Miyamoto H.K & Taylor D. - Structural Control of Dynamic Blast Loading Using Passive Energy Diss

Miyamoto H.K & Taylor D. - Structural Control of Dynamic Blast Loading Using Passive Energy Diss

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Unformatted text preview: SEAOC 1999 CONVENTION J STRUCTURAL CONTROL 51:4 DYNAMIC DLAST LOADING USING PASSIVE ENERGY DISSIPATORS ABSTRACT The purpose of this paper is to evaluate the effectiveness of Fluid Viscous Dampers (FVD) when used to control blast loading responses on lateral load resistive frames. In particular, this paper addresses the following issues: 1) Development of a blast loading time history for a 3,000 pound TNT blast; 2) Characteristics and historical applications of FVD for blast and weapon effects; and 3) Blast effects and performance comparisons of a conventional special moment resisting frame (SMRF), SMRF with F VD, and a conventional shear wall building. Nonlinear dynamic force history analyses were conducted on three different types of structures: 1) Conventional SMRF, 2) SMRF with FVD, and 3) Conventional concrete shear wall. The lateral load resisting frames of these structures were designed to conform to the 1994 Uniform Building Code, Zone 4 criteria. Nonlinear computer models with and without FVD were subjected to a dynamic blast loading from 3,000 pounds of TNT at 100, 40, and 20-foot distances. Nonlinear analyses indicated that structures with FVD provided a cost effective way to control displacement and plastic hinge rotation of lateral load resisting frames under blast loading. BLAST LOADING TIME HISTORIES FOR A 3,000 lb CHARGE OF TRINITROTOLUENE (TNT) The intent of this report is to study the relative performance of structures subjected to transient pulses caused by the detonation of explosives. Most explosives are developed and used primarily by the military and government agencies. Very little data is published in the public domain concerning blast pulse magnitudes and wave forms. The transient pulses presented here are for reference only. They were assembled entirely from an unclassified database of public domain 299 H. Kit Miyamoto, M.S., S.E. Mart Shaffer & Miyamoto, Inc. Sacramento, CA Douglas Taylor Taylor Devices, Inc. North Tonawanda, NY material, and were appropriately scaled for use. In general, the frequency content from the time history of a detonation is at least an order of magnitude higher than the structural frequencies of a conventional building. Thus, it is not necessary to utilize high precision transients. Since only conventional buildings were to be studied, the extremely short explosive pulse durations also indicated that integrated pulse content was much more important than a highly precise wave form. For these reasons, all pulses were rendered generic by reducing them to an equivalent triangular wave form. The resultant time histories provide what is essentially a pressure impulse, which is then applied to the structure (See Figures 1, 2 &3). The time histories utilized are related to the detonation of a charge roughly equivalent in yield to 3,000 lb of TNT. The charge is assumed to be placed in a suitable container, which, in turn, is placed within an enclosed vehicle such as a truck or large van. No attempt was made to account for confinement of the charge within the vehicle. It must be remembered that the failure of inducing mechanisms of a detonation include several very different components. These include: 1) Blast over-pressure, 2) Ejecta, 3) Cratering, 4)Thermal Radiation, and 5) Induced ground motion. The type of charge for the explosives, and their placement and range from the target will determine which of these components will dominate for a given event. For all cases studied here, blast over-pressure was considered to be the most significant failure causing mechanism. However, as the range is decreased, it is expected that the damage caused by ejecta (being objects and material driven from a vehicle and crater by the explosion at extremely close ranges) will become substantial. Cratering failures will eventually dominate, especially if the charge is placed in close proximity to one or more of the building columns, thus causing catastrophic failure. FLUID VISCOUS DAMPERS (FVD) FOR BLAST EFFECT The fluid damper is well known throughout the military for its ability to arrest gun recoil, and numerous other military uses began in the post World War [I era. Most were related to the protection of electronic systems on military platforms subject to attack by an enemy’s explosives. The platforms themselves had traditionally relied on strong and rigid design techniques for shock survivability. The resultant structures were said to be “shock hardened,” and were truly massive and imposing to would-be enemies. Indeed, from the US. Navy’s viewpoint, equipment is to be considered as flexibly mounted (i.e., base isolated) when a mounting frequency of less than 10 Hz is used! (Clements, 1972) The technique of shock hardening could not easily be used on electronics systems and missiles, so fluid viscous damping devices began to see use for the shock protection of this equipment. Early examples include the Lockheed MK88 and the Unisys MK92 Fire Control System Antennas, the Raytheon SPS-49 Search Antenna, and the Raytheon MK29 Seasparrow Missile Launcher. (Pusey, 1996) Later " " application of this technology combined fluid dampers and spring elements, and examples include the Litton MK49 Ship’s Navigator, Tomahawk, SM-2, and Seasparrow Missiles, and most large ballistic missiles, such as the Minuteman and Peacekeeper (MX). When the Cold War ended in 1990, much of the military’s fluid damper technology became declassified and available to the public through former Defense Department suppliers. Today, more than 60 buildings and bridge structures in the United States utilize F VD to control earthquake response, taking full advantage of technology developed during the Cold War era. (Constantinou & Symans,1992) In general, weapons grade shock within the military begins at peak translational velocities in the range of 120 in/sec. This can be compared to the 55 in/sec peak translational velocity of the 1994 Northridge, California earthquake. The upper limit of translational velocity that is considered "survivable" for military platforms is, of course, classified, but is generally considered to be in excess of 400 in/sec for structures designed to withstand near-miss nuclear detonations. Since this technology is now being used by both military and commercial projects, it is apparent that a commercial structure protected against earthquakes with fluid dampers should also be highly resistant to blast effects. 300 DESCRIPTION OF STRUCTURES Two steel moment resisting frame buildings with heights of 1 and 5-stories are used in the analysis. The typical floor—to- floor height is 14’-O”, with the exception of the first floor height of 16’-4” (See Figure 4). The footprint in all cases is 105 ft x 130 ft. The floor diaphrang are composed of cast- in—place concrete over metal deck. Each building is designed to conform to the Special Moment Resistance Frame (SMRF) requirements of the 1994 Uniform Building Code for seismic Zone 4 with S2 soil condition. This study was conducted to examine the stability of a SMRF only. The exterior wall and diaphragm must be designed to withstand, or absorb, the blast loading. For example, the State Department’s Office of Foreign Building Operations (FBO) requires that fenestrations be limited to 15% of each structural bay, and blast windows should be blast hardened (Gurrin & Remson, 1998). High strength glass may be laminated glass, polycarbonate, and plastic interlayer. (ASCE, 1990) Exterior column and wall elements may be blast hardened by conforming to the UBC Zone 4 Seismic requirements, or by the use of Fiber Reinforced Plastic (Crawford, 1997). l—STORY MODEL Two-dimensional models are constructed using Drain 2DX (Prakash., Powell, & Campbell, 1993). Steel beams and columns are modeled as plastic hinge beam-column elements. A bi—linear response is assumed with 5 percent plastic hardening. Yield strength is increased by approximately 20%, considering material over strength and dynamic strength increase (at a fast strain rate, a larger load is required to produce yielding than at a lower rate, (ASCE, 1997).) The Fluid Viscous Dampers are modeled as discrete damping elements mounted on chevron driver braces. Approximately 20% of equivalent critical damping by modal analysis is provided. An additional 5% of critical damping is assumed for global structural damping. A SMRF with dampers is called a Damped Frame and the SMRF without dampers is called a Bare Frame, in subsequent paragraphs. 3,000 lb TNT Blast At 100-Foot Standoff: A Bare Frame is subjected to a 3,000 lb TNT blast at 100—foot standoff distance. The blast wave propagates by compressing the air molecules with supersonic velocity, and it is reflected by the building, amplifying the over-pressure (Hinman, 1998). (See Figure 5) The Dynamic Time History Analysis indicates that the structural response parameter is insignificant for this loading, and no yielding occurs. Table 1: Maximum Response Parameters At Roof Level 3,000 lb TNT Blast At 20-Foot Standoff- The Bare Frame, Damped Frame and Shear Wall models are W- subjected to a 3,000 lb TNT blast at 20-foot standoff. A M concrete wall 78 feet long and 24 in—thick is used for shear . wall model. The Shear Wall is modeled as a linear elastic I ; ase eat g H panel element, and a 50% cracked section is assumed. This verifies that a minimum Set back distance 0f30 m The Bare Frame experiences a collapse mechanism due to (98feet) for the new US. embassy may be adequate to protect exeeSSiVe ptaStie hinge mtatioh (5% 01‘ more) Viscous lateral force resisting elements (Gurrin & Remson, 1998). The Damhers Prevent the eetlahse 1“ the Pamped Frame by majority of the blast energy is conserved by the kinetic energy redue‘hg dtlttehd PleStle hlhge retatteh- Thetpet'maheht _ in the structure since the duration efimpulse is very short in dlsplacement 15 5.44 in (0.028).. Permanent d1splacement 1s comparison to the natural period of the structure. Shock caused by the telloWlhgt 1) Slgmfieaht_b135t energy eaused spectra for dynamic amplification factors have been developed large PleStIC hlhges 1“ tremef, 2) ElaStle Straln (SPF mg) by Clough & Penzien (1993). Shock Spectra shows that the 7 Energy 1“ fiathes 15 hOt Slghtfieaht enough t0 brlng baCk larger the difference between impulse duration, and period of frames to the“ vertical POSttteh- The Shear Wall PFOdUCeS structure, the displacement amplification is smaller. (See eXtremely hlgh hase Shear, Slhee the dynamic amplification Figure 6) factor is much higher than that for SMRFs. This shear produces brittle shear failure unless additional Shear Wall is 3,000 lb TNT Blast At 40_F00t Standoff: provided or the existing walls are reinforced with extensive The Bare and Damped Frames are subjected to a 3,000 lb TNT Steel temtereemehh blast at a 40-Foot standoff distance. Minor yielding is observed for the Bare Frame. However, there is no significant Table 3: MaXimum Response Parameters At R00f Level difference between Bare and Damped Frames in structural Shear performance. Approximately 30% reduction in maximum Values Frame Frame Wall displacement is observed for this elastically responded '15P acement "1 1‘1 t - H H Damped Frame. m (0-068)* (0-04) (0-004) e colty 1 sec Table 2: Maximum Response Parameters At Roof Level Maximum Values lSp acement 1n r1 e oc1ty 1 sec ase ear g ' astlc ' otat1on o " a1 ure A cce eranon sec _ Figures 13, 14 & 15 show displacement, velocity, and ase ear g _ _ acceleration responses, respectively. Figure 13 shows - astte otatton - o _ _ maximum displacement occurs at approximately 0.2 seconds. Figure 7,8 & 9 show displacement, velocity, and acceleration, Fight e 16: 17 & 18 Show Energy Time HtStorieS for the Bare respectively. Displacement and velocity decayed at a faster Frames. Damped Frame: and Shear Walt mOdeIS, resPeCtiVBIY- rate for the damped frame. Maximum velocity and Hysteric energy (structural) demand IS greatly decreased for acceleration response occurs immediately after the blast. the Damped Frame. Figure 18 indicates that Strain energy (structural) is predominant. This causes a high base shear Figures 10 and 11 show Energy Time Histories for Bare and response Damped Frames respectively. Structural energy includes both _ . strain and hysteretic energy. These figures indicate that the Flgure 19 Shows FIUId Viscous Damper Response- majority of the input energy for the initial stage of response is conserved in kinetic energy. Figure 11 shows that Damping 5-ST0RY MODEL Energy is effective after the initial stage of response. Figure . _ 7 _ t 12 shows the Fluid Viscous Damper Response. Two-dimensmnal models are constructed usmg Dram 2DX. The same procedures are used as in the 1-story model. Again, approximately 20% of equivalent critical damping by modal analysis is provided at each floor level. The Fluid Viscous 301 Dampers are modeled as discrete clamping elements. Additional 5% of critical damping is assumed for global structural damping. 3,000 lb TNT Blast At 100-F00t Standoff- The Bare Frame is subjected to a 3,000 lb TNT blast at 100— foot standoff. Pressure decrements at upper floors are also considered. Nonlinear Time History analysis indicates that the structural response parameter is insignificant from this distance, and no yielding of members is observed. Table 4: Maximum Response Parameters At Roof Maximum Values Bare Frame 15p acement m H mm— o ase ear g 0 See Figure 20 for the displacement response. This figure shows classic displacement decay. 3,000 lb TNT Blast At 40-F00t Standoff: The Bare and Damped Frames are subjected to a 3,000 lb TNT blast at a 40—foot standoff. Yielding and permanent displacement is observed for both frames. Magnitude and quantity of plastic hinge rotation and displacement is significantly reduced for the Damped Frame. The permanent displacement is 13.36 in (0.015 roof drift) for the Bare Frame and 3.5 in (0.004 roof drift) for the Damped Frame. Figures 21 and 22 show plastic hinge distribution for the Bare and Damped Frames. Figure 23, 24 & 25 show displacement, velocity, and acceleration, responses respectively. Displacement and velocity decayed at a faster rate for the Damped Frame. Maximum velocity and acceleration responses occur immediately after the blast. Figure 26 and 27 show Energy Time Histories for the Bare and Damped Frames respectively. Structural energy includes both strain and hysteretic energy. These figures indicate that the majority of the input energy of the initial stage of response is conserved by kinetic energy. Figure 28 shows F VD Response. Results are similar to the 1 Story Model. 3,000 lb TNT Blast At 20-Foot Standoff: The Bare Frame, Damped Frame and Shear Wall models are subjected to a 3,000 lb TNT blast at a 20-foot standoff. A 5- story 78’ long x 24”-thick concrete shear wall is used for the Shear Wall model. The Bare Frame experiences the collapse mechanism at 2nd and 3rd levels due to excessive plastic hinge 302 rotation. Failures of connection occurs (plastic rotation of 5% or more) at 0.15 second and 9.5 inch roof displacement. The Shear wall produces extremely high base shear (24.5 g). Viscous Dampers prevent collapse in the Damped Frame by reducing plastic hinge rotation and drift. Maximum rotation in the Damped Frame is 5.0%, which is considered significant inelastic demand in frame connections. However, recent research indicates that some types of SMRF connections can be stable for this large demand (SSDA, 1999). The permanent displacement at roof is 22.2 in (0.026), and maximum displacement is 34 in (0.04) for damped frame. " Figures 29 & 30 Show plastic hinge rotation distribution for Bare and Damped Frames. Figures 31, 32 & 33 show displacement, velocity, and acceleration responses for the Bare Frame, Damped Frame, and Shear Wall models. Figures 34 & 35 show Energy Time Histories. Figure 36 shows Fluid Viscous Damper Response. DISCUSSION Fluid Viscous Dampers (FVD) conserve significant amounts of input blast energy throughout the duration of the structural response. After the blast occurs, a majority of the blast energy is conserved by kinetic energy, therefore the amount of damping does not affect maximum acceleration and velocity. Maximum velocity and acceleration occur shortly after at the blast impulse. Maximum displacement occurs at a somewhat later stage in the time history, therefore damping energy reduces strain energy contribution and reduces maximum displacement. Large blast impulse loading, such as blasts at standoffs of 20 feet or 40 feet overcomes kinetic energy and cause inelastic response in the structure. A FVD is a very effective tool in reducing this inelastic demand by adding large amounts of viscous damping energy dissipation. Using shear walls to control the blast impulse may produce the so-called “chasing tail” syndrome in structural design, ie., . adding shear wall increases the frequency and causes higher dynamic strain energy. The above one story example produces 36.5g base shear blast at 20-foot standoff. This shear force requires additional shear wall or reinforcement to this design. Energy(in—k) is expressed as; Ebl =E..+E .+E .+E .. ast kinetic strain hysterenc d ping _ For example, the one story damped frame With a 40—foot standoff produces the following energy time history. m-u-m-In— This study indicates that SMRF with FVD is a very effective system to increase structural performance in large blast loading. Exterior concrete skin should be connected to the diaphragm by out-of-plane connections only, rather than providing in-plane shear transfer. This out—of-plane connection should be flexible enough to reduce energy transfer to diaphragm and frames. Non-ductile moment frames may be retrofitted by FVD, since F VD reduce or eliminate inelastic demand in frames. lme ' metic ampmg tructura ‘ 0 (seconds) % % (strain + inelastic) l A CONCLUSION This study indicates the following results; 1.) 3,000 lb TNT blast at IOO-foot standoff distance does not cause significant structural responses to the candidate buildings. 2.) 3,000 lb TNT blast at 20-foot standoff distance may cause failures in Bare Frames. 3.) F VD reduces inelastic demand and story drift, and prevents failures in moment frames. 4.) FVD does not affect maximum velocity and acceleration responses in the structure. 5.) Concrete shear walls cause high strain energy demand and shear forces in the structure. 6.) SMRF with FVD is a very effective system to control the large blast loading. REFERENCES American Society of Civil Engineering, 1997, Design ofBIaSt Resistant Building in Petrochemical Facilities, Amerlcan Society of Civil Engineering, Reston, VA Clements, E-Ww 1972: Shipboard Shock and Navy Devices for its Stimulation Naval, Research Library Report NRL 7396 Clough & P311216“, 1993’» Dynamics of Structures, 2nd Edition, McGraw Hills Inc., NY Constantinou, M., & Symans, M., 1992, Experimental & Analytical Investigation of Seismic Response 0 Structures with Supplemental Fluid Viscous Dampers, NCEE '92‘0032 Crawford, Maluar, Dunn & Gee, I997, Retrofit ofRéififofced Concrete Columns Using Composite Wraps to Resist Blast Efirects, ACI Journal, American Concrete nstitute, Farmlngton Hills, MI 303 Gurvin & Remson, 1998, Anti-Terrorism Design of US. Embassies Structural Engineering World Wide: American Society of Civil Engineering, Reston, VA Hinman, 1998’ Approach for Designing C'Wilian Structures Against Terrorist Attack, Concrete Blast Eflectsv American Concrete Institute, Framington Hills, MI Pusey, H-C-a 1996a 50 Years of Shock and Vibration Technology, Shock and Vibration Information Analysis Center, Falls Church, VA Prakash, V., Powell, G.H. & Campbell, S.,1993 DRA [N 2 DX Version 1.0, Department of Civil Engineering, University of California, Berkeley, CA SSDA, 1999, Design & Performance ofthe SSDA Slotted Web Moment Frame Connection Detail, selsmlc Smmtural D351gn Associates, Inc. Laguna Nigel, CA ACKNOWLEDGEMENTS The authors would like to acknowledge Mr. Lon M. Determan, PE, and Ms. Staci Grabill of Marr Shaffer & r Miyamoto, Inc. for their assistance with this paper. Peak Reflected Pressure Figure 1: 3000 lb TNT Blast at 100—F00t Standoff Pressure (psi) Time (0.001 sec) 900 800 Peak Reflected Pressure 840 Figure 2: 3000 lb TNT Blast at 40-F00t Standoff 700 600 560 500 400 300 200 100 Pressure (psi) 280 3 4 5 6 7 8 Time (0.001 sec) 5000 4500 Peak Reflected Pressure 4400 Figure 3: 3000 lb TNT Blast at 20-F00t Standoff 4000 a: 3500 m 55 3000 ° 2500 2000 Pressur 1500 1000 500 Time (0.001 sec) 304 INDICATES EDS TYPICAL W27><94 W14X176 W27X94 W27X94 W30X1 16 W30X1 16 W14X311 W14X159 1 STORY 5 STORY (T1=O.5 SEC) (T1=1.4 SEc) Building Models Figure 4- OVER PRESSURE OVER PRESSURE REFLECTED PRESSURE , I ’2’ ’1’ t ,z’ /’ CENTER ’ I 0F BURST / STANDOFF ,/ I’ / OVER ,z’ / PRESSURE Blast loads on a building (Hinman, 1998) Figure 5 305 Maximum Displacement Response Ratio Triangular Pulse 0.0 0.2 0.4 0.6 0.8 1.0 1.2 771.4 1.6 Ratio t1/T = (Impulse Duration)/Period Figure 6: Shock Spectra (Clough & Penzien, 1993) 306 1.8 2.0 Figure 7: Response Displacement at Roof Level l-Story Mode] at 40-Foot Standoff I I»; 2.00 » Rim-7v f 1.50 mm.” a 1.00 J—_. a 333 W a . a -0.50 M. “w— 3" -1 00 fl n . -1.50 _ -2.00 0.0 0.2 0.4 0.6 ' 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Time (sec) —— Bare Frame —Damped Frame Figure 8: Velocity Response at Roof Level l-Story Model at 40-Foot Standoff E E V g H O ;> 0.0 0.2 0.4 0.6 0.8 1.0 1.2 7' 1.4" 1.6 1.8 2.0 Time (sec) —— Bare Frame —Damped Frame Figure 9: Acceleration Response at Roof Level l-Story Mode] at 40-Foot Standoff 20000 ‘ 1.76E+04 i.n/secz (max.) 2 Acceleration (in/sec ) 15000 10000 5000 -5000 Time (sec) —— Bare Frame —Damped Frame 307 Figure 10: Energy Time History l-Story Bare Frame at 40-Foot Standoff ,_. O O O 00 O O A "2‘ .E Q 500 “.3 a 4:. o o N O O 0.6 . , I . . 1.4T 1.6 —'Structural Damping + Structural -—Kinetic + Damping + Structural Figure 11: Energy Time History l-Story Damped Frame at 40-Foot Standoff ._. O O O 00 O O Energy (in-k) O\ 8 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 " 1.6 1.8 a 2.0 7 7 7 _ Time (sec) 77 Damping + Structural —Kinetic + Damping + Structural Figure 12: Fluid Viscous Damped Response l—Story Damped Frame at 40-Foot Standoff 300 200 ,— O O .1. o o Viscous Force (k) 0 x N O O -2.5 -2.0 -1.5 -1.0 -0.5 ., 0.0 0.5 1.0 . 1.5 2.0 2.5 Total Deformation (in) 308 Figure 13: Displacement Response at Roof Level l—Story Mode] at 20-Foot Standoff ._.... NA H O A E a 5 E Q .2 Q .E Q liamiaedllrame ;Shear Wall —— Bare Frame (collapse) Figure 14: Velocity Response at Roof Level l-Story Model at 20-Foot Standoff Velocity (in/sec) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 —— Bare Frame (Collapse) Figure 15: Acceleration Response at Roof Level 17Sioi‘y Model at 20—Foot Standoff “A U Q : 'C‘u :1 G .5 fl 5-: 3 d.) O U 4 1.0 Time (sec) bamped Frame —‘Sheai Wall 309 Figure 16: Energy Time History l—Story Bare Frame at 20-Foot Standoff Energy (in-k) 0.0 0.2 0.4 0.6 ' 0.8 1.0 1.2 1.4 1.6 1.8 Time (sec) —— Structural Damping + Structural —Kinetic + Damping + Structural Figure 17: Energy Time History l-Story Damped Frame at 20—F00t Standoff Energy (in—k) 0.0 0.2 0.4 0.6 0.8 1.0 L2 . 1.4 1.6 1.8 2.0 Time (sec) — Structural Damping + Structural —Kinetic + Damping + Structural 310 Energy (in—k) Viscous Force (k) Displacement (in) Figure 18: Energy Time History 1-Story Shear Wall at 20-Foot Standoff 10000 ‘ 8000 6000 4000 2000 0.4 0.6 0.8 1.4 L6 1.8 2.0 Figure 19: Fluid Viscous Damped Response l-Story Model at 20-Foot Standoff 1000 " ’ 800 600 400 200 -200 —400 -600 Figure 20: Displacement Response at Roof Level 5-Story Bare Frame at 100-Foot Standoff P3 u: o )— OUIHUIN é: U! I P“ l U. _ l N I N Ln 311 INDICATES MAGNITUDE OF PLAST|C HINGE (TYPICAL) Bare Frame at ,40—Foot Standoff 2.8% Max. Plastic Hinge Egtation Figure 21 Damped Frame at 40—Foot Standoff 0.79% Max. Plastic Hinge Rotation Figure 22 312 25 20 15 10 Displacement (in) 3 E 5‘ '5 3 :9 > 9000 8000 7000 6000 5000 4000 3000 2000 1000 Acceleration (in/secz) u H O O O 0 Figure 23: Displacement Response at Roof Level S—Story Mode] at 40—Foot Standoff fifigfim‘: 0 1 2 3 4 5 6 7 8 9 1 0 Time (sec) —— Bare Frame ——Damped Frame Figure 24: Velocity Response at Roof Level 5-Story Model at 40-Foot Standoff 78.24E+03 in/secz (max.) Figure 25: Acceleration Response at Roof Level 5—Story Model at 40-Foot Standoff Time (sec) —— Bare Frame ——Damped Frame 313 Figure 26: Energy Time History 5—Story Bare Frame at 40-Foot Standoff "v- F’Efi r, V - ‘l ~77 ‘— ._. N O O O L? E E : a — Structural Damping + Structurali;kinetic + Damping Structural Figure 27: Energy Time History S-Story Damped Frame at 40-Foot Standoff Energy (in—k) Time (sec) —— Structural Damping + Structural -—Kinetic + 7+ Structural 7 Figure 28: Fluid Viscous Damped Response 5-Story Damped Frame at 40—Foot Standoff 600 400 200 ~200 Viscous Force (k) 0 —400 -600 , -1.5 —1.0 -0.57 , , 0.0 0.5 1.0 15 Total Deformation (in) 314 /® INDICATES PLASTIC / ROTATION LARGER THAN 5% Bare Frame at VZQr—Froot StancIoff 14.3% Max. Plaatig: Hinge Rotation (failure) Figure 29 Damped Frame 01; 20—Foot Standoff 5.0% Max. Plastic Hinge Rotation Figure 30 315 Figure 31: Displacement Response at Roof Level 5-Story Model at 20-Foot Standoff Displacement (in) 0 1 0 Time, Se ,7 ,, ._ , Damped Frame —Shea.r Wall Figure 32: Velocity Response at Roof Level 5-Story Model at 20-Foot Standoff Displacement (in) Time (sec) —— Bare Frame Figure 33: Acceleration Response at Roof Level 5-Story Model at 20-Foot Standoff Acceleration (in/secz) Time (sec) — Bare Frame Damped Frame —Shear Wall 77 316 Figure 34: Energy Time History 5-Story Bare Frame at 20-Foot Standoff .— 140000 120000 100000 80000 60000 Energy (in-k) 40000 20000 Figure 35: Energy Time History 5-Story Damped Frame at 20-Foot Standoff 120000 100000 A O\ 00 O O O O O O O O O O O O Energy (in—kip) Figure 36: Fluid Viscous Damped Response 5-Story Damped Frame at 20—Foot Standoff 1000 , A as 500 ‘9 r E I fit 0 .A‘IICI-‘I‘--=E!===:~ 3 - " ' Q .g -500 > -1000 —1500 -4 -3 -2 -1 0 1 2 3 4 Total Deformation (in) 317 318 ...
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Miyamoto H.K & Taylor D. - Structural Control of Dynamic Blast Loading Using Passive Energy Diss

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