scholarly journals Numerical Study of Damage Modes and Damage Assessment of CFST Columns under Blast Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Junhao Zhang ◽  
Shiyong Jiang ◽  
Bin Chen ◽  
Chunhai Li ◽  
Hao Qin
Keyword(s):  
Numerical Study ◽  
Load Capacity ◽  
Progressive Collapse ◽  
Blast Loading ◽  
Steel Tube ◽  
Critical Parameters ◽  
Blast Loads ◽  
Finite Element Program ◽  
Damage Degree ◽  
Cfst Columns

Columns of frame structures are the key load-bearing components and the exterior columns are susceptible to attack in terrorist blasts. When subjected to blast loads, the columns would suffer a loss of bearing capacity to a certain extent due to the damage imparted, which may induce the collapse of them and even cause the progressive collapse of the whole structure. In this paper, the high-fidelity physics-based finite element program LS-DYNA was utilized to investigate the dynamic behavior and damage characteristics of the widely used concrete-filled steel tube (CFST) columns subjected to blast loads. The established numerical model was calibrated with test data in open literatures. Possible damage modes of CFST columns under blast loading were analyzed, and the damage criterion based on the residual axial load capacity of the columns was adopted to assess the damage degree. A parametric study was conducted to investigate the effects of critical parameters such as blast conditions and column details on the damage degree of CFST columns. Based on the numerical simulation data, an empirical equation was proposed to estimate the variation of columns damage degree with the various parameters.

The Dynamic Responses of RC Columns Subjected to Blast Loading

2011 ◽  
Vol 105-107 ◽  
pp. 784-790
Author(s):  
Zhi Ping Kuang ◽  
Lei Xie ◽  
Qiu Hua Yang ◽  
Yi Ling Dong
Keyword(s):  
Progressive Collapse ◽  
Blast Loading ◽  
Dynamic Responses ◽  
Blast Loads ◽  
Rc Columns ◽  
Dangerous Situation ◽  
Blast Resistant Design

The blast-resistant performance of columns which are the most important component in the whole structure is a crucial factor which influences the safety of the structures subjected to the blast loads. Studying dynamic responses of RC columns under the blast loading and improving the blast-resistant performance can prevent the structure from progressive collapse due to the damage of the columns in the blast loading, and give people more time to escape from the building in a dangerous situation. Then the same parameters are used to analyze the dynamic responses of RC columns under three typical blast loads. Conclusion can be used for structure blast-resistant design.

Behavior of New Type of Semi-Rigid Joints under Moment and Tensional Force

2012 ◽  
Vol 226-228 ◽  
pp. 1165-1169
Author(s):  
Man Xu ◽  
Shan Gao ◽  
Yu Yin Wang
Keyword(s):  
Progressive Collapse ◽  
Bending Moment ◽  
Steel Tube ◽  
Load Path ◽  
Catenary Action ◽  
Rigid Connection ◽  
New Type ◽  
Cfst Columns ◽  
The Moment ◽  
Rigid Joints

In the system of preventing progressive collapse, the joints always play a key role in catenary action and alternate load path while the joints are usually under the combination of bending moment and tensional force. In this combination, high rotation capacity and good resistance of joints are demanded. In this paper, a new type of semi-rigid joint used in the structures with concrete-filled square steel tube (CFST) columns is proposed and developed by ABAQUS. The new type joint is suitable for the classification for semi-rigid connection; The bending moment resistance of the joint decreases linearly with the increase of tensional force; reducing pretension force reasonably is beneficial for the tensional force to develop “catenary action”; the width of short leg of angle would influence the moment resistance of the joint evidently; the initial rotation stiffness is not affected by width of leg dramatically.

scholarly journals Practical Hybrid Machine Learning Approach for Estimation of Ultimate Load of Elliptical Concrete-Filled Steel Tubular Columns under Axial Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-19 ◽  
Author(s):  
Tien-Thinh Le
Keyword(s):  
Machine Learning ◽  
Load Capacity ◽  
Axial Loading ◽  
Steel Tube ◽  
Coefficient Of Determination ◽  
Inference System ◽  
Elliptical Cross ◽  
Real Coded Genetic Algorithm ◽  
Hybrid Machine ◽  
Cfst Columns

In this study, a hybrid machine learning (ML) technique was proposed to predict the bearing capacity of elliptical CFST columns under axial load. The proposed model was Adaptive Neurofuzzy Inference System (ANFIS) combined with Real Coded Genetic Algorithm (RCGA), denoted as RCGA-ANFIS. The evaluation of the model was performed using the coefficient of determination (R2) and root mean square error (RMSE). The results showed that the RCGA-ANFIS (R2 = 0.974) was more reliable and effective than conventional gradient descent (GD) technique (R2 = 0.952). The accuracy of the present work was found superior to the results published in the literature (R2 = 0.776 or 0.768) when predicting the load capacity of elliptical CFST columns. Finally, sensitivity analysis showed that the thickness of the steel tube and the minor axis length of the elliptical cross section were the most influential parameters. For practical application, a Graphical User Interface (GUI) was developed in MATLAB for researchers and engineers and to support the teaching and interpretation of the axial behavior of CFST columns.

scholarly journals Effect of MS Rings’ Confinement on Lateral Deformations of M 25 Grade Circular RCC Columns under Axial Compression Loads

2020 ◽  
Vol 9 (5) ◽  
pp. 221-223
Keyword(s):  
Mild Steel ◽  
Axial Compression ◽  
Experimental Work ◽  
Load Capacity ◽  
Compressive Load ◽  
Steel Tube ◽  
Lateral Deformation ◽  
Steel Pipes ◽  
Long Time ◽  
Cfst Columns

Confinement has been always a key concern area for researchers in present and in past also. The metal confinement of RCC columns has been extensively used from long time like concrete-filled steel tube (CFST) columns etc. In the present work mild steel rings have been used as confining material. In this paper based on experimental work, it is aimed to improve the axial compression strength and lateral deformation characteristics of circular RCC columns confined by mild steel (MS) rings. Total 45 nos. of specimen of size 150 mm dia. and 300 mm height were prepared during the experimental work. These specimen were tested and results were analyzed.These MS rings confined circular RCC columns of M 25 grade concrete were experimentally studied for different variables like (i) % of column main vertical steel bars (ii) thickness of MS rings (iii) spacing of MS rings. It was found that the MS ring confinement effectively helped in reducing lateral deformation of circular RCC column specimen resulting in improved axial compressive load capacity of circular RCC columns also. As MS rings are made up of conventional material i.e. mild steel pipes, the technique has a vast application area. In rural part of India this technique can be conviniently used for the efficient confinement of RCC columns.

scholarly journals Axial behaviour of concrete filled steel tube stub columns: a review

2018 ◽  
Author(s):  
Soner Güler ◽  
Fuat Korkut ◽  
Namik Yaltay ◽  
Demet Yavuz
Keyword(s):  
Cross Section ◽  
Axial Load ◽  
Load Capacity ◽  
Local Buckling ◽  
Bending Moment ◽  
Steel Tube ◽  
High Rise ◽  
Axial Load Capacity ◽  
The Cross ◽  
Cfst Columns

Concrete-filled steel tubular (CFST) columns are widely used in construction of high-rise buildings and peers of bridges to increase the lateral stiffness of the buildings, the axial load capacity, ductility, toughness, and resistance of corrosion of the columns. The CFST columns have much superior characteristics compared with traditionally reinforced concrete columns. The position of the concrete and steel tube in the cross-section of the CFST column is the most appropriate solution in terms of the strength and ductility. The steel tube, which is placed outside of the cross-section of the column, withstand the bending moment effectively. The concrete that is placed into the steel tube delay the local buckling of the steel tube and increase the axial load capacity of the column due to continually lateral confining. This paper presents a review on experimental results of the axial behavior of CFST columns performed by various researchers.

NUMERICAL STUDY OF BLAST-RESISTANT SANDWICH PANELS WITH ROTATIONAL FRICTION DAMPERS

2013 ◽  
Vol 13 (06) ◽  
pp. 1350014 ◽  
Author(s):  
WENSU CHEN ◽  
HONG HAO
Keyword(s):  
Energy Absorption ◽  
Sandwich Panel ◽  
Numerical Study ◽  
Blast Resistance ◽  
Sandwich Panels ◽  
Blast Loading ◽  
Blast Loads ◽  
Friction Damper ◽  
Energy Absorber ◽  
Blast Energy

Blast-resistant structures are traditionally designed with solid materials of huge weight to resist blast loads. This not only increases the construction costs, but also undermines the operational performance. To overcome these problems, many researchers develop new designs with either new materials or new structural forms, or both to resist the blast loads. Friction damper, as a passive energy absorber, has been used in earthquake-resistant design to absorb vibration energy from cyclic loading. The use of friction damper in blast-resistant design to absorb high-rate impact and blast energy, however, has not been well explored. This study introduces a new sandwich panel equipped with rotational friction hinge device with spring (RFHDS) between the outer and inner plates to resist the blast loading. This device RFHDS, as a special sandwich core and energy absorber, consists of rotational friction hinge device (RFHD) and spring. The RFHD is used to absorb blast energy while the spring is used to restore the original shape of the panel. This paper studies the mechanism of RFHD by using theoretical derivation and numerical simulations to derive its equivalent force–displacement relation and study its energy absorption capacity. In addition, the energy absorption and blast loading resistance capacities of the sandwich panel equipped with RFHDS are numerically investigated by using Ls-Dyna. It is found that the proposed sandwich panel can recover, at least partially its original configuration after the loading and thus maintain its operational and blast-resistance capability after a blasting event. In order to maximize the performance of the proposed sandwich panel, parametric calculations are carried out to study the performance of RFHDS and the sandwich panels with RFHDS. The best performing sandwich panel with RFHDS in resisting blast loadings is identified. This sandwich panel configuration might be employed to mitigate blast loading effects in structural sandwich panel design.

scholarly journals Effect of blast loading and resulting progressive failure of a cable-stayed bridge

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Ravi Mudragada ◽  
S. S. Mishra
Keyword(s):  
Progressive Failure ◽  
Blast Resistance ◽  
Progressive Collapse ◽  
Building Structures ◽  
Structural Elements ◽  
Blast Loads ◽  
Cable Stayed Bridge ◽  
Bridge Performance ◽  
Cable Stayed Bridges

AbstractMany researchers have carried out experimental and numerical investigations to examine building structures’ response to explosive loads. Studies of bridges subjected to blast loads are limited. Hence, in this study, we present a case study on a cable-stayed bridge, namely, Charles River Cable-Stayed Bridge-Boston, to assess its robustness and resistance against the progressive collapse resulting from localized failure due to blast loads. Three different blast scenarios are considered to interpret the bridge performance to blast loads. To monitor the progressive failure mechanisms of the structural elements due to blast, pre-defined plastic hinges are assigned to the bridge deck. The results conclude that the bridge is too weak to sustain the blast loads near the tower location, and the progressive collapse is inevitable. Hence, to preserve this cable-stayed bridge from local and global failure, structural components should be more reinforced near the tower location. This case study helps the designer better understand the need for blast resistance design of cable-stayed bridges.

Experimental and numerical study of a RC member under a close-in blast loading

2016 ◽  
Vol 127 ◽  
pp. 145-158 ◽  
Author(s):  
Ramón Codina ◽  
Daniel Ambrosini ◽  
Fernanda de Borbón
Keyword(s):  
Numerical Study ◽  
Blast Loading

Mitigation strategies of underground tunnels against blast loading

2021 ◽  
pp. 204141962110380
Author(s):  
Senthil Kasilingam ◽  
Muskaan Sethi ◽  
Loizos Pelecanos ◽  
Narinder K Gupta
Keyword(s):  
Blast Loading ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Mitigation Strategies ◽  
Critical Parameters ◽  
Small Scale ◽  
Burial Depth ◽  
Inelastic Behavior ◽  
Steel Fiber Reinforced Concrete ◽  
Finite Element Software

An evaluation of mitigation strategies of underground tunnels against explosions is important to the society. Therefore, a small scale tunnel was modeled against blast loading using finite element software ABAQUS. The inelastic behavior of concrete and steel bar has been incorporated through concrete damage plasticity model and Johnson-cook models respectively, available in ABAQUS. The Drucker-Prager model as well as acoustic infinite medium have been used to model the damage behavior of soil and tunnel respectively. The simulated results thus obtained from the present study were compared with the experimental results available in the literature and found in good agreement. Further, the simulations were carried to predict the damage intensity in tunnel in terms of acceleration, impulse velocity, displacement, and Mises stresses. There are many parameters which were taken into consideration to assess the mitigation strategies for the underground tunnels. The critical parameters include the influence of tunnel shapes, lining materials, lining thickness, burial depth of the tunnels, inclusion of a barrier in between the blast source-the tunnel and layered configuration of tunnel lining, and were considered to evaluate the mitigation strategy. It was concluded that the square shape of tunnel was most vulnerable as compared to circular and U-shaped tunnels. It was also concluded that plain concrete monolithic lining as well as layered configuration consisting of Dytherm foam layer between Steel Fiber reinforced Concrete layers, was found to be more vulnerable among the chosen lining materials. Also, the thickness of lining and burial depth of the tunnel found to be a significant role against blast loading.

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