scholarly journals Robustness of Reinforced Concrete Frames against Blast-Induced Progressive Collapse

Vibration ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 722-742
Author(s):  
Mattia Francioli ◽  
Francesco Petrini ◽  
Pierluigi Olmati ◽  
Franco Bontempi
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Local Level ◽  
Structural Response ◽  
Frame Structure ◽  
Blast Load ◽  
Response Analysis ◽  
Structural Element ◽  
Global Robustness

A quantitative procedure for the robustness and progressive collapse assessment of reinforced concrete (RC) frames under blast load scenarios is presented. This procedure is supported by multilevel numerical models, including nonlinear numerical analyses of the structural response of both local (i.e., response of the single structural element to the blast load) and global levels (i.e., response of the structural system to the blast-induced damage). Furthermore, the procedure is applied to a 2D RC frame structure. The novelty of the proposed procedure is that the global robustness is evaluated by the so-called “damage-presumption approach” where the considered damages are defined both in typology and extension depending on the blast scenario occurring at the local level. The dedicated local response analysis of a specified blast scenario leads to the proper definition of the so-called “blast-scenario dependent robustness curves”.

scholarly journals Rapid Retrofit of Reinforced Concrete Frames after Progressive Collapse to Increase Sustainability

2019 ◽  
Vol 11 (15) ◽  
pp. 4195 ◽  
Author(s):  
Li ◽  
Shan ◽  
Zhang ◽  
Li
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Design Method ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Frame Structure ◽  
Rc Frame ◽  
Concrete Frames ◽  
Before And After ◽  
Test Frame

A structural progressive collapse is usually a local failure, in which the damage is concentrated at beams that bridge the removal column and the column itself. In many cases, retrofitting the damaged structure is more economical and more sustainable than reconstructing the entire structure. A progressive collapse test of a 1/3 scale, four-bay by two-story reinforced concrete (RC) frame was conducted, after which the structure was retrofitted with carbon fiber reinforced polymer (CFRP) wraps and retested. The center column in the first story was removed and the frame was pushed down quasistatically under displacement control to investigate the progressive collapse performances of the retrofitted RC frame. The test results were represented systematically at different areas in terms of the resistance forces, crack developments, and local and global failure modes. Numerical models were built to verify the test frame before and after the retrofitting. A design method was proposed to retrofit an RC frame using CFRP wraps after a progressive collapse. The test frame was redesigned to improve the retrofitting and used as an example to demonstrate the rationality of the proposed retrofit design method. The results indicated that the proposed retrofitting technology rapidly restored the frame structure to its original capacity before the progressive collapse occurred, whilst consistently satisfying the priorities of being economical and sustainable.

Experimental of Inverted-T Shape Reinforced Concrete Wall Subjected to Blast Load

2021 ◽  
Vol 879 ◽  
pp. 254-262
Author(s):  
Mazlan Abu Seman ◽  
Sharifah Maszura Syed Mohsin ◽  
Ahmad Mujahid Ahmad Zaidi ◽  
Md Fuad Shah Koslan ◽  
Zainorizuan Mohd Jaini
Keyword(s):  
Reinforced Concrete ◽  
Blast Resistance ◽  
Retaining Wall ◽  
Construction Material ◽  
High Strength ◽  
Steel Reinforcement ◽  
Blast Load ◽  
Structural Element ◽  
Concrete Wall ◽  
Flexural Reinforcement

Reinforced concrete (RC) widely used as the construction material for the main structural element for many significant structures such as bridge and building because of its relatively high strength and economical. However, there still lacks research published regarding the appropriate reinforcement steel arrangement in a complete RC structure subjected to blast load. Most of the published experimental works focused on the small rectangular or square RC panel. From the record search, the approved design by professional engineers, when RC wall subjected to the possibility of blast load, both RC wall details either retaining wall or shear wall implemented. Therefore, the full-scale blast experiment is vital to appraise the appropriate steel reinforcement arrangement in the RC wall. The blast experiment indicated, with different steel reinforcement arrangement in the RC wall, the better blast resistance with the number of cracks on the RC wall is significantly less from one another for the wall with the arrangement of horizontal flexural reinforcement tied-outside the vertical flexural reinforcement and the hooked-in direction of vertical flexural steel reinforcement into the wall base.

scholarly journals Structural Response and Reliability Analysis of RC Beam Subjected to Explosive Loading

2011 ◽  
Vol 82 ◽  
pp. 434-439 ◽  
Author(s):  
Maurizio Acito ◽  
Flavio Stochino ◽  
Sergio Tattoni
Keyword(s):  
Reinforced Concrete ◽  
Reliability Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Structural Response ◽  
Blast Load ◽  
Rc Beam ◽  
Maximum Displacement ◽  
Sdof System ◽  
Flexural Member ◽  
Random Nature

The random nature of the explosion load, associated with the random nature of material properties, and geometric dimensional characteristics, implies the need to consider them into the reliability analysis in order to have a more correct estimation of the structural behavior. Therefore, when the randomness of these parameters in the analysis is considered, the response of the structure assumes probabilistic nature, and this makes it necessary to look into the reliability measure. This paper presents results from a parametric investigation of the reliability of reinforced concrete (RC) beam subjected to blast load. The probabilistic responses of the maximum displacement for a reinforced concrete flexural member under blast loadings are evaluated by means of nonlinear dynamic analysis with simplified equivalent single-degree-of-freedom (SDOF) system. Results of numerical simulations have shown the response of structures, in terms of maximum displacement in relation also to the blast load and the geometrical and mechanical characteristics of the beams. Monte Carlo simulation of dynamic response of the equivalent SDOF system is performed to estimate the reliability.

Blast Vulnerability Assessment of Road Tunnels with Reinforced Concrete Liners

2018 ◽  
Vol 2672 (41) ◽  
pp. 156-164 ◽  
Author(s):  
Fengtao Bai ◽  
Qi Guo ◽  
Kyle Root ◽  
Clay Naito ◽  
Spencer Quiel
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Transportation Network ◽  
Computational Effort ◽  
Public Access ◽  
Tunnel Current ◽  
Circular Tunnel ◽  
Inflection Points ◽  
Road Tunnels

Tunnels are a critical component of our transportation infrastructure, and unexpected damage to a tunnel can significantly and adversely impact the functionality of a transportation network. Tunnel systems are vulnerable to potential threats of intentional and accidental blast events because of their relatively unrestricted public access. These events can lead to spalling and breach of the tunnel liner which, depending on the surrounding media, can result in local damage and progressive collapse of the tunnel. Current approaches for evaluating blast-induced damage to a tunnel liner either require significant computational effort or oversimplification such that accurate spatial distributions of damage cannot be obtained. This study presents an effective approach to predict and map the damage to a reinforced concrete liner of a roadway tunnel from various explosive threat sizes and tunnel geometries. A literature review of existing studies is conducted, and potential scenarios of blast events are examined with varying charge position and size. Rectangular, horseshoe, and circular tunnel geometries, each with the same traffic throughput, are evaluated. An efficient analytical approach to determine the spatial distribution of blast-induced spall and breach damage is presented and shows good agreement with numerical models analyzed in LS-DYNA. The proposed approach is then used to examine the relationship between increasing blast hazard intensity and the extent of spall and breach damage. Inflection points in this relationship can be used to identify hazard levels at which a progressive collapse evaluation would be warranted.

New Seismic Design Specifications of Highway Bridges in Japan

1994 ◽  
Vol 10 (2) ◽  
pp. 333-356 ◽  
Author(s):  
Kazuhiko Kawashima ◽  
Kinji Hasegawa
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Response ◽  
Seismic Design ◽  
Structural Response ◽  
Highway Bridges ◽  
Lateral Force ◽  
Inertia Force ◽  
Response Analysis ◽  
Design Specifications ◽  
Recent Earthquakes

This paper presents the new seismic design specifications for highway bridges issued by the Ministry of Construction in February 1990. Revisions of the previous specifications were based on the damage characteristics of highway bridges that were developed after the recent earthquakes. The primary revised items include the seismic lateral force, evaluation of inertia force for design of substructures considering structural response, checking the bearing capacity of reinforced concrete piers for lateral load, and dynamic response analysis. Emphasis is placed on the background of the revisions introduced in the new seismic design specifications.

The influence of construction joint on the seismic behavior of reinforced concrete frame structure

2016 ◽  
Vol 20 (7) ◽  
pp. 1125-1138 ◽  
Author(s):  
Jing Yu ◽  
Xiaojun Liu ◽  
Xingwen Liang
Keyword(s):  
Reinforced Concrete ◽  
Seismic Behavior ◽  
Numerical Models ◽  
Time History ◽  
Frame Structure ◽  
Nonlinear Time History Analysis ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Construction Joint ◽  
Story Drift

A new model that can simulate the behavior of construction joint subjected to seismic forces was proposed. Nonlinear time-history analysis was carried out for reinforced concrete regular frame structures designed in different seismic intensity regions as well as with different height-to-width ratios. Two kinds of numerical models are adopted to simulate the seismic behavior of each frame, one with construction joint using the new proposed model and the other without construction joint using the conventional model. Results show that the influence of construction joint on the seismic behavior of reinforced concrete frame is strongly related to structural nonlinearity. It may increase the top displacement and the inter-story drift, change the inter-story drift distributions, and exacerbated the local reaction of key members. The influence of construction joint cannot be ignored for structures with low emergency capacity against major earthquake. Seismic design suggestions are proposed from the aspect of calculation analysis method.

Experimental and Numerical Studies on the Reinforced Concrete Frames Subjected to Blast Loads

2012 ◽  
Vol 157-158 ◽  
pp. 1173-1177
Author(s):  
Li Xiao ◽  
Wen Zhong Qu ◽  
Jian Gang Wang
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Computer Code ◽  
Economic Loss ◽  
Frame Structure ◽  
Building Structures ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Blast Response

Terrorist bombing attacks will endanger and may even destroy the target building structures, resulting in economic loss and casualties. Typical columns and floor slab systems are not designed to resist the complex blast loading. So, in recent years, the effects of blast on conventional public buildings are focused on. In this paper,a two-bay,one-story reinforced concrete frame structure which is used to model a portion of a typical reinforced concrete frame structural system is used to investigate the blast response. The experiments are conducted on two models, allowing a variation in explosives standoff and explosives charge. In each experiment,the blast pressure values are recorded and the degree of damage of the frames are studied. According to the two kinds of experiments, two numerical models are established. ALE method which considers the interaction of the explosive, the air, and the structure is applied.Structure response analyses are performed using the large deformation finite-element computer code, LS-DYNA. The numerical results are compared with the experiment results, and a good agreement is obtained. The calculating results also demonstrate that some experimental value is unreasonable.

scholarly journals Transient Response of RC Panel Protected with Slurry Infiltrated Micro Reinforced Concrete Jacket under Blast Loading

2019 ◽  
Vol 8 (2) ◽  
pp. 1196-1210
Keyword(s):  
Reinforced Concrete ◽  
Blast Resistance ◽  
Structural Response ◽  
Time History ◽  
Damage Variable ◽  
Wire Mesh ◽  
Blast Load ◽  
Terrorist Attacks ◽  
Mesh Reinforcement ◽  
Single Side

With increase in terrorist attacks, there are definite priority to protect the important infrastructure facilities against possible terrorist attacks. In order to improve blast resistance capacity of RCC panel, in present study, it was strengthened with Slurry Infiltrated Micro Reinforced Concrete (SIMRC) jacket. . The SIMRC jacket strengthened RC panel was analyzed under blast load scenario using finite element method based application, ABAQUS. The dynamic behavior of concrete and grout of SIMRC was modeled using concrete damaged plasticity model. The structural response of RC panel without any strengthening was compared with SIMRC strengthened RC panel to investigate effectiveness of SIMRC jacketing to resist blast load. Parametric study was carried out considering SIMRC jacket on single side or both side of RC panel, with different ratio of thickness of jacket to thickness of RC panel (t/D) and different percentage of wire mesh reinforcement for jacket. Simulation of various analysis results were presented in form of displacement time history, distribution of tensile/compressive damage variable explaining the pattern of failure in the RC panel, comparison of distribution of tensile damage variable on front and back jacket, compression damage variable of RC panel. It was observed that for panels with strengthening displacement and damaged areas are reduced as compared to conventional RC panel. The increase in thickness ratio (t/D), percentage of wire mesh reinforcement in jacket also contribute to increase blast resistance capacity of SIMRC Jacket. It was also observed that the jacketing on both side of RC panel is more effective in reducing the displacement and the damage is observed to be spread over the support areas. Obtained results through present study demonstrate the effective use of SIMRC jacketing as blast mitigation measure.

VERIFICATION OF THE METHOD OF APPLICATION OF THE REDUCTION COEFFICIENT IN THE CALCULATION OF MONOLITHIC REINFORCED CONCRETE SYSTEMS TO RESIST PROGRESSIVE COLLAPSE

2021 ◽  
Vol 95 (3) ◽  
pp. 68-75
Author(s):  
B. MITROVIC ◽  
Keyword(s):  
Reinforced Concrete ◽  
Computational Analysis ◽  
Progressive Collapse ◽  
Deformation Characteristic ◽  
Reduction Factor ◽  
Structural Element ◽  
Limiting State ◽  
Reduction Coefficient ◽  
The Stability

The paper presents a method of using the reduction factor to ensure the stability of monolithic reinforced concrete bearing structures to progressive collapse. Within the framework of the verification study, the correctness and validity of the developed method for the computational analysis of monolithic reinforced concrete bearing systems of buildings and structures to resist progressive collapse were proved. The reduction factor (K1) obtained and justified in the framework of the research performed is the most important deformation characteristic of the special limiting state of monolithic reinforced concrete bearing systems of buildings and structures for an emergency design situation associated with the failure of a local structural element.

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