three cases were obtained and discussed.It concluded that the responses of the columns are sensitive to the charge of explosive and the distance from the detonation.It's also found that the stairs between the two layers have significant effects on the distribution of the maximum principal stress of the columns in the upper layer.The explicit dynamic nonlinear finite element software-ANSYS/LS-DYNA was used in this study. 相似文献
15.
EFFECT OF CORROSION ON BOND BEHAVIOR AND BENDING STRENGTH OF REINFORCED CONCRETE BEAMS 总被引：1，自引：0，他引：1
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅｉｓｇｒｏｗｉｎｇｃｏｎｃｅｒｎｆｏｒｃｏｒｒｏｓｉｏｎｄａｍ ａｇｅｉｎｒｅｉｎｆｏｒｃｅｄｃｏｎｃｒｅｔｅ (ＲＣ)ｓｔｒｕｃｔｕｒｅｓｗｉｔｈｓｅｖｅｒａｌｄｅｃａｄｅｓ’ｓｅｒｖｉｃｅ.Ｔｈｅｒｅｉｎｆｏｒｃｅｍｅｎｔｃｏｒ ｒｏｓｉｏｎｏｆＲＣｃｏｎｓｔｒｕｃｔｉｏｎｓｐｒｏｂａｂｌｙｉｓｔｈｅｍｏｓｔｓｉｇｎｉｆｉｃａｎｔｐｒｏｂｌｅｍａｎｄｏｕｔｗｅｉｇｈｓｏｔｈｅｒｆｏｒｍｓｏｆｄｅｔｅｒｉｏｒａｔｉｏｎ .ＳｔｕｄｉｅｓｂｙＰｅａｔｔｉｅｅｔａｌ.( 1 9… 相似文献
16.
Under extreme loading condition,a shelter will provide a safe place to protect people from injury caused by blast wave and fragments.In order to save resource and reuse waste materi-als,a new design concept for blast protection shelter was explored.The new construction was composed of I-section steel panel or C-channel steel panel filled with recycled concrete aggregate.The compaction process of the recycled concrete aggregate filled in the steel construction was ex-perimentally investigated.A single storey shelter based on the proposed design concept was nu-merically simulated by using LS-DYNA software.In the 3D numerical model,three walls were de-signed using I-section steel and one wall using C-channel steel,and all of the four walls were filled with recycled concrete aggregate.The penetration analysis was done by using ConWep.Some penetration tests were also carried out by using a gas gun.It is found that the proposed shelter based on the design concept is effective for blast protection. 相似文献
17.
Dong-ming Yan Hua-wei Yin Cheng-lin Wu Yan-long Li Jason Baird Gen-da Chen 《浙江大学学报(A卷英文版)》2016,17(9):689-701
In this study, two full-size concrete walls were tested and analyzed to demonstrate the effectiveness of a chemically reactive enamel (CRE) coating in improving their mechanical behavior under blast loading: one with CRE-coated rebar and the other with uncoated rebar. Each wall was subjected in sequence to four explosive loads with equivalent 2, 4, 6-trinitrotoluene (TNT) charge weights of 1.82, 4.54, 13.6, and 20.4 kg. A finite element model of each wall under a close-in blast load was developed and validated with pressure and strain measurements, and used to predict rebar stresses and concrete surface strain distributions of the wall. The test results and visual inspections consistently indicated that, compared with the barrier wall with uncoated reinforcement, the wall with CRE-coated rebar has fewer concrete cracks on the front and back faces, more effective stress transfers from concrete to steel rebar, and stronger connections with its concrete base. The concrete surface strain distributions predicted by the model under various loading conditions are in good agreement with the crack patterns observed during the tests. 相似文献
18.
There is growing concern for corrosion damage in reinforced concrete structures with several decades’ service. Pullout tests
and beam tests were carried out to study the effect of reinforcement corrosion on the bond behavior and bending strength of
reinforced concrete beams. The bond strength of plain bars and concrete initially increases with increasing corrosion, then
declines. The turning point depends on the cracking of the concrete cover. The bond strength of deformed bars and concrete
increases with corrosion up to a certain amount, but with progressive increase in corrosion, the bond strength decreases,
and the cracking of the concrete cover seems to have no effect on the bond strength. On the basis of test data, the bond strength
coefficient recommended here, which, together with the bond strength of uncorroded steel bars and concrete, can be used to
easily calculate the bond strength of corroded steel bars and concrete. The bond strength coefficient proposed in this paper
can be used to study the bond stress-slip relationship of corroded steel bars and concrete. The bending strength of corroded
reinforced concrete beams declines with increasing reinforcement corrosion. Decreased bending strength of corroded RC beam
is due to reduction in steel bar cross section, reduction of yield strength of steel bar, and reduction of bond capacity between
steel bar and concrete.
Project supported by Cao Guanbiao Key Technology Development Founding of Zhejiang University and Construction Ministry of
China. 相似文献
19.
Time-to-cracking of the concrete cover induced by the steel corrosion is one of the critical problems faced by engineers, operators and asset managers in making strategies for the maintenance and repairs of reinforced concrete (RC)structures affected by corrosion. In this paper, a theoretical model for predicting the time-to-cracking is derived by assuming the bond between the steel bar and the concrete as a linear combination of perfectly smooth and bonded. The model takes into account the characteristics of existing exiguous flaws and initial cracks in the concrete before the load acting on RC structures. The validity of the proposed model is preliminarily verified by comparing the obtained results with the available experimental results. A remarkable advantage of the proposed method is its application to the prediction of the service life of RC structures, made of the deformed steel bars as well as the round bars. By determining an experimental constant α, which is related to the interface bond state between the steel bar and the concrete, the service life of RC structures can be predicted using the proposed scheme. Analysis of major factors affecting the time-to-cracking demonstrates that the length of the initial crack affects the service life of RC structures significantly. Moreover, the larger cover thickness and the smaller diameter of the steel bar within a certain range are beneficial to prolonging the time-to-cracking. 相似文献
20.
Abstract： An innovative occupant friendly retrofitting technique has been developed for reinforced concrete （RC） building structures with hollow brick infill wails used as partition walls which constitute the major portion of the existing building stock in Turkey. The idea is to convert the existing hollow brick infill wall into a load carrying system acting as a cast-in-place RC wall by reinforcing it with relatively thin concrete plates bonded to the mortar coated infill wall by use of tile adhesive and fixed by qb6 （6 mm diameter） bolts. Test parameters were the shape and thickness of the plates, presence of reinforcement in plates, number and arrangement of O6 bolts. It was observed that lateral strength, stiffness, energy dissipation capacity, and ductility of the strengthened infill walls were improved and behaviour was enhanced by the proposed technique. Plates with two different basic shapes were used to strengthen the test specimens. 相似文献