to study and analysis of rcc structure under blast …

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Abstract— A bomb explosion within or immediately nearby a building can cause catastrophic damage on the building's external and

internal structural frames, collapsing of walls, blowing out of large expanses of windows, and shutting down of critical life-safety systems.

In addition, major catastrophes resulting from gas-chemical explosions result in large dynamic loads, greater than the original design

loads, of many structures. Studies were conducted on the behaviour of structural concrete subjected to blast loads. This analysis

investigates the behaviour of reinforced concrete blast wall subjected to air blast loading. A total of four different charge weight of TNT,

which represents a minimum loading capacity of person or vehicle to carry an explosive was simulated at a stand-off distance of 1.7 m and

2 m from the blast wall.

Comparison of analysis results such as deflection and stress, the blast wall wrapped with GFRP showed better performance

in preventing damages due to explosion. The degree of resistance to explosion of GFRP wrapped blast wall is greater in higher TNT

values.

.

Key Words- explosive, GFRP material, concrete structure, CREO ansys.

1. INTRODUCTION

Some structures, both military and civilian, might experience explosive loads during their service life. Owing to high

uncertainties in blast load predictions and structural parameters, accurate assessment of the performances of structures under

explosion loads is a challenging task. Reinforced concrete is the principal material for military engineering and nuclear power plant

containment. However, impacts and explosions could completely destroy such structures, causing tremendous casualties and

property loss. In recent years due to different accidental or intentional, blast all over the world resulted in studies of the resistance of

structures to blast and to develop system to reduce the hazards. The behaviour of structures components subjected to blast loading

has been the subject of considerable research effort in recent years. Blast wall is known as barrier wall used to isolate buildings or

areas from material containing, highly combustible or explosive materials or to protect a building or an area from blast damage

when exposed to explosions. Reinforced concrete blast wall is the type used for blast wall protection.

Since from few years, structures which are subjected to blast loading have got importance hence these are taken into

consideration for design. Commonly in conventional building blast load is not considered in design because the magnitude of effect

is high, it leads towards uneconomical in both design and construction. Due to blast, the buildings are liable to damage. Due to

recent past blast attacks in the country trigger the minds of developers, architects and engineers to find the solution to overcome the

blast effects and to avoid the disasters of the buildings.

1.1 PROBLEM STATEMENT

Most buildings are commonly designed for conventional loads. Explosions costs catastrophic damage and the trauma to society

can be severe. There is also an increase of threats to structures and terrorists activities due to political and social instabilities in

many different parts of the world. An effective security system may reduce to potential threat of an attack, but it will never entirely

eliminate its occurrence. Commercial buildings are built quite differently compare to military structures and are vulnerable to blast

and ballistic effects. On the other hand, one of the main challenges associated with blast loading is that the information related to

blast phenomenon is scattered in many different sources. What is more, certain information in the field of blast effects remains

TO STUDY AND ANALYSIS OF RCC

STRUCTURE UNDER BLAST LOADING

M. J. Sonavane1, Prof. G. H. Kumbhar2, Prof. M. N. Shirsath3.

M. E. structural engineering, G. H. raisoni college of Engg. & management, Ahmednagar,

JASC: Journal of Applied Science and Computations

Volume VI, Issue VI, JUNE/2019

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classified and cannot be accessed by all engineers.

Design consideration against explosion is very important in high-rise facilities such as public and commercial

tall buildings. Therefore, it is important to gather the available literature review on explosives, blast phenomena, blast wave

interaction and response of structures to blast loads.

AIM: to study the comparative analysis behaviour of the wall with and without GFRP material under the blasting condition and

to study blast effects on stresses of the wall.

1.4 OBJECTIVES

Understand the concept of behaviour of structures on blasting and its impact

Simulate Finite Element Analysis to evaluate behaviour of structures on blasting

Study optimum design, ultimate impact load capacity under blast loads

To design and analyse the building wall structure with GFRP and without GFRP material.

2. LITERATURE REVIEW

T. P. Nguyen Et. al. 2011[1], this paper studies the dynamic response of vertical wall structures under blast loading. Blast loading

is simulated by the form of dynamic excitation in time based on some assumptions to assure physical nature of dynamic problems.

The vertical wall structure is modelled by plates restrained in an edge and fixed in four edges is surveyed both linear and nonlinear

response under explosion. The nonlinear dynamic analysis is considered with cracked behaviour of the plate. The governing

equation of motion of the structure is established by Finite Element Method with quadrilateral 4 nodes elements and integrated by

constant acceleration method of New-mark’s family. BLASTSHELL program which analysed the behaviour of shell under blast

loading is built on MATLAB software.

The problem of vertical wall structures with various boundary conditions due to blast loading simulated by negative

exponential function and elasto-plastic model of material has been analysed. The BLASTSHELL program is helpful for the needs of

design work. The results show that the effect of location of explosive as stand-off distance, high and volume of TNT is sensitive to

dynamic responses of wall structures.

Xingguo Wang Et. al. 2011[2], The influence of lateral impact loading rate, longitudinal reinforcement ratio and stirrup ratio on

the failure mode, lateral load bearing capacity etc. was investigated. It was carried out with experimental research on the dynamic

response of RC columns under lateral impact loading. Results show that increasing in longitudinal reinforcement ratio can enhance

ultimate load bearing capacity of columns. The greater the loading rate, the greater the increased amplitude. It is also demonstrated

that he main influence factor on the failure mode of RC columns is stirrup spacing. The column is prone to shear failure when the

stirrup spacing is large otherwise to flexural failure.

The stirrup ratio is the main factor affecting the failure mode of frame column. The longitudinal reinforcement ratio

and loading velocity do not exert significant influence on it. If the stirrup space is large, the column will be prone to shear failure,

otherwise to flexural failure. It is important for building safety in civil engineering. The ultimate load, lateral displacement at mid-

span, extra axial force and end moment will increase with the longitudinal reinforcement. Especially, the large loading velocity

corresponds to the large increasing amplitude, with the maximum 24.7%. The transverse reactive force will also increase with the

reinforcement ratio, but the increase will be narrowed with the increase of reinforcement ratio.

Yan Liu, Et. al. 2018[3], In this study, the blast performance of steel reinforced concrete (RC) beams was experimentally and

analytically investigated. The experiment consists of a total of 10 one-half-scale beams subjected to different levels of blast loading

using live explosives. The reflected pressure-time histories were recorded and different damage levels and modes were observed.

The blast resilience of the damaged beams was quantified by measuring the time-dependent displacements. Experiment results show

that the damage in steel reinforced concrete beams with higher explosive mass is enhanced compared with that of the beams with

smaller explosive mass at the same scaled distance.

In this paper, several field tests were performed to investigate the blast response of RC beams. During the experiment, the

influence of scaled distance and charge mass on RC beams is also studied under different scaled distance and charge mass. The

experiment result shows that RC beams only suffer flexural deformation. With the decrease of the scaled distance, damage mode

changes from a few cracks on the surface to spallation on the back surface. Also, crushing on the top surface occurred. Besides, RC

beams suffer more with the increase of charge mass under the same scaled distance.



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Zeynep Koccaz, Et. al. 2018[4], The objective of this study is to shed light on blast resistant building design theories, the

enhancement of building security against the effects of explosives in both architectural and structural design process and the design

techniques that should be carried out. Firstly, explosives and explosion types have been explained briefly. In addition, the general

aspects of explosion process have been presented to clarify the effects of explosives on buildings. To have a better understanding of

explosives and characteristics of explosions will enable us to make blast resistant building design much more efficiently. Essential

techniques for increasing the capacity of a building to provide protection against explosive effects is discussed both with an

architectural and structural approach.

The aim in blast resistant building design is to prevent the overall collapse of the building and fatal damages. Despite

the fact that, the magnitude of the explosion and the loads caused by it cannot be anticipated perfectly, the most possible scenarios

will let to find the necessary engineering and architectural solutions for it. In the design process it is vital to determine the potential

danger and the extent of this danger. Most importantly human safety should be provided. Moreover, to achieve functional continuity

after an explosion, architectural and structural factors should be taken into account in the design process, and an optimum building

plan should be put together.

Ashish Kumar Tiwari, Et. al. 2018[5], this paper presents a comprehensive study of concrete wall against this dynamic loading.

Concrete wall subjected to blast loading is modeled in Finite Element package Ansys and then analysed in Autodyne with and

without steel plate to study the impact of blast loading.

It is observed from literature survey that for the estimation of blast load or pressure the empirical approach (Kinney

and Graham’s) proves to be ideal as blast phenomenon is complex in nature. Complexity arises due to unpredictability of charge

weight and standoff distance, the behavior of material under different loading conditions and post blast triggering events. Ansys

Autodyn is an efficient and user friendly tool for simulating explosives and impact loading linking it with workbench environment.

The blast simulation was carried out using JWL as equation of state for explosive materials. The concrete walls of different shapes

with or without steel plates

James P. Manthey, Et. al. 2018[6], This paper discusses the performance of 12 inch Reinforced concrete walls and provides

charts and figures which demonstrate the blast resistant capacity of such walls in several common configurations.

It is clear that when an existing 12 inch wall is being considered for a new operational function requiring personnel

protection, a detailed analysis should be provided to assure its performance.

Akhila Ramanujan, Et. al. 2018[7], bomb explosion within or immediately nearby a building can cause catastrophic damage on

the building's external and internal structural frames, collapsing of walls, blowing out of large expanses of windows, and shutting

down of critical life-safety systems. In addition, major catastrophes resulting from gas-chemical explosions result in large dynamic

loads, greater than the original design loads, of many structures. Studies were conducted on the behaviour of structural concrete

subjected to blast loads. This analysis investigates the behaviour of reinforced concrete blast wall subjected to air blast loading.

From the comparison of analysis results such as deflection and stress, the blast wall wrapped with GFRP

showed better performance in preventing damages due to explosion. The degree of resistance to explosion of GFRP wrapped blast

wall is greater in higher TNT values. Hence the GFRP panels can be recommended for various blast resistance.

C. M. Deshmukh, Et. al. 2016[8], in the present study, the RCC frame was analyzed by using conventional code for gravity loads

using moment resisting frame. The blast load was calculated using UFC-340-02 (2008) or IS 4991-1968 for 500 kg and 100 Kg

TNT at standoff distance of 10m and 30m from face of column at first floor level. The triangular impulse was applied as nodal time

history at all front face joints. The analysis was performed using Computer aided software. The response of structure of will be

evaluated under various blast scenarios. The response will be checked for safety of the structure on many parameters like

displacement, acceleration and velocity.

Blast load varies with time and distance. The behavior of structure greatly depends on charge of explosive and

its standoff distance. Due to sudden released explosive energy causes failure of structure such as collapse the structure, damage of

structural elements and crack formation in structure.

M. Meghanadh,, Et. al. 2016[9], this paper presents effect of blast loads on 5 storey R.C.C building. Effect of 100kg Tri nitro

toluene (TNT) blast source which is at 40m away from the building is considered for analysis and designed. Blast loads are

calculated manually as per IS: 4991-1968 and force time history analysis is performed in STAAD Pro. The influence of blast loads



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on structure is compared to that of same structure in static condition, The parameters like peak displacements, velocity, acceleration

are studied.

Blast resistant design refers to improving structural integrity of structure instead of complete collapse of building

,The present study on G+5 Residential building proves that Increase in stiffness of structural members by increasing in size proving

better results which also resist the uplift force on footings by increasing in dead weights.

Sajal Verma., Et. al. 2015[10], The Indian code does not have enough provisions for dealing with blast load, so it is important to

study the properties of blast loading as dynamic loading. The various methods discussed are FRP retrofit technique in masonry

walls, unidirectional passive dampers in steel structures, varying core density in sandwich structures and composites materials. it is

observed that FRP retrofit technique in blast protection and steel structure with passive dampers are effective as blast resistance

technique since no visible damage, crack, or de-bonding occurred in any of the walls and steel structure as the internal energy is

mainly dissipated by the dampers.

Blast loading and blast resistance techniques used in structures are discussed in this paper. The important

parameters of blast loadings like Strain Rate Effect, Natural Period, and Dynamic Load Factor of Vibration were studied. Different

blast resistant techniques used in masonry, concrete and steel structures were studied and following conclusions can be drawn from

the studies: FRP used in masonry walls were found to be effective in resisting blast, polyuria and GFRP retrofits were found to be

successful in preventing wall fragmentation, polyuria sprays has the capability of channelizing the load to the frame.

Mr. Chandrashekhar., Et. al. 2017[11] the effect of blast load on building is a serious matter that should be taken into

consideration in the design, Even though designing the structure to be fully blast resistant is not a realistic and economical option.

We can even improve the new and existing building to ease the effect of a blast. In this study we have analysed the effects caused

by the blast loads and to find ways to reduce the effects using Etab-2013 software. From these studies we conclude that the variation

could be analysed on unsymmetrical structures.

By increasing column and beam size in a structure will improve the resistance but it is not practical

in most cases due to serviceability problems because huge cross section of beam and column needed to resist blast loads. Addition

of shear wall and bracing helps to resist the blast loads effectively. The addition of steel bracings gives good results but shear wall

more desirable results than steel bracings and it is economical too compared to other methods.

Sana N. Kazi,, Et. al. 2017[12]. This paper presents the study of effect of Blast loading on a six storey RCC building. Effect of

variable blast source weight is calculated by considering 30 m distance from point of explosion. The blast load was analytically

determined as a pressure-time history and numerical model of the structure was created in SAP2000.The influence of the lateral

load response due to blast in terms of peak deflections, velocity, accelerations, inter storey drift is calculated and compared.

It was necessary to analyse the loading for each point. Deformation history of particular points of interest was

calculated. It is shown that the effects of blast loading can be taken into account for structural design by the use of available

literature. Available commercial software for structural analysis can be used for design purposes, while further analysis should be

directed towards familiarizing the phenomenon of the internal explosion. Thus, a complete picture of the explosion effects on the

structure can be obtained.

Ashalekshmi K G., Et. al. 2018[13]. The analysis and design of structures subjected to blast loads requires a detailed

understanding of blast phenomena, precise estimation of blast loads and the dynamic response of various structural elements. In this

thesis work, it is decided to conduct a study on explosive loading on RCC structures. Ground blast loading on an RCC bridge pier is

considered for this study. The mechanisms of various blast waves are explained. The effects of change in stand-off distance of blast,

change in grade of steel, diameter of main bars, change in diameter and spacing of lateral ties etc. are the parameters to be studied.

The thesis is mainly aimed at generalizing the effect of ground blast loading on structures and proposing a load factor for buildings

subjected to ground blast. This is a review paper prepared as a part of the thesis work.

ANSYS software is selected for the modelling and analytical purposes. Ground blast loading is applied on the pier.

Direct shock effects along with ground shock effects are considered in the loading. As the loading get closer to the structure, the

effect of temperature is more pronounced. But in this study, temperature and debris drag effect are neglected.

Michael H. Klaus, Et. al. 2018 [14]. This result and theoretical considerations lead to the conclusion that using implicit

integration is probably the best way to compute response behaviour which includes derivatives of displacements and which is due to

loading with high frequency content. As a second step, the response using a simple uniform loading according to handbook methods



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was compared with that from a hydrocode calculation. The influence of the deferent loadings on the response parameters is

considerable. The importance of a proper loading turns out to be essential for accurate acceleration results.

For response computations, which include higher derivatives of displacements and which are due to blast loading, the

implicit direct integration method with consistent mass matrix and a proper time step is superior to the explicit method and modal

analysis. This is basically due to considerations about computer costs, CPU time, and actual physical modelling.

Quazi Kashif., Et. al. 2018 [15]. This paper presents the study of effect of Blast loading on a five storey RCC building. Effect of

variable blast source weight is calculated by considering 30 m distance from point of explosion. The blast load was analytically

determined as a pressure-time history and numerical model of the structure was created in SAP2000.The influence of the lateral

load response due to blast in terms of peak deflections, velocity, accelerations, inter storey drift is calculated and compared.

In present study a five storey R.C.C symmetric building was analyzed for blast load for 100 kg and 500 kg of TNT

placed at 30 m distance from point of explosion. Blast load in each case is calculated from IS 4991-1968 and non-linear direct

integration time history analysis is carried out on Finite element software SAP-2000.

Mir M. Ali., Et. al. 2002 [16]. Several issues related to the design of concrete structures to survive blast loads are discussed in this

paper. General design issues of “terrorist proof’ buildings show how the threat of harmful blasts is affecting the thought process in

designing government and public buildings as well as international and high-visibility organizations. Understanding the loads

produced by explosions is an integral part of dealing with blast-resistant design. Case studies of buildings subjected to blasts reveal

how actual structures have handled the dynamic loads. Current research on the subject is also reviewed.

This paper has reviewed the design concepts and process for blast-resistant design of concrete

structures. For the design process of concrete members to resist blast loads, the formulas used are similar to those in the ACI code

for strength design. In addition, limit-state analysis and design should be performed to ensure that connections perform as desired.

One of the most important things to strive for is a ductile design and allowing for redundancy similar to earthquake-resistant design,

a fact that should be recognized and explored by designers of new structures under blast loading.

3 . METHODOLOGY OF THE PROJECT

This chapter deals with the methodology, the methodology is as explained under in the form of flow chart.

Analysis of project without GFRP Material

Case 1: Blast of 100 kg explosive with standoff distance of 100 m

Case 2: Blast of 100kg explosive with standoff distance of 50 m


Analysis of project with GFRP Material


Case 2: Blast of 100kg explosive with standoff distance of 50 m




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3.1 FLOWCHART

3.2 Design data collection

The data required for the project is collected from the internet mostly for this project, the required data is

Some of the above data collected from the research paper given in literature review above and other data has to be calculated by

considering height of building. The types of interlocking blocks studied on the internet and research paper will select the modified

design and will make a design structure in the CREO software.

3.3 Modelling of project

In this chapter, the general description of how the finite element model is built is noted, and the calibration of the generated Finite

Element Analysis (FEA) model is introduced. Finite element analysis proposes substantial benefits in accurateness over alternative

methods of analysis such as grillage analysis or analytical methods in many specific types of structures. (O'Brien 1999, p. 185) For

instance, FEA enables membrane forces to be modelled accurately in structures such as arch, box girder, folded plate or shell

structures. In addition, FEA modelling allows greater analytical flexibility enabling the model to be manipulated by material

characteristics, which can allow further study.

3.4 Modelling Method

Measuring displacement from the live load test can be utilized in understanding the structure displacement behaviour. In addition,

it can also become a good developmental tool of the accurate finite element model of the normal brick/ conventional brick structure.

In performing a comparison of in-field measured data and calculated data by a finite element analysis program, it is essential that

the created finite element model represents the identical displacement response as the actual behaviour.



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ANALYSIS OF STRUCTURE

1. Without GFRP material

2. With GFRP material

3. Without GFRP material

Modeling Of structure


Meshing

Deformation analysis



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Stress analysis


modelling


stress analysis



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stress analysis

With GFRP material




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Meshing of a model

modelling


stress analysis

3. Case 1: Blast of 100 kg explosive with standoff distance of 50 m

modelling



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stress analysis

4. Case 1: Blast of 100 kg explosive with standoff distance of 100 m

modelling




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stress analysis

4.RESULT

Structure without GFRP material

Displacement & stress

Sr.

no.

25 meter values

(mm)

50 meter

displacement

values (mm)

100 meter

displacement

values (mm)

displac

ement

stress displa

cemen

t

stress displa

cemen

t

stres

s

1) 93.15 835.82 87.68 705.88 90.124 652.0

2

Structure with GFRP material

Sr.

no.

25 meter values

(mm)

50 meter

displacement

values (mm)

100 meter

displacement

values (mm)

displac

ement

stress displa

cemen

t

stress displa

cemen

t

stres

s

2) 86.371 623.5

5

87.629 653.2

9

80.725 600.

07



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Graphical analysis of results

Structure without GFRP material and with GFRP material (displacement)

Structure without GFRP material and with GFRP material (stress)

5. CONCLUSION

The deflection behavior and stress of structure with and without GFRP material are analyzed using ANSYS explicit software under

explosive loading was studied using explicit analysis. It was observed that the deflection of structure and stress appears on it are

efficient in with GFRP. material as compared to the without GFRP material structure.

6. REFERENCES

1. T. P. Nguyen, Response Of Vertical Wall Structures Under Blast Loading By Dynamic Analysis, Procedia Engineering 14 (2011)

3308–3316.

2. M D goel, collapse behaviours of RCC building under blast load, Procedia Engineering 173 (2017) 1943 – 1950.

3. Yaseer Ibrahim, response of reinforced concrete frame structure under blast loading, Procedia Engineering 171 ( 2017 ) 890 –

898.



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4. Xingguo Wang, Experimental Investigation on the Effect of Reinforcement Ratio to Capacity of RC Column to Resist Lateral

Impact Loading, Systems Engineering Procedia 1 (2011) 35–41

5. Yan Liu, Behavior of reinforced concrete beams and columns subjected to blast loading, Defence Technology 14 (2018) 550e559

6. Zeynep Koccaz, Architectural And Structural Design For Blast Resistant Buildings, Procedia Engineering 165 (2016) 1953 –

1960.

7. Ashish Kumar Tiwari, Analysis of Concrete Wall under Blast Loading, International Journal of Computer Applications (0975 –

8887)

8. James P. Manthey, Blast Resistant Capacity Of 12 Inch Reinforced Concrete Substantial Dividing Walls In Accordance With

Tm5-1300.



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to study and analysis of rcc structure under blast …

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