Time-history blast response and failure mechanism of RC columns using Lagrangian formulation

Structures ◽  
2021 ◽  
Vol 34 ◽  
pp. 3087-3098
Author(s):  
Chunwei Zhang ◽  
Masoud Abedini
Keyword(s):  
Failure Mechanism ◽  
Time History ◽  
Lagrangian Formulation ◽  
Rc Columns ◽  
Blast Response

Empirical Formulae To Predict Pressure And Impulsive Asymptotes For P–I Diagrams Of RC Columns Strengthened With FRP

2011 ◽  
Author(s):  
A. A. Mutalib ◽  
Norhisham Bakhary
Keyword(s):  
Concrete Strength ◽  
Numerical Results ◽  
Fiber Reinforced Polymer ◽  
Blast Loads ◽  
Fiber Reinforced ◽  
Rc Columns ◽  
Pressure Impulse ◽  
Reinforced Polymer ◽  
Blast Response ◽  
Parametric Studies

Kajian terhadap keupayaan struktur dalam menahan beban letupan menggunakan Fiber Reinforced Polymer (FRP) adalah sangat terhad. Dalam kajian ini, satu analisis terhadap keupayaan FRP bagi menahan beban letupan dilakukan. Tujuan analisis ini adalah untuk memperolehi hubungan antara kekuatan FRP, bilangan lapisan ketebalan FRP dan susunatur FRP bagi menahan kekuatan sesuatu beban letupan. Kajian ini dilakukan mengunakan model tiang diperkukuh dengan FRP yang dibina menggunakan perisian LS–DYNA. Ia melibatkan beberapa siri simulasi untuk meramalkan tindakbalas letupan dan kerosakkan pada tiang sekiranya sesuatu beban letupan dikenakan. Melalui simulasi ini, kekuatan FRP, bilangan lapisan ketebalan FRP dan susunatur FRP dapat ditentukan. melalui keputusan–keputusan yang diperolehi, pressure–impulse diagram (P–I) bagi tiang yang diperkukuhkan dengan FRP dapat dibentuk. Kata kunci: Pengukuhan; beban letupan; FRP; P–I diagrams There are only limited studies that directly correlate the increase in structural capacities in resisting the blast loads with the fiber reinforced polymer (FRP) strengthenin. In this paper, numerical analyses of dynamic response and damage of reinforced concrete (RC) columns strengthened with FRP to blast loads are carried out using the commercial software LS–DYNA. A series of simulations are performed to predict the blast response and damage of columns with different FRP type. The simulations also involved parametric studies by varying the FRP thickness, configuration, different column dimension, concrete strength, and longitudinal and transverse reinforcement ratio. The numerical results are used to develop pressure–impulse (P–I) diagrams of FRP strengthened RC columns. Based on the numerical results, the empirical formulae are derived to calculate the pressure and impulse asymptotes of the P–I diagrams of RC columns strengthened with FRP. Key words: Strengthening; blast loads; FRP; P–I diagrams

Shear Resistant Behavior of RC Columns Subjected to Axial Pulse-Like Ground Motions

2013 ◽  
Vol 639-640 ◽  
pp. 832-835
Author(s):  
Wei Feng Zhao ◽  
Xiao Quan Hu ◽  
Qin Chen
Keyword(s):  
Axial Velocity ◽  
Ground Motions ◽  
Time History ◽  
Load Ratio ◽  
Spectral Ratio ◽  
Shear Capacity ◽  
Velocity Pulse ◽  
Rc Columns ◽  
Shear Span ◽  
Earthquake Records

The shear-resistant behavior of reinforced concrete (RC) columns subjected to axial velocity pulse-like ground motions was studied. Single RC columns with the constant vertical and horizontal fundamental period were used to investigate the influences of fault-distance of earthquake records, vertical to horizontal acceleration spectral ratio of earthquake records, initial axial load ratio and shear span ratio of RC column, on the shear-resistant behavior of RC columns. a suite of 18 strong ground motion records from Chi-chi earthquake divided into three fault-distance groups were taken as excitations to execute nonlinear dynamic time history analysis. The results demonstrated that axial velocity pulse-like earthquake action (fault-distance) had significant influences on the shear resistant-resistant of RC columns. Shear-resistant behavior (shear capacity/shear demand) increases with the increasing of fault-distance. Fault-distance and shear span ratio had a certain coupling influences on the shear-resistant behavior of RC columns.

Elastoplastic Seismic Response Analysis of Masonry Buildings with Variable Wall Thickness along Height

2010 ◽  
Vol 452-453 ◽  
pp. 101-104
Author(s):  
Bai Tao Sun ◽  
Hong Fu Chen
Keyword(s):  
Failure Mechanism ◽  
Wall Thickness ◽  
Time History ◽  
Response Analysis ◽  
Masonry Buildings ◽  
The Finite Element Method ◽  
Variable Wall Thickness ◽  
Variable Wall ◽  
Input Motion ◽  
Lateral Stiffness Ratio

The multistory masonry buildings with variable wall thickness along the height have suffered different degrees of damage subjected to the Wenchuan earthquake. In order to study the failure mechanism of such masonry structure under the earthquake, three types of five-story structure of computational model are firstly introduced in this paper, including (1) the wall thickness of five stories is 240mm; (2) the wall thickness of the first floor is 370mm, and that of the upper four stories is 240mm; (3) the wall thickness of the first and second story is 370mm, and that of the other stories is 240mm. Then, the elastoplastic time-history dynamic analysis is carried on with the story shear model by the finite element method, and the ground motion of El Centro waves are adopted as earthquake input motion. The analysis results show that variation of wall thickness along height can easily cause stiffness mutation of the upper and lower floor, lead to local floor deformation concentration and soft floors, and the change of failure mechanism of the structure. Finally, it is suggested that some appropriate seismic resistance measures should be taken to meet the lateral stiffness ratio of the upper and lower floor in the later design of this structure, or this kind of structure should be avoided using as far as possible.

scholarly journals Large Deflection Behavior Effect in Reinforced Concrete Columns Exposed to Extreme Dynamic Loads

2019 ◽  
Author(s):  
Masoud Abedini ◽  
Lei Shi ◽  
Javad Mehrmashhadi ◽  
Chulin Chen ◽  
Roozbeh Alipour ◽  
...  
Keyword(s):  
Concrete Strength ◽  
Field Tests ◽  
Nonlinear Behavior ◽  
Charge Weight ◽  
Element Analysis ◽  
Rc Columns ◽  
Substantial Impact ◽  
Scaled Distance ◽  
Rc Column ◽  
Blast Response

Reinforced concretes (RC) have been widely used in constructions. In construction, one of the critical elements carrying a high percentage of the weight is columns which were not used to design to absorb large dynamic load like surface bursts. This study focuses on investigating blast load parameters to design more resistant RC columns to blast loads. The numerical model is based on finite element analysis (FEA) using LS-DYNA. Numerical results are validated against blast field tests available online. Couples of simulations are performed with changing blast parameters to study effects of various scaled distances on the nonlinear behavior of RC columns. According to simulation results, the scaled distance has a substantial impact on the blast response of RC columns. With lower scaled distance, higher peak pressure and larger pressure impulse are applied on the RC column. Eventually, keeping the scaled distance unchanged, increasing the charge weight or shorter standoff distance cause more damage to the RC column. Intensive studies are carried out to investigate the effects of scaled distance and charge weight on the damage degree and residual axial load carrying capacity of RC columns with various column width, longitudinal reinforcement ratio and concrete strength. Results of this research will be used to assessment the effect of an explosion on the dynamic behavior of RC columns.

Plasticity Based Approach for Evaluating the Blast Response of RC Columns Retrofitted with FRP

2011 ◽  
Vol 2 (3) ◽  
pp. 367-380 ◽  
Author(s):  
Philip Isaac ◽  
Antony Darby ◽  
Tim Ibell ◽  
Mark Evernden
Keyword(s):  
Rc Columns ◽  
Blast Response

scholarly journals Numerical Evaluation of Reinforced Concrete Columns Retrofitted with FRP for Blast Mitigation

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jing Dong ◽  
Junhai Zhao ◽  
Dongfang Zhang
Keyword(s):  
High Strength ◽  
Element Model ◽  
Blast Mitigation ◽  
Rc Columns ◽  
Existing Structures ◽  
Frp Composites ◽  
Blast Response ◽  
Proposed Model ◽  
Comprehensive Comparison ◽  
Result Analysis

Fiber reinforced polymer (FRP) material is commonly applied in retrofitting structures due to the advantages of high strength and well corrosion resistance. Previous studies indicated that retrofitting with FRP sheet was an effective way for protecting the existing structures to resist the blast loads, but little research made comprehensive comparison study on the blast response of RC columns with different retrofitting strategies. This paper proposed a series of FRP retrofitting strategies and evaluated their effect on blast mitigation using numerical analysis approach. Comparison studies were conducted on the effect of FRP type, FRP thickness, and retrofitting mode on blast mitigation. A finite element model of RC columns retrofitted with FRP under blast loading was developed. The model considered the strain rate effect of steel and concrete and the orthotropic property of FRP composites. The reliability of the proposed model was validated against the data from a field blast test. Based on the verified model, the blast responses of RC columns with different retrofitting strategies were numerically investigated. According to the result analysis, appropriate FRP type, FRP thickness, retrofitting mode, and retrofitting length were recommended.

Failure Behavior of Double-Layer-Domes Subjected to Impact

2020 ◽  
pp. 2150015
Author(s):  
E. Nazari ◽  
B. Shekastehband
Keyword(s):  
Kinetic Energy ◽  
Failure Mechanism ◽  
Double Layer ◽  
Shear Failure ◽  
Progressive Failure ◽  
Time History ◽  
Failure Behavior ◽  
Finite Element Software ◽  
Local Shear ◽  
The Impact

The dynamic failure behavior of double-layer-domes subjected to impact is studied numerically through the nonlinear finite element software LS-DYNA. The parameters considered in this work include the mass, velocity, and size of impactor, impact direction, roof weigh, geometric imperfection, rise-to-span ratio, and depth of dome. The dynamic time-history response and energy conversion of the structure are utilized to distinguish between the failure mechanism types. For the cases studied, it is found that failure of the structures falls into one of the three categories: (1) local shear failure, (2) partial progressive failure, and (3) full progressive failure. Non-failure case dominates the dome response when the kinetic energy of the impactor is small enough, and the structure can convert most of the kinetic energy into the strain energy, thereby absorbing the impact. Local shear failure occurs in a double-layer-dome when an impactor with very high kinetic energy strikes the dome. For an impactor striking with a mass of 5 to 300[Formula: see text]ton and a velocity of 50 to 120[Formula: see text]m/s, the double-layer-dome studied will suffer from partial progressive failure. Varying mass and velocity of the impactor in the range of 1 to 300[Formula: see text]ton and 200 to 400[Formula: see text]m/s, respectively, results in a tendency of the dome to exhibit local shear failure. Although impact direction does not cause a change in the failure mechanism type, there is a reduction in the severity of failure of the system as the impact angle increases. Roof weight has no dominant effect on the failure mechanism of the double-layer-dome. A small initial member imperfection with amplitude 0.001[Formula: see text] does not change the progressive failure type. A large member imperfection of 0.01[Formula: see text] triggers member buckling and leads to local shear failure of the dome. Except for some loading cases, the change in the rise to span ratio and depth of the dome does not seriously affect the failure mode.

Study on Seismic Performance of Infilled Frame of Underlying Weak Layer

2012 ◽  
Vol 204-208 ◽  
pp. 1028-1033
Author(s):  
Guang Yu Lei ◽  
Yu Yao Zeng ◽  
Can Guo Jin
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Failure Mechanism ◽  
Time History ◽  
Element Model ◽  
Frame Structure ◽  
Housing System ◽  
Weak Layer ◽  
Infilled Frame ◽  
Weak Beam

After the Wenchuan earthquake, a large number of infilled frame structure of underlying weak layer (the bottom of non-filled walls, the upper wall of clouds filling) of the housing system did not appear "weak beam strong column" of the failure mode. Established pure frame structure of finite element model which considered the quality of in filled wall without taking into account of its stiffness and strength and the frame of finite element model which contains filler wall, and carried out elastic-plastic time-history analysis with established finite element model of two under earthquake, through analysis and comparison understand reasons which infilled frame structure of underlying weak layer did not achieve the "weak beam strong column" ductile failure mechanism, and further explored how to achieve "weak beam strong column" failure mechanism for infilled frame structure of underlying weak layer, raised a number of assurance measures.

scholarly journals Blast Response of Elevated Water Tank Staging with Metallic Damper

2021 ◽  
Vol 309 ◽  
pp. 01135
Author(s):  
Boda Balaraju ◽  
Atulkumar Manchalwar
Keyword(s):  
Linear Time ◽  
Structural Response ◽  
Time History ◽  
Bending Moment ◽  
Water Tank ◽  
Blast Response ◽  
History Analysis ◽  
Structural Responses ◽  
Elevated Water ◽  
Metallic Damper

In the present paper work an attempt has been made to study the dynamic behaviour of the elevated water tank staging by using x-plate metallic damper subjected to blast induced ground vibrations. The main objective of this study is to reduce the damage of the elevated water tank by providing structural response control devices. The water tank staging is modelled in SAP 2000 and non-linear time history analysis is carried out to know the performance of the metallic damper under four different intensity blast induced ground motions and comparing the performance of structure without damper case. After the completion of analysis, the results show that by using metallic damper bending moment, shear force and displacements are comparatively reduced when compared to the without damper case. From this study observed that metallic x-plate damper is effectively reduced the structural responses under blast excitations.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

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