Numerical Simulation of Polyurethane Strengthened Perforated Masonry Walls under Blast Loading

2013 ◽  
Vol 639-640 ◽  
pp. 727-731
Author(s):  
Yu Rong Guo ◽  
Hong Zheng
Keyword(s):  
Numerical Simulation ◽  
Failure Modes ◽  
Numerical Models ◽  
Time History ◽  
Local Failure ◽  
Masonry Walls ◽  
Layer Number ◽  
Failure Patterns ◽  
Resistance Performance ◽  
Strengthening Method

In order to investigate the explosion resistance performance of perforated masonry walls strengthened with polyurethane, nine numerical models with different layer number and different strip width of polyurethane are established in this paper. Deformation drawings and time history curves of displacement of the numerical models are comparatively analyzed. It is found that there are two failure modes, global failure and local failure, of strengthened masonry walls and the differences of failure patterns are significant between various types of strengthening method.

scholarly journals Study on Impact Damage and Energy Dissipation of Coal Rock Exposed to High Temperatures

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Tu-bing Yin ◽  
Kang Peng ◽  
Liang Wang ◽  
Pin Wang ◽  
Xu-yan Yin ◽  
...  
Keyword(s):  
High Temperatures ◽  
Failure Modes ◽  
Split Hopkinson Pressure Bar ◽  
Impact Damage ◽  
Time History ◽  
Hopkinson Pressure Bar ◽  
Absorbed Energy ◽  
Failure Patterns ◽  
Temperature Conditions ◽  
Coal Rock

The dynamic failure characteristics of coal rock exposed to high temperatures were studied by using a split Hopkinson pressure bar (SHPB) system. The relationship between energy and time history under different temperature conditions was obtained. The energy evolution and the failure modes of specimens were analyzed. Results are as follows: during the test, more than 60% of the incident energy was not involved in the breaking of the sample, while it was reflected back. With the increase of temperature, the reflected energy increased continuously; transmitted and absorbed energy showed an opposite variation. At the temperature of 25 to 100°C, the absorbed energy was less than that transmitted, while this phenomenon was opposite after 100°C. The values of specific energy absorption (SEA) were distributed at 0.04 to 0.1 J·cm−3, and its evolution with temperature could be divided into four different stages. Under different temperature conditions, the failure modes and the broken blocks of the samples were obviously different, combining with the variation of microstructure characteristics of coal at high temperatures; the physical mechanism of damage and failure patterns of coal rock are explained from the viewpoint of energy.

scholarly journals In-Plane Behaviour of Masonry Walls: Numerical Analysis and Design Formulations

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5780
Author(s):  
Thomas Celano ◽  
Luca Umberto Argiento ◽  
Francesca Ceroni ◽  
Claudia Casapulla
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Numerical Models ◽  
Experimental Tests ◽  
Element Model ◽  
Masonry Walls ◽  
Analysis And Design ◽  
Non Linear ◽  
Failure Loads ◽  
Modelling Approaches

This paper presents the results of several numerical analyses aimed at investigating the in-plane resistance of masonry walls by means of two modelling approaches: a finite element model (FEM) and a discrete macro-element model (DMEM). Non-linear analyses are developed, in both cases, by changing the mechanical properties of masonry (compressive and tensile strengths, fracture energy in compression and tension, shear strength) and the value of the vertical compression stress applied on the walls. The reliability of both numerical models is firstly checked by means of comparisons with experimental tests available in the literature. The analyses show that the numerical results provided by the two modelling approaches are in good agreement, in terms of both failure loads and modes, while some differences are observed in their load-displacement curves, especially in the non-linear field. Finally, the numerical in-plane resistances are compared with the theoretical formulations provided by the Italian building code for both flexural and shear failure modes and an amendment for the shape factor ‘b’ introduced in the code formulation for squat walls is proposed.

scholarly journals Influence of Beam-to-Column Linear Stiffness Ratio on Failure Mechanism of Reinforced Concrete Moment-Resisting Frame Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-24
Author(s):  
Jizhi Su ◽  
Boquan Liu ◽  
Guohua Xing ◽  
Yudong Ma ◽  
Jiao Huang
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Numerical Models ◽  
Frame Structures ◽  
Material Strength ◽  
Stiffness Ratio ◽  
Limit Values ◽  
Failure Patterns ◽  
Moment Resisting Frame ◽  
Moment Resisting

The design philosophy of a strong-column weak-beam (SCWB), commonly used in seismic design codes for reinforced concrete (RC) moment-resisting frame structures, permits plastic deformation in beams while keeping columns elastic. SCWB frames are designed according to beam-to-column flexural capacity ratio requirements in order to ensure the beam-hinge mechanism during large earthquakes and without considering the influence of the beam-to-column stiffness ratio on the failure modes of global structures. The beam-to-column linear stiffness ratio is a comprehensive indicator of flexural stiffness, story height, and span. This study proposes limit values for different aseismic grades based on a governing equation deduced from the perspective of member ductility. The mathematical expression shows that the structural yielding mechanism strongly depends on parameters such as material strength, section size, reinforcement ratio, and axial compression ratio. The beam-hinge mechanism can be achieved if the actual beam-to-column linear stiffness ratio is smaller than the recommended limit values. Two 1/3-scale models of 3-bay, 3-story RC frames were constructed and tested under low reversed cyclic loading to verify the theoretical analysis and investigate the influence of the beam-to-column linear stiffness ratio on the structural failure patterns. A series of nonlinear dynamic analyses were conducted on the numerical models, both nonconforming and conforming to the beam-to-column linear stiffness ratio limit values. The test results indicated that seismic damage tends to occur at the columns in structures with larger beam-to-column linear stiffness ratios, which inhibits the energy dissipation. The dynamic analysis suggests that considering the beam-to-column linear stiffness ratio during the design of structures leads to a transition from a column-hinge mechanism to a beam-hinge mechanism.

scholarly journals Numerical Simulation of Failure Characteristics of Reactive Powder Concrete With Steel Fiber

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaohu Zhang ◽  
Songyuan Liu ◽  
Gan Li ◽  
Xiaofei Wang
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Failure Modes ◽  
Steel Fiber ◽  
Numerical Models ◽  
Triaxial Compression ◽  
Mechanical Tests ◽  
Steel Fibers ◽  
Reactive Powder Concrete ◽  
Reactive Powder

Steel fibers were delivered into the numerical concrete specimens using a mixed congruence method. A coplanar projection method is proposed to solve the problem of discriminating the crossing among steel fibers. Numerical models were built for reactive powder concrete (RPC) cylindrical specimens with 1 and 2% steel fiber. Comparisons between the numerical model and actual specimen slices show that the modified method has a good simulation effect. An improved anchor cable unit was used to simulate the bond–slip behavior between the steel fiber and concrete; the drawing of a single steel fiber was simulated. Then, the uniaxial compression, triaxial compression, and three-point bending of RPC specimens with 1% steel fiber were simulated, reproducing the concrete cracking and steel fiber slipping behaviors of RPC specimens. The failure modes of the numerical RPC specimen under various mechanical tests are consistent with the experimental results, proving the practicability and accuracy of this established numerical model. This study provides a foundation for the numerical simulation of RPC properties.

scholarly journals Seismic Performance of Clay Bricks Construction

2020 ◽  
Vol 6 (4) ◽  
pp. 785-805
Author(s):  
Jabbar Abdalaali Kadhim ◽  
Abbass Oda Dawood
Keyword(s):  
Seismic Performance ◽  
Numerical Models ◽  
Computer Software ◽  
Time History ◽  
Masonry Walls ◽  
Clay Bricks ◽  
Masonry Construction ◽  
South Of Iraq ◽  
Nonlinear Dynamic Analyses ◽  
Nonlinear Time History

The extensive use of masonry construction accompanied by the seismic hazard in Iraq requires comprehensive studies to assess the seismic performance of such construction. This study aims to evaluate the seismic performance of URM and CM buildings by their nonlinear time-history responses. ANSYS 18.2 software has been used to perform the nonlinear dynamic analyses. The mechanical properties have been investigated as the first step of the study. A simple mechanical instrument was improvised to determine the tensile strength of masonry directly. Ground motions were chosen in a manner so that their peak ground accelerations and site soils are as similar as possible to those in the South of Iraq. The computer software terminated all the analyses before the ends of the applied earthquake duration because of the solutions did not converge. In the numerical models, severe cracks have been observed in both URM and CM models, indicating their unsafe seismic performance. The minor cracks in confining concrete in the CM model compared to the severe ones in the masonry walls of the same model show the capability of the confinement to prevent the disintegration of collapsed masonry walls, at least in damaging cases like the building state at the solution termination.

scholarly journals Use of bolted shear connectors in composite construction

2018 ◽  
Author(s):  
Xianghe Dai ◽  
Dennis Lam ◽  
Therese Sheehan ◽  
Jie Yang ◽  
Kan Zhou
Keyword(s):  
Numerical Simulation ◽  
Composite Beam ◽  
Failure Modes ◽  
Numerical Models ◽  
High Strength ◽  
Shear Behaviour ◽  
Composite Construction ◽  
Structural Behaviour ◽  
Shear Connectors ◽  
Shear Connection

Composite beam incorporated steel profiled decking has been extensively used for multi-storey buildings and is now one of the most efficient and economic form of flooring systems. However, the current composite flooring system is not demountable and would require extensive cutting on site during demolition, and the opportunity to reuse the steel components is lost even though these components could be salvaged and recycled. This paper presents the use of high strength bolts as shear connectors in composite construction, the shear behaviour and failure modes were observed and analysed through a series of push-off tests and numerical simulation. The results highlighted the structural behaviour of three different demountable shear connection forms in which continuous slabs or un-continuous slabs were used. Numerical models were validated against experimental observation. Both experimental and numerical results support the high strength bolts used as demountable shear connectors and lead to a better understanding to the behaviour of this form of shear connectors.

Vulnerability-Based Design of Sliding Concave Bearings for the Seismic Isolation of Steel Storage Tanks

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Silvia Alessandri ◽  
Phuong Hoa Hoang
Keyword(s):  
Liquid Steel ◽  
Seismic Isolation ◽  
Failure Modes ◽  
Fragility Curves ◽  
Time History ◽  
Probability Of Failure ◽  
Design Parameters ◽  
Economic Losses ◽  
Storage Tanks ◽  
Isolation System

Liquid steel storage tanks are strategic structures for industrial facilities and have been widely used both in nuclear and non-nuclear power plants. Typical damage to tanks occurred during past earthquakes such as cracking at the bottom plate, elastic or elastoplastic buckling of the tank wall, failure of the ground anchorage system, and sloshing damage around the roof, etc. Due to their potential and substantial economic losses as well as environmental hazards, implementations of seismic isolation and energy dissipation systems have been recently extended to liquid storage tanks. Although the benefits of seismic isolation systems have been well known in reducing seismic demands of tanks; however, these benefits have been rarely investigated in literature in terms of reduction in the probability of failure. In this paper, A vulnerability-based design approach of a sliding concave bearing system for an existing elevated liquid steel storage tank is presented by evaluating the probability of exceeding specific limit states. Firstly, nonlinear time history analyses of a three-dimensional stick model for the examined case study are performed using a set of ground motion records. Fragility curves of different failure modes of the tank are then obtained by the well-known cloud method. In the following, a seismic isolation system based on concave sliding bearings is proposed. The effectiveness of the isolation system in mitigating the seismic response of the tank is investigated by means of fragility curves. Finally, an optimization of design parameters for sliding concave bearings is determined based on the reduction of the tank vulnerability or the probability of failure.

Resistance of Reinforced Concrete Frames with Masonry Infill Walls to In-Plane Vertical Loading

2016 ◽  
Vol 711 ◽  
pp. 982-988
Author(s):  
Alex Brodsky ◽  
David Z. Yankelevsky
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Progressive Collapse ◽  
Lateral Loading ◽  
Masonry Walls ◽  
Reinforced Concrete Frame ◽  
Masonry Infill ◽  
Concrete Frame ◽  
Vertical Loading ◽  
Infill Masonry

Numerous studies have been conducted on the in plane behavior of masonry infill walls to lateral loading simulating earthquake action on buildings. The present study is focused on a problem that has almost not been studied regarding the vertical (opposed to lateral) in-plane action on these walls. This may be of concern when a supporting column of a multi-storey reinforced concrete frame with infill masonry walls undergoes a severe damage due to an extreme loading such as a strong earthquake, car impact or military or terror action in proximity to the column. The loss of the supporting column may cause a fully or partly progressive collapse to a bare reinforced concrete frame, without infill masonry walls. The presence of the infill masonry walls may restrain the process and prevent the development of a progressive collapse. The aim of the present study is to test the in-plane composite action of Reinforced Concrete (RC) frames with infill masonry walls under vertical loading through laboratory experiments and evaluate the contributions of infill masonry walls, in an attempt to examine the infill masonry wall added resistance to the bare frame under these circumstances. Preliminary results of laboratory tests that have been conducted on reinforced concrete infilled frames without a support at their end, under monotonic vertical loading along that column axis will be presented. The observed damages and failure modes under vertical loading are clearly different from the already known failure modes observed in the case of lateral loading.

Numerical Simulation of Ring-Shape Rock Failure under Compressive Loading

2011 ◽  
Vol 378-379 ◽  
pp. 15-18
Author(s):  
Yong Bin Zhang ◽  
Zheng Zhao Liang ◽  
Shi Bin Tang ◽  
Jing Hui Jia
Keyword(s):  
Numerical Simulation ◽  
Fracture Process ◽  
Failure Modes ◽  
Failure Process ◽  
Compressive Loading ◽  
Orientation Angle ◽  
Crack Orientation ◽  
Ring Specimen ◽  
Ring Shape ◽  
Good Agreement

In this paper, a ring shaped numerical specimen is used to studying the failure process in brittle materials. The ring specimen is subjected to a compressive diametral load and contains two angled central cracks. Numerical modeling in this study is performed. It is shown that the obtained numerical results are in a very good agreement with the experiments. Effect of the crack orientation angle on the failure modes and loading-displace responses is discussed. In the range of 0°~40°, the fracture paths are curvilinear forms starting from the tip of pre-existing cracks and grow towards the loading points. For the crack orientation angle 90°, vertical fractures will split the specimen and the horizontal cracks do not influence the fracture process.

Crack Propagation and Local Failure Simulation of Reinforced Concrete Subjected to Projectile Impact Using RBSM

2016 ◽  
Author(s):  
Yoshihito Yamamoto ◽  
Soichiro Okazaki ◽  
Hikaru Nakamura ◽  
Masuhiro Beppu ◽  
Taiki Shibata
Keyword(s):  
Reinforced Concrete ◽  
Crack Propagation ◽  
High Velocity ◽  
Failure Modes ◽  
Concrete Structures ◽  
Constitutive Models ◽  
Local Failure ◽  
High Velocity Impact ◽  
Velocity Impact ◽  
Projectile Impact

In this paper, numerical simulations of reinforced mortar beams subjected to projectile impact are conducted by using the proposed 3-D Rigid-Body-Spring Model (RBSM) in order to investigate mechanisms of crack propagation and scabbing mode of concrete members under high-velocity impact. The RBSM is one of the discrete-type numerical methods, which represents a continuum material as an assemblage of rigid particle interconnected by springs. The RBSM have advantages in modeling localized and oriented phenomena, such as cracking, its propagation, frictional slip and so on, in concrete structures. The authors have already developed constitutive models for the 3D RBSM with random geometry generated Voronoi diagram in order to quantitatively evaluate the mechanical responses of concrete including softening and localization fractures, and have shown that the model can simulate cracking and various failure modes of reinforced concrete structures. In the target tests, projectile velocity is set 200m/s. The reinforced mortar beams with or without the shear reinforcing steel plates were used to investigate the effects of shear reinforcement on the crack propagation and the local failure modes. By comparing the numerical results with the test results, it is confirmed that the proposed model can reproduce well the crack propagation and the local failure behaviors. In addition, effects of the reinforcing plates on the stress wave and the crack propagation behaviors are discussed from the observation of the numerical simulation results. As a result, it was found that scabbing of reinforced mortar beams subjected to high velocity impact which is in the range of the tests is caused by mainly shear deformation of a beam.

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