Global journal 50

www.globaljournal.asia GJESR RESEARCH PAPER VOL. 2 [ISSUE 9] OCTOBER, 2015

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RECENT TRENDS IN BLAST RESISTANT CONSTRUCTION Rohit Maurya [1], Shubhendu Vikram Singh [2] Author [1] & [2] pursuing M.Tech (Geotechnical & Geo-environmental Engineering) from Kamla Nehru Institute of Technology, Sultanpur, UP, 228118 (Mail Id – rohitmaurya12ce@gmail.com, Mob-9897042913)

ABSTRACT As growing no. of terrorist attacks since last few years , we conclude that the effect of these attacks especially bomb blast attacks the causing loads on buildings and other important structure is become a matter to take seriously. We should take all aspects and consideration to increase the architectural and structural resistance by advanced methods of designing, advanced materials and procedure of implication.

Because of these are manmade disaster that’s why it’s exceptional cases. These blast loads are actually dynamic in nature like wind and seismic load, to measure and control. So in this study we get some of the latest trends in blast resistance construction methods, material and codal provisions.

INTRODUCTION Due to terrorist attacks, there are large amount of assets waste with fatal damage of human life. Which become social panic to be stop. Constructing structure total blast resistant is not economical and reality based. So new engineering knowledge can improves the structure to decrease the explosion effect.

NEED FOR BLAST RESISTANT STRUCTURE Blast resistant structure is nowadays are getting trendy around the world and it is also getting aware in India as it was so many attack that happened in India that could prevent in presence of blast resistant structure. There are approx.

LARGEST ATTACKS AROUND WORLD 1. Manhattan Attack

2. World Trade Centre Bombing 1993 3. The Wall Street bombing 4. 26/11 Mumbai Attack 5. The Okahlama City Bombing 6. 9/11 Attack (WTC)

RECENT TRENDS As we need to look for different aspects we have to go in the recent utilisation field of blast resistant construction around the world and different technologies which is used for these construction. These are as follows: 1. Ultra-high performance concrete and reactive powder concrete slabs 2. Blast-proof masonry wall system and assessment of coupling effects using a TDOF model 3. Blast resistance of stiffened sandwich panels with closed-cell aluminium foam 4. Impulse-resistant metal sandwich plates 5. Blast resistance of polyuria based layered composite materials 6. Polymer composites as construction materials (blast walls) 7. Innovative steel stud walls for blast resistance MATERIALS

USED CONSTRUCTION TRENDS

IN

RECENT

In every few years there’s a change in different construction strategies in architectural, structural, environmental, economical, blast resistant etc. So likewise there’s respective change in the construction materials. There are several variety of material are used in the recent construction works. Which are as follows

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the general categories of construction materials.

1. Explosion-Resistant Concrete 2. Shock-Proof Glass 3. Indestructible Plastic 4. Blast-Proof Fabric 5. Bomb-Proof Wallpaper

Figure 1- Blast resistant material

SEVERE EFFECT OF BLAST ON STRUCTURE The blast explosions damage structures in the following manner: 1. Shock and vibration can break nonstructural components (e.g., glass window) far from incident. Create fragments which can travel long distances, causing facilities damage and bodily injury.

2. Bend, break or displace load bearing panels and beams, possibly causing structural collapse.

3. Distort and possibly rupture pressure vessel, valves, and instrumentation, releasing hazardous (toxic or explosive) material into environmental.

BASIC PRINCIPLE OF BLAST EFFECT There are ways to blast happen which will differential the working of severity to effect on any construct structure. So what happen is every blast will generate blast wave that will propagate from blast point to nearby structures as we see in this figure, it will reflect from the ground in the air and collide through the building structure in a

phase

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of

Mach

stem.

Figure 2- Propagation of blast wave After that what we get by this explosive effect on structure is find the general blast wave pressure-time history, which as shown.

Figure 3- General blast wave pressure-time graph

BACKGROUND OF THE PROBLEM An explosion or bomb blasting is becoming the major issue to handle by engineering for long time. Well first we have to know about the blasting. It is a sudden release of energy and generating large amount of heat and overpressure in air. Generally in literature the blast phenomena noted as the length blasting, but is not the only cause. One and only earliest published work in this is by Hopkinson. In WWI and WWII increment of explosives as an invasion tool and for security purpose. So it is required to make structure blast resistant.

TECHNOLOGICAL

TRENDS

IN

CONSTRUCTION

There are various type technologies are came to fulfil the requirement for blast resistant and seismic resistant construction.

These technologies are follows.

1. Adobe structures 2. Limestone and sandstone structures Š Virtu and Foi. A Non-Paid Journal

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3.

4.

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Timber frame structures Light-frame structures Reinforced masonry structures Reinforced concrete structures Pre-stressed structures Steel structures

VARIOUS

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Materials These are the materials that are used in this type of construction work as follows:  Ultra High Strength Concrete (UHSC)  Reactive Powder Concrete (RPC)

DESIGN METHODS OF BLAST

Ultra High Strength Concrete

RESISTANT

Well designing of blast resistant structure date back to 1870 that determine various blast loading pressure, overpressure, timewave graphs and tables etc. After a while some year software come along to put through the effect easy analysis , measuring , calculating , simulating in different conditions respectively growing the technologies for better evaluating and designing methods by national and international authorities since 1950 to now.

Some of the methods names are described here which will used in designing.

1. Old Empirical Methods 2. Drift Controlled Blast Resistant Design Method

There has been limited use of UHSC in North America and it is developed in France 1990. This material consist of sand, cement and silica flume in dense, low w/c ratio (0.15) mix. Along with low permeability the compressive strength of 18,000 psi to 30,000 psi can be achieved and it will depends on the curing process. Ductility of the material will be improved by adding steel or fibreglass fibre 2% by volume, this will change the use of mild reinforcing steel.

Nowadays tis material patented as Ductal developed by Cafange.

ULTRA-HIGH PERFORMANCE CON-CRETE AND REACTIVE POWDER CONCRETE SLABS

[1] In this way construction method called UHPC and RPC can improve strength of the concrete and it will reduce self-weight and member size with workability improved. By this this material compressive strength improves, sometimes 150MPa to 200MPa. That type of concrete are needed where high size building and long bridge are constructed.

Also this used in the construction for blast resistant design to prevent terrorist attack and bomb blast according to (ASCE 1999, Baker 1973). In 2009 the Code has been modified of Korean building , Where in the city of Seoul high rise loaded buildings at least 50 and over from ground floor .

Nowadays with much interest of public this way of construction of blast resistant design concept has to be incorporated.

Figure 4-UHSC and Conventional Concrete To create reference blast experiments, some controlled explosions have been conducted under ideal conditions. To relate other explosions with non-ideal conditions to the reference explosions, blast scaling laws can be employed. The most widely used approach to blast wave scaling is that formulated by Hopkinson, which is commonly described as the cube-root scaling law. The scaled distance, Z, is defined using the Hopkinson-Cranz's cube root law as (ASCE 1999): Where, Z is scaling distance; R is stand-off distance from the target structure; E is total explosive thermal amount of energy; W is charge weight of equivalent TNT amount.

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The scaling distance is used for evaluation of blast wave characteristics.

BLAST-PROOF MASONRY WALL SYSTEM AND ASSESSMENT OF COUPLING EFFECTS USING A TDOF MODEL [2]

Most of the existing buildings are not designed for this type of blast loading.

Masonry wall sections normally turn out as weak elements in security studies of urban infrastructure. Fragments of building components can be a major source of hazard to occupants. Glass of windows and materials of the walls may fragment and the resulting debris may be propelled inwards at high speed. A further threat could be the loss of the building integrity.

An international consortium of small and medium enterprises (SMEs) together with two research establishments has developed a product to retrofit masonry structures with integrated window systems. A marketready product (TECDUR) was the result of the project, which was successfully completed in December 2009. This work was part-funded by the European Commission under its FP6 Research & Technical Development Programme.

The retrofit system was developed to withstand a scenario with a car bomb by increasing strength, ductility and integrity of the structure. Other research projects have also raised these three parameters to enhance a masonry wall against such an extreme loading case. To reach the properties, an elastomeric layer including textile straps integrated in fibre-reinforced wall panels (FRP) is attached onto the existing masonry wall, see Figure 5 left.

Special glazing types for the window and a good connection between the window and the wall system allow a large viewport in the masonry structure without failure of the system. Figure 5 right shows a Blast wall window pane after a shock-tube experiment.

Figure 5-Masonry blast wall

BLAST

RESISTANCE OF STIFFENED SANDWICH PANELS WITH CLOSED-CELL ALUMINIUM FOAM [3]

Foam core sandwich panels have increased the use in various field of construction, like an example for that sacrificial blast walls, side walls and in cargo containers and boxes and various military construction (Ashby et al., 2000). These panels has best performance in case of blast as light, high specific stiffness, moisture independency and corrosive resistance. (Guru Prasad and Mukherjee, 2000a and 2000b, Hanssen et al., 2002a and 2002b, Qiuet al., 2003, Xue and Hutchinson, 2003, Radford et al., 2006, Sriram et al., 2006, Nemat-Nasser et al., 2007, Bahei-El-Din and Dvorak, 2008, Tekalur et al., 2008, Karagiozova et al., 2009, Zhu et al., 2009, and Langdon et al., 2010).

Effectiveness of stiffened metal foam sandwich structures has never been investigated. (a) Stiffener configuration, (b) Foam thickness, (c) Foam density, and (d) Standoff distance on the blast response.

Stiffened sandwich foam panel geometry and material properties The panels are square in shape (2 m × 2m) with steel sheets of 10 mm thickness on each side. The back-sheet is stiffened by stiffeners of 100mm width and 10 mm thickness for all the ten stiffened configurations with same materials (steel) as that of the face- and back-sheets. Three foam thicknesses, 50 mm, 100 mm, and 150 mm, are considered.

Figure 6 shows various configurations of the unstiffened/stiffened sandwich foam

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panels The face-sheet and stiffened backsheet are made of steel considering elastic plastic and strain hardening behaviour with Young’s modulus, E = 210 GPa, Poisson’s ratio =0.3, and density = 7,800 kg/m3 (Goel et al., 2011). The static yield stress of steel in the face and back-sheets is 300 MPa. The steel face- and back-sheets along with stiffeners are modelled using elastic-plastic material model, i.e.

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core sandwich structure is available commercially under the trade name ‘‘Navtruss’’. Each of the three types of sandwich plate has a basic unit that is repetitive in the long direction (perpendicular to the plane of the crosssection in (Fig. 7b).

Figure 6- Stiffened sandwich panels IMPULSE-RESISTANT PLATES [4]

METAL

SANDWICH

Most structures designed to withstand large blast loading on solid-wall plate and shell components. The relative advantage of clamped circular sandwich plates with a tetragonal truss core is the over equal weight of solid plates subject to identical initial momentum impulses. Fluid–structure interaction quite affects the momentum to the sandwich plate relative to the solid plate of similar weight. While the effect in air is small, for blast waves transmitted in water, the momentum to a metal sandwich plate is substantially less than that imparted to the solid plate of equal mass.

Three types of sandwich cores Infinite plates of width 2L that are clamped along their edges are considered, as depicted Schematically in Fig 7a.

Three core geometries are analysed: 1. Pyramidal truss, 2. Square honeycomb, 3. Folded (or corrugated) plate.

Pyramidal truss core sandwich plates have recently been manufactured for relatively low cost applications, such as decking for transport ships. Folded plate

Figure 7a, 7b, 7c-Type of sandwich plates

BLAST

RESISTANCE OF POLYURIA BASED LAYERED COMPOSITE MATERIALS [5]

In military, naval and defence the composite material have widespread application. Due to the recent development by the researcher in polymer based coating on building and structure to increase the resistive capacity and to find the minimum amount of material required to withstand the structure safely by observing blast energy. By adding polyuria in composite material makes so much complexity due to nonlinear behaviour measuring by the structure response.

Materials E-glass vinyl ester composite (plain–woven composite) the resin system used was Dow Chemical’s Derakane 510A-40. The glass

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fabric chosen was woven roving E-glass supplied by Fibre Glass Industries’ (FGI).

The areal weight was 610 g/m2 (18 oz/sqyd) with an unbalanced construction having 59% and 41% of fibres in warp and fill directions respectively. Further details about the composite material can be found in figure.

Polyuria Polyuria is a cross-linked amorphous isocyanate monomer or pre-polymer and polyamine curative. To be classified as a polyuria, the compound must contain at least 80% polyamine. There are two basic types of polyuria: aromatic and aliphatic.

The EP JS has 20.34 MPa (2950 psi) tensile strength, 350% elongation, 11.16 MPa (1620 psi) modulus, and 87.5 kN/m (500 lb/in) tear strength.

Figure 8-Test polyuria sheets

POLYMER

COMPOSITES AS CONSTRUCTION MATERIALS (BLAST WALLS) [7]

These are the separate structural parts which will directly use in the construction as wall for protection in buildings from blast loading. These elements consist of sandwich panels, added layers or hybrid structure. The basic requirement of this blast wall is that, it will observed energy and have good resistance along buckling.

Continuous research of resins and fibre gives us full performance and also the ability to ass with other materials. It implicate as a decorative facings, linings and wall components.

Material In this type of blast resistant construction FRP blast walls are used, which is known as Fibre Reinforced Polymers.

Fibrereinforced polymer panels have advantages

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of being relatively flexible, which will act as an absorption mechanism from multi-phase blast loads. Additionally, by filling the FRP panels with native granular materials to achieve the protection, the panels receive a benefit of increased inertial resistance.

Figure 9-Polymer composites Impact of application Engineering: · The superior mechanical performance of composite or hybrid composite components means that the required level of protection can be achieved with a lower volume and weight of material.

1. Modularity of composite components for quick and easy installation of both temporary and permanent protection facilities.

2. Composite components are highly machine-able they can be drilled, screwed or cut during installation in field applications.

3. Composite panels are easy to repair in the field

BOMB BLAST RESISTANT GLAZING [8]

The first test method that developed in this area of bomb blast was ASTM F 1642, Standard Test Method for Glazing Systems Subject to Air blast Loadings, published in 1996. Through arena or shock tube testing the test method which was applied to glazing or glazing systems and provided a means of establishing the air blast resistance capacity of these materials. If an opening was created in the glazing a specimen was deemed to have failed through which air blast pressure could pass or if spall from the specimen penetrated an aluminium foil witness panel placed twelve inches behind the test specimen. The

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American Architectural Manufacturers Association published their standard AAMA 510-06 Voluntary Guide Specification for Blast Hazard Mitigation for Fenestration Systems.

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The aim of this study to spread the awareness of blast resistant building design is to prevent the overall collapse of the building and fatal damages of human life.

Despite the fact that, the exposer of the explosion and the loads caused by it cannot be bared perfectly, the most possible scenarios will let to find the necessary engineering advancement and architectural solutions for it.

ACKNOWLEDGEMENTS: Figure 10- Window, wall glazing

INNOVATIVE

STEEL STUD BLAST RESISTANCE [6]

WALLS

FOR

SEB wall is ground breaking solution for blast resistant construction. These walls consists of CFS studs sheathed (conventional) with composite steel /board plate sheathing as we know SURE BOARD. According to researcher Simpson Gumpertz and Heger by his analytical program of SEB wall, find out this has ability to resist the high blast threats vehicle.

Figure 11-SEB walls WORKING OF SEB WALLS These walls primarily comprises of CFS wall with full detailing to avoid unwanted failures modes which sheathed on both side of the wall by sheathing. This provide sufficient structural benefits in lateral bracing to improve the flexural capacity under pressure loading. By the use of strategically shear stiffeners in SEB wall developed the angle correction and track.

CONCLUSIONS:

The author acknowledge the Dr N. K Saxena Head, Department of civil engineering, Kamla Nehru Institute of Technology, Sultanpur, UP. And Prof. Anupam Verma (Asstt. Professor) providing his guidance to this work.

REFERENCES: 1. J.H.J. Kim, N.H. Yi, I.S. Oh & H.S. Lee Yonsei University, Seoul, Korea J.K. Choi & Y.G. Cho Hyundai Institute of Construction Technology, Yongin, Korea “Blast loading response of ultra-high performance concrete and reactive powder concrete slabs” 2010 Korea Concrete Institute, ISBN 978-89-5708182-2 2. Kai Fischer, Werner Riedel, Julia Ziehm “Full-scale validation of a blast-proof masonry wall system and assessment of coupling effects using a TDOF model” 14th International Symposium on Interaction of the Effects of Munitions with Structures- ISIEMS, September 19– 23, 2011 3. Manmohan Dass Goel a ,Vasant A. Matsagar b ,Anil K. Gupta “Blast Resistance of Stiffened Sandwich Panels with Closed-Cell Aluminum Foam” Latin American journal of solids and structures 11 (2014) 2497-2515 4. Zhenyu Xue, John W. Hutchinson ”A comparative study of impulse-resistant metal sandwich plates” International Journal of Impact Engineering 30 (2004) 1283–1305

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5. Srinivasan Arjun Tekalur , Arun Shukla , Kunigal Shiva Kumar “Blast resistance of polyuria based layered composite materials” Composite Structures 84 (2008) 271–281 6. Ady Aviram Ph.D., PE, Ronald L.,Mayes , Ph.D., Ronald Hamburger ,SE ,SECB “Innovative steel stud walls for blast resistance”. Building Blocks , Structure Magzine june 2014 .Pg,20-22 7. John Hoemann and Hani Salim, Robert J. Dinan, Ph.D. Air Force Research Laboratory. “Fiber reinforced polymer (FRP) panels for blast and fragmentation mitigation”. AFRL-RX-TY-TP-2008-4533 8. Block, Valerie, marketing specialist at DuPont, Wilmington, DE, USA “Bomb Blast Resistant Glazing: Testing and Standards”. www.protectiveglazing.org 9. S. C. Dutta, R. Roy, “Performance of Seismically Designed Buildings under Blast Loading”. IJST, Transactions of Civil Engineering, Vol. 36, No. C2, pp 149-166 Printed in The Islamic Republic of Iran, 2012 10. WIKIPEDIA –(Top 10 largest attack ever ) 11. UNIFIED FACILITIES CRITERIA (UFC) “DoD Minimum Antiterrorism Standards For Buildings”. UFC 4-010-01 change 1 October 2013 USA

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