Tài liệu Structures congress 2017 blast, impact loading, and response of structures

Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Structures Congress 2017 Blast, Impact Loading, and Response of Structures Selected Papers from the Structures Congress 2017 Denver, Colorado April 6–8, 2017 Edited by J. G. (Greg) Soules, P.E., S.E., P.Eng Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Struc S cturres Cong C gresss 20017 Blast, Impac I ct Loa adingg, andd Respponsee of Strructures SELECTE ED PAPER RS FROM THE T STRUC CTURES C CONGRESS S 2017 Apriil 6–8, 201 7 Denver, Coloraddo SPON NSORED BY Y The Strructural En ngineering Institute (S SEI) of the American A Society of C Civil Enginneers ED DITED BY J. G. (Greg) Soules, P.E., S.E., P.Enng Published P by b the Amerrican Societyy of Civil En ngineers Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. 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Errata: Errata, if any, can be found at https://doi.org/10.1061/9780784480397 Copyright © 2017 by the American Society of Civil Engineers. All Rights Reserved. ISBN 978-0-7844-8039-7 (PDF) Manufactured in the United States of America. Structures Congress 2017 iii Prreface Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. The Structures Congress C hass a robust tecchnical proggram focusinng on topics important too Strucctural Engin neers. The papers in the proceeding g are organizzed in 4 voluumes ume 1 includ des papers on n Blast and Impact I Loadding and Ressponse of Strructures Volu Volu ume 2 includ des papers on n Bridges an nd Transporttation Structuures Volu ume 3 includ des papers on n Buildings and Nonbuillding and Sppecial Structtures Volu ume 4 includ des papers on o Other Strructural Enggineering Toppics includinng; Business and Professional Practice, Natural N Disaasters, Nonsttructural Syystems and C Componentss, orensics Educcation, Research, and Fo Acknow A wledgm ments Prep paration for the Structurres Congress required ssignificant tiime and efffort from thee mem mbers of th he National Technicall Program Committeee, the Loccal Planningg Com mmittee. Mucch of the succcess of the conference c rreflects the ddedication annd hard workk by th hese volunteeers. We would w like to thank GEIICO and Peaarl for Sponssoring the Congress procceedings andd supp porting the Structures Co ongress in su uch a generouus way. The Joint Progrram Committtee would like l to acknnowledge thee critical suupport of thee spon nsors, exhibiitors, presen nters, and mo oderators whho contributted to the suuccess of thee confference throu ugh their parrticipation. o dedicated volunteerrs and staff, f, we wouldd like to thank you for On behalf of our nding your valuable v timee attending the t Structurees Congresss. It is our hhope that youu spen and your y colleag gues will ben nefit greatly from the infformation prrovided, learrn things youu can implement i and a make pro ofessional co onnections thhat last for yyears. Sinccerely, J. Grreg Soules, P.E., P S.E., P..Eng, SECB, F.SEI, F.A ASCE © ASCE Structures Congress 2017 iv Contents Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Blast and Impact Loading and Response of Structures Performance of Girder Bridges under the Composite Action of Blast Loads and Earthquakes ............................................................................................. 1 Jingyu Wang, Wancheng Yuan, and Fengming Wang Blast Response of 60 MPa Reinforced Concrete Slabs Subjected to Non-Confined Plastic Explosives ............................................................................. 15 Fausto B. Mendonca, Girum S. Urgessa, and José A. F. F. Rocco Calibration of Barge Models for the Reliable Prediction of Impact Force on Bridge Piers ............................................................................................................... 27 D. S. Saini and B. Shafei Experimental and Analytical Alternate Load Path Analysis for Reinforced Concrete Flat Plates .................................................................................................. 37 Ahmed Khalil and Sarah Orton New Methodology for Designing ATFP Using the Modified Alternate Load Path Method .............................................................................................................. 51 Ayman Elfouly, Ahmed Khalil, and Nabil A. Rahman Effects of Blast-Induced Permanent Deflections on the Performance of Load-Bearing Steel Elements in Fire ...................................................................... 66 L. Magenes, T. J. Mander, and M. A. Morovat Experimental and Numerical Analysis for Non-Load Bearing Sandwich Wall Panels for Blast Mitigation ............................................................................. 77 A. E. El-Sisi, A. Saucier, H. A. Salim, and M. Nawar Progressive Collapse Performance of Buildings and the Contribution of Infill Walls ................................................................................................................. 86 Kai Li, Curtis Wood, and Halil Sezen Dynamic Response of Reinforced Concrete Bridge Piers Subjected to Combined Axial and Blast Loading ........................................................................ 98 Olaniyi Arowojolu, Muhammad Kalimur Rahman, and Baluch Muhammad Hussain © ASCE Structures Congress 2017 Explosive Test Chamber: Analysis and Design.................................................... 110 Yousef Alostaz and Asher Gehl Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Nonlinear Dynamic Analysis on the Progressive Collapse Response of an RC Frame with Perforated Infill Walls ................................................................ 119 Sidi Shan, Shuang Li, Changhai Zhai, and Lili Xie Deflagration Load Generator Blast Load Testing of an ISO Shipping Container and Blast Resistant Wood Building .................................................... 130 T. H. Anderson, B. J. Horn, J. K. Thomas, and L. Magenes Modeling and Testing of Shear Connections with Beams under Tension Membrane Loading ................................................................................................ 153 David Holgado, Robert Driver, and Darrell Barker Is the Load Transfer Mechanism of Each Story in a Multi-Story Building the Same Subjected to Progressive Collapse? ...................................................... 165 Jun Yu and Ji-wei Tian The Effects of Bracing on the Behavior of RC Multi-Story Frames to Resist Progressive Collapse ............................................................................................... 180 Kai Qian, Yang Yu, Yue-Ming Wang, and Bing Li Performance of Precast Concrete Planks Subjected to Hail Impact Loads—A Case Study ............................................................................................. 187 Dziugas Reneckis, Vicki Lam, and Remo Capolino Development of Blast Response Limits for Load-Bearing Prestressed Concrete Panels Using Full-Scale Shock Tube Test Data ................................... 197 Thomas J. Mander, Michael J. Lowak, and Michael A. Polcyn The Current State of Automated Building Design and Fast-Running Analysis for Vulnerability Studies ........................................................................ 209 S. A. Minkoff, J. F. Nichols, and G. Doyle Acceptance Criteria for the Nonlinear Alternative Load Path Analysis of Steel and Reinforced Concrete Frame Structures ............................................... 222 J. M. Weigand, Y. Bao, and J. A. Main Alternative Load Path Analysis of a Prototype Reinforced Concrete Frame Building ....................................................................................................... 233 Yihai Bao, Joseph A. Main, and H. S. Lew An Overview of Missile Impact Tests on Steel-Plate Composite (SC) Walls......................................................................................................................... 245 Joo Min Kim, Jakob Bruhl, Jungil Seo, and Amit Varma © ASCE v Structures Congress 2017 vi Preliminary Investigation of Local Failure Modes in Steel-Plate Composite Walls Subjected to Missile Impact ..................................................... 256 Joo Min Kim, Jakob Bruhl, Jungil Seo, and Amit Varma Forensics Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Lovettsville Water Tank Column Rupture Forensic Investigation ................... 262 Donnell Duncan Investigation into the Failure of a Long-Span Glued Laminated Beam............ 276 A. M. Shuck, J. A. Porto, and K. K. Sasaki Structural Building Condition Reviews: Beyond Distress .................................. 289 James A. D’Aloisio Observations of Snow Load Effects on Four School Buildings in New England ........................................................................................................... 302 R. A. Daniel Bass and Michael O’Rourke Determining the Effects of Construction Quality, Age, and Deterioration on the Resistance to Loads ..................................................................................... 314 William L. Coulbourne © ASCE Structures Congress 2017 1 Performance of Girder Bridges under the Composite Action of Blast Loads and Earthquakes Jingyu Wang1; Wancheng Yuan2; and Fengming Wang3 1 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji Univ., No.1239 Siping Rd., Yangpu District, Shanghai 200092. E-mail: [email protected] 2 State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji Univ., No.1239 Siping Rd., Yangpu District, Shanghai 200092. E-mail: [email protected] 3 Shandong Provincial Communications Planning and Design Institute, No.576 West Wuying Mountain Rd., Tianqiao District, Jinan City 250000. E-mail: [email protected] Abstract The research focuses on the dynamic performance of girder bridges and the applicability of cable-sliding friction bearing subjected to blast load and earthquake. In order to accomplish this, numerical simulation and scale model test are performed. In numerical simulation, two seismic waves combing with blast load of 450kg TNT are applied to the girder bridge separately by using software LS-DYNA. After analyzing the area of damage and longitudinal displacement, results show that the most remarkable displacement change of main girder appears when blast occurs at the time that seismic response arrives at the maximum value. Based on the existing research, cable-sliding friction bearing is suggested to be adapted. Next, scale model test is conducted considering two different damping bearing systems and three series of tests are performed to verify the effectiveness of the cable-sliding friction bearing system. The data collected from the test shows that the bearing could prevent beam falling and therefore improve the safety of girder bridges. Keywords: Girder bridges; Composite action; Blast load; Earthquake; Numerical simulation; Scale model test; Cable-sliding friction bearing. INTRODUCTION Recently, the transportation of dangerous goods is increasing, which lead to frequent vehicle explosion accidents. Besides, terrorist blast attacks happen frequently in the word. All these factors make blast load become a potential threat to the safety of bridge structures. However, blast effect has not been considered in design and construction standards for bridges in China until now. Specific construction requirements for anti-explosion properties of bridges have not been put forward. The report No.645 of National Cooperative Highway Research Projects “Blast-resistant Highway Bridges: Design and Detailing Guidelines” is the relatively authoritative literature among current © ASCE Structures Congress 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. anti-explosion research (Williamson 2010). But only simple guidance is provided in this reference, and comprehensive information about failure modes for components of bridges are failed to provide (Yi et al. 2013). On the contrary, the concept of seismic design for bridges becomes prominent in recent years and corresponding methods are relatively mature as many specifications have been amended or completed. Thus, whether bridges that are based on seismic resistance have the ability to withstand the impact of blast load needs to be further researched. In addition, when an earthquake occurs, it’s highly possible that trucks loaded with dangerous goods will explode due to crashes. Widespread damage is likely to happen under the composite action of blast load and earthquake. Thus, the design of bridges under multiple extreme loads especially blast load and earthquake has become the forefront of current research. From 2003, the group of Pr. George C. Lee for the disaster research center of the state university at Buffalo has conducted the research on design of bridges subjected to multiple hazards based on probability with the support from federal highway in US. The concept for design of load and resistant coefficient under multiple hazards was put forward and a variety of loading combinations were taken into consideration (George et al. 2011). The frame of steel-tube-concrete piers was regarded as the research object by Fujikura, and performance of piers were observed under the effect of blast and earthquake respectively (Fujikura et al. 2008). An effective method for calculating the load combination coefficient was put forward and analyzed considering the combination of earthquake and heavy trucks as the research object (Sun Dezhang and Sun Baitao 2012; Sun Dezhang 2013). In the research, the steel-tube-concrete and steel-protecting-tube piers which are applicable to aseismic design were analyzed. And result showed that the anti-explosion performance has been improved significantly compared with the ordinary concrete piers (Fouche et al. 2013; Kyei et al. 2014). To sum up, the explosion-proof research of bridges is still in its infancy at present. Combination effect of blast load and earthquake subjected to bridges has not been involved basically. To bridge the gap, the focal point of this paper is to investigate the dynamic performance of girder bridges and applicability of cable-sliding friction bearing under composite action of blast load and earthquake. Various methods including numerical simulation and experimental test are involved in the test. As for numerical simulation, two different seismic waves combing with blast load of specific magnitude (450kg TNT) are applied to specific girder bridge respectively. The time when explosion happens is settled to distribute evenly after the time that the largest seismic response of bridge occurs. Based on the research of numerical simulation, cable-sliding friction bearing is suggested to be adapted which could limit the large relative displacement between main girders and piers caused by earthquake and blast load. Further, scale model test is conducted considering two different damping bearing systems including cable-sliding friction bearing system and non-cable friction bearing system. Three series of tests are © ASCE 2 Structures Congress 2017 3 perfo ormed in th he research including blast b loadingg test, earthhquake loadding test and comp posite test of the two ex xtreme loadss. The dynam mic characteer of the moodel bridge iis observed and ap pplicability of o the cablee-sliding fricction bearinng under varrious loadingg cond ditions could d be evaluated. Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. RES SPONSE AN NALYSIS OF O GIRDER R BRIDGE U UNDER CO OMPOSITE E ACTION OF BLAST B LOA AD AND EA ARTHQUA AKE Th he purpose of o the analyssis is to expllore the reacction and dam mage condittion of girdeer bridg ges under composite c action a of blast load aand earthquaake. Two vvariables arre invesstigated in this researcch: damage area and longitudinall displacem ment. Generaal nonliinear dynam mic analyzin ng software LS-DYNA is used in tthe simulatioon, and blasst load is conducted d by using th he computerr system ConnWep. In n the study, a 30m span girder g bridgee is regardedd as the prottotype of whhich the crosss section for main girder is com mposed of fiive pieces off boxes. Thee concrete is simulated byy g Solid164 in i the finite element mod del (Yang Yu Yuqi et al. 2012; Wu Jiannqiang 2006)). using Elasttic material is used to simulate the capping beaam without considering the damagee. BEA AM161 is ad dopted to siimulate the reinforcemeent, stirrup and pre-streessed ribbonn. Rein nforcement and a concretee are modelled and divvided separrately, and tthen coupled togetther. Laminaated rubber bearing is substituted by using coontact (Zhanng Tao et all. 2013 3). For the in nsignificant interaction between b maiin girders annd piers undder blast loadd, main n girder is caalculated ind dividually wiithout considdering the efffect of barrier in order to imprrove the calcculation efficciency (see Figure F 1). Figure 1. 1 The model of o main girderr and reinforccement Th he explosion n center is fixed at girderr No.3 with 1.2m heightt from the deeck verticallyy and the amountt of 450kg TNT is co onsidered inn the subseequent anallysis withouut considering the collapse off the main girder (Liu Chao 20122). Two seismic wavessTriniidad and EL L Centro of which the response r vallue for displlacement is different arre seleccted as the earthquake load. Wheth her the respponse of strructure undeer compositte actio on is influen nced by thee displacemeent of seism mic wave coould be invvestigated byy comp parative analysis. The peeak acceleraation of bothh seismic wavves is adjustted to 0.6g inn orderr to make th he seismic response r of bridges moore apparentt. For Triniddad, the tim me when n the blast lo oad happenss is settled to be at threee different ttime spots inncluding 10ss, © ASCE Structures Congress 2017 4 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. 15s and a 20s in th he condition for composiite action. Besides, for E EL Centro, thhe time whenn the blast b load haappens is setttled to be at four time sspots includding 5s, 15s, 25s and 355s for composite acction. Th he damage condition c off main girdeer under com mposite actioon of Triniddad and blasst load or EL Centtro and blasst load are listed in Tabble 1. For thhe longitudinnal action oof hquake, no coupling c efffect appears while the vvertical imppact of mainn beam takees earth placee. So, the damage d areaa does not expand. e Butt little increease appearss in terms oof longiitudinal leng gth for EL Ceentro compaaring with Trrinidad. Tablee 1. The damag ge area of maiin girder undeer composite aaction of blastt load and earrthquake ge Damag Trinid dad Areaa Centtro after Earthquake E Blaast at 15s Blast at 20s after after Earrthquake Earthquake Length((m) 4.6 4.8 4.6 4.6 Width(m m) 3.5 3.5 3.5 3.5 Blast at 15s Blaast at 25s Blast at 35s afterr after after Earthquuake Earrthquake Earthquake Damag ge EL L Blast Blaast at 10s Areaa Blast Blast B at 5s afteer Earthquake Length((m) 4.6 4.6 5.0 5.0 4.8 Width(m m) 3.5 3.5 3.5 3.5 3.5 Laarge displacement of veertical reboun nd for mainn girder wouuld not causee much effecct if on nly the blastt occurs. Ho owever, wheen earthquakke appears aat the samee time, largeer horizzontal displaacement of the t infrastruccture may taake place at the instant of pop-up oof main n girder. It iss very likely y that main beam b falls ffrom the beaaring and caause series oof disassters. The lo ongitudinal displacemen d nt of main ggirder under composite action of EL L Centtro and blast load is sh hown in Figu ure 2. For bboth Trinidaad and EL C Centro, largge mutaation of the longitudinall displacemeent occurs att the instantt of explosioon. The mosst remaarkable displlacement chaange of main n girder appeears when blast occurs aat 5s after thhe earth hquake happens. a) Blast at a 5s after eartthquake happeens © ASCE b) Blasst at 15s after earthquake happens Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Structures Congress 2017 5 c) Blast at 25s after earrthquake happ pens d) B Blast at 35s affter earthquak ke happens Figure F 2. The longitudinal l displacement d of o main girderr under compoosite action (E EL Centro) As A for wave Trinidad, the t incremeent of displaacement undder compossite action iis limitted and littlee influence is i made to th he main girdder. In orderr to display the variationn moree specificallly, the long gitudinal displacement under EL Centro andd four otheer comp posite loadin ng condition ns is shown in Table 2. The most rremarkable ddisplacemennt chan nge for main girder whicch is up to 12.7cm appeears when bllast occurs aat 5s after thhe earth hquake happ pens. Besides, the chang ge of displaccement for tthe rest of tthree loadingg cond ditions are all under control which su uggests that tthere has a rrisk of beam falling whenn blastt occurs at the t time thaat seismic reesponse of m main girder arrives at thhe maximum m valuee. Tablee 2. Compariso on of the longiitudinal displa acement for m main girders (E EL Centro; Unit: cm) Loadin ng Condition Only Earthquuake Com mposite Action Variationn Blast B at 5s after Earthquake Happens 10.0 -2.7 12.7 Bllast at 15s afterr Earthquake Happens H 10.0 11.8 -1.8 Bllast at 25s afterr Earthquake Happens H 10.0 14.1 -4.1 Bllast at 35s afterr Earthquake Happens H 9.9 9.1 0.8 BLE-SLIDIN NG FRICTIION BEAR RING CAB In n order to avoid a the beeam falling under compposite actionn, an effecttive isolationn beariing known as a the “cablee-sliding fricction bearingg” is suggessted to be addapted (Yuann Wanccheng et al. 2010; Yuan n Wancheng et al.2012). The bearingg, which takkes advantagge of bo oth the frictio on sliding reesistance and d the restrainnt capability of the cablees, consists oof essen ntially a conventional po ot bearing, high strength restrainer cables on botth sides and a shearr bolt in the middle if neecessary (seee Figure 3). © ASCE Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Structures Congress 2017 Figurre 3. Schematiic diagram of a fixed type c able-sliding frriction bearing Th he performaance criteria for the cablee-sliding fricction bearingg are summaarized. Undeer mino or and modeerate compossite action, the t shear boolt in a fixedd-type bearinng would noot break k so that no replacemen nt of the bearring will be necessary. IIn a sliding-ttype bearingg, the sliding s betw ween the staiinless steel plate p and thhe Teflon pllate serves tto isolate thhe superstructure from horizonttal ground motions m and ddissipate eneergy by friction while thhe mation of thee bearing sh hould be lesss than the ddesign free ddisplacementt. expeected deform Undeer a severe condition th hat causes the t shear boolt to breakk, the fixed--type bearingg functtions as a sliiding-type bearing to miitigate the trransmission of earthquakke forces andd dissip pate energy,, while the excessive reelative displlacement bettween the suuperstructurre and the t pier caussed by composite action can be restraained by thee cable compponents. Th he idealized hysteretic lo oad-displaceement responnse envelopee of the bearring is shownn in Fiigure 4, which is superp posed by thee lateral loadd-displacemeent responsee envelope oof slidin ng friction bearing b and cables. In Figure F 4, denotes thhe elastic stiffness of thhe slidin ng friction bearing; b is i defined ass the tensilee stiffness off each cablee member; deno otes the desig gn free displacement wh hen the bearinng is in norm mal service lload. Figurre 4. Idealized hysteretic loa ad-displacemeent response en nvelope of thee bearing (horrizontally) © ASCE 6 Structures Congress 2017 7 PERFORMANCE OF GIRDER BRIDGE WITH CABLE-SLIDING FRICTION BEARING Design of Scale Model Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Regarding a 40m span simply-supported concrete bridge as the prototype, scale model test is carried out. Based on the existing research (Zhang Yu et al. 2016), cable-sliding friction bearing is utilized to limit the large relative displacement between main girders and piers caused by blast load and earthquake. The similarity relationship between model and the prototype is attained by dimension analysis (see Table 3). In the production process of model, organic glass is being used to simulate the fiber-reinforced concrete, and lead is added to meet the requirements of similar weight. Based on the principle of equivalent stiffness, the vertical and horizontal bending stiffness remain equivalent between the prototype and model, and the influence of axial stiffness and torsional stiffness are ignored. Model bearing is obtained from the bearing factory. Table 3. Similarity relation between model and the prototype Item Material Property Physical Quantity Relation Strain ε =1 Stress σ = Ratio of Similitude 1 0.0699 Modulus of Elasticity E 0.0699 Poisson’s Ratio μ Density ρ 1 / 2.237 MDC 1/80 MDC = Area S = 1/6400 Displacement δ = 1/80 =1 Rotation θ 1 Load and Internal Force F = 1.092e-05 Force Bending Moment M = 1.365e-07 Mass m = 4.368e-06 Stiffness k = 8.737e-4 Time t Dynamic Character Frequency f = MDC =1 Length l Geometric Features Remark . / = 1/ 7.071e-2 DLC 14.142 DLC Damp c = / 6.178e-05 Velocity v = / 0.177 Acceleration a = / 2.5 DLC Note: “MDC” means “Model Design Control” and “DLC” means “Dynamic Loading Control”. © ASCE Structures Congress 2017 Simulation of Blast Load Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. The most important question needed to be dealt with in this test is how to simulate the blast load. According to literature (Yang Xiumin 2010), under the impact of solid projectile and static charge contact explosion, the reinforced concrete target boards of different thickness have four kinds of typical failure forms including pitting, damage, going through and cutting. Whether the projectile impact or contact explosion, reinforced concrete plates are both under an instantaneous high-pressure pulse rendering the similar brittle failure characters, and their failure mechanisms are the same. Therefore, the equivalent relationship between projectile impact damage and contact explosion damage could be used to solve the problem of contact explosion. For a target board of certain thickness, when a projectile goes forward with a velocity of v and the mass of m, the impulse it has is mv and the kinetic energy is m /2. When it hits the center of target plate, its speed drops to zero, and the damage effect made to the target board is equivalent to the damage effect made by surface contact explosion with a certain amount of explosives . As the projectile impact and impulse is relatively small, the energy equivalence principle could be took advantage of to get the corresponding equivalent amount of TNT. In the test, the whole structure is assumed to be at the linear elastic state without considering damage. A high-elastic sphere (0.0526kg) in the state of free fall or sinusoidal oscillation is used to simulate the blast impact. The principle of energy conservation is applied to get the falling kinetic energy of the sphere, and this energy is exactly the energy released from the explosion happened near the deck. Scale Model Test For comparative analysis, two different damping bearing systems are tested including cable-sliding friction bearing system and non-cable friction bearing system. Three kinds of loading conditions are conducted including blast loading test, earthquake loading test and composite test of these two extreme loads. Six different seismic waves are selected as incentives, testing and evaluating the applicability of the cable-sliding friction bearing under different loading conditions. Detailed information is shown in Table 4. Shake table, high-elastic sphere, acceleration sensors, laser displacement sensors, strain gauges and data acquisition system are used in the test. With the help of data acquisition system, the response of acceleration, displacement and strain from different parts of the model under various loads are collected. After assembling and equipment calibration, the completed test model is obtained (see Figure 5). © ASCE 8 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Structures Congress 2017 9 Figure 5. Assembled A testt model Tablee 4. Loading co ondition of the scale model test Model Loading Condition C Serial Wave Peaak Load Number N Form Acceleraation(g) T Time(s) E1 EL Centro 1.55 2.82 E2 CHICHI1 0.66 12.72 0.11 12.72 0.22 12.72 0.11 12.72 0.22 12.72 0.11 12.72 0.11 12.72 0.22 12.72 mpact Directionn Im Posittion Disttance(cm) B1 Above A the bridgge Mid-sspan 10 B2 Along A the bridgge At the End 10 B3 Cross C the bridgee Mid-sspan 10 E3 Only Earthquake (Longittudinal) E4 E5 E6 E7 CFBS E8 BS) (NFB E9 Only Blast Load CHICHI2 CHICHI3 CHICHI4 CHICHI5 Combiination CB1/2/3 C E1+B1/B2/B3 Efffect CB4/5/6 C E3+B1/B2/B3 Note: “CFBS” mean ns “Cable-sliding Friction Beearing System”” and “NFBS” m means “Non-cable Friction ng System”. Bearin Perfformance off the Girderr Bridge  Dynamic D Peerformance of o the Girderr Bridge undder Blast Loaad Acceleration A versus v time curve of maain girder at the mid-spaan is in dampped harmoniic vibraation form when w impactt of elastic sphere s occuurs at the miiddle, and thhen return to origiinal state afteer a few seconds. This phenomenon p n shows that the whole sstructure is inn elastic state as beeing assumeed (see Figurre 6). The m most dramaticc response aappears at thhe m girder suffers from m the impact along the bridge at thhe impaact location. When the main end, the longitud dinal accelerration of maain girder beecomes the most dramaatic, and thenn © ASCE Structures Congress 2017 10 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. the dynamic d resp ponse transffers to cappiing beams aand piers thrrough bearinng. In such a case,, the acceleraation respon nse of cappin ng beam is loower than m main girder because of thhe existting cables (ssee Figure 7(a)-(b)). Figure F 6. Mid-span accelera ation versus tim me curve of m main girder (a) En nd of the main n girder (b) Capp ping beam Figure 7. Acceeleration versus time curves when impacct applied alon ng the bridge aat the end Under U the imp pact of blastt load, the diisplacement versus time curve is witth the similaar trend d as acceleraation. Longittudinal and horizontal h blast impact m make large ddisplacemennt deviaation betweeen main gird der and cappiing beam (seee Figure 8(aa)-(b)). (a) Longitudinal L direction d (b) Horizoontal direction n Figurre 8. Displacem ment versus time curve betw ween main girrder and capp ping beam wheen longitudinaal and horizontal impact applied © ASCE Structures Congress 2017  11 Dynamic Peerformance of o the Girderr Bridge undder Earthquaake Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. While W six diffferent seism mic waves occcur along tthe bridge, tthe dynamicc accelerationn respo onse of main n girders at the t longitudiinal directionn is significantly lower than cappingg beam m in CFBS comparing g with NFB BS. The effficiency on reducing aand isolating vibraation of cablle-sliding friiction bearin ng under seissmic effects at different level is veryy high (see Figuree 9(a)-(c)). Adding cab bles does noot affect thee good shocck-absorptionn perfo ormance of the t original bearing. b (a)At the bottom off piers (b) A At the middlee of capping beeam (c)At the end of main ggirder Figurre 9. Longitud dinal accelerattion versus tim me curve of b ridge structurres while eartthquake occurrs along th he bridge Th he maximum m displacem ment between n main girdder and cappping beam iss up to 3mm m undeer the longitu udinal earthq quake, and response r of aall the bearinng is consisttent. Besidess, the strain s of pieers at differeent height arre relativelyy small at thhe level of tthe parts peer milliion, and retu urn to the orriginal state after earthqquake in botth CFBS andd NFBS (see Figure 10(a)-(b))). This indiccates that all the piers aare in elasticc range, andd the internaal forcee of piers iss small. Mo ost of the in nertial forcees are cut ooff because of the cablle beariing. © ASCE Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Structures Congress 2017 (a) Longitudiinal strain verrsus time curv ve of o piers at the bottom 12 (b) Displlacement betw ween the main girder and cappin ng beam Figurre 10. Longitu udinal displacement versu us time curvee of bridge sttructures whiile earthquak ke occurs along a the bridg ge Dynamic Peerformance of o the Girderr Bridge undder Composiite Effect Th he simulated d blast load d that is app plied to the bridge struucture when longitudinaal seism mic responsee of main girder g arrivees at the maaximum vallue causes iinstantaneouus effecct to the acceleration ressponse on diifferent partt of the briddge. The oveerall dynamic respo onse of the structure is more intensse comparinng with the only earthquuake loadingg cond dition (see Figure F 11(a))). When im mpact load exerts, the end of the main girdeer boun nces and thee friction beetween main n beam and capping beeam is reducced. A largeer relatiive displaceement appeaars (see Fig gure 11(b)).. In NFBS,, beam falliing is beingg observed under composite action. How wever, in C CFBS, the rrelative dispplacement iis limitted effectively by the caable-sliding friction f bearring for the hhelp of cablees and girdeer does not fall from m the cappin ng beam so that the norm mal functionn of bearingg and beam iis guaraanteed.  (a)Acceleration versus v time cu urve of main (b) Displaacement versu us time curve of main girdeer at th he mid-span girder betw ween beam an nd capping beeam Figurre 11. Time-history curve off bridge structtures under coomposite effecct © ASCE Structures Congress 2017 CONCLUSIONS Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/05/19. Copyright ASCE. For personal use only; all rights reserved. Based on the theory of structural dynamics, this paper presents various methods including numerical simulation and experimental test to explore the performance of girder bridges subjected to blast load and earthquake. Cable-sliding friction bearing is put forward to be used so as to improve the safety of bridges, and simplified scale model is established to verify the applicability of the “Cable-sliding Friction Bearing System”. Two seismic waves- Trinidad and EL Centro combing with blast load (450kg TNT) occurring at various time spots are applied to the girder bridge. After summarizing the numerical simulation results, useful findings show that little influence is made to the damage condition of main girders under composite action compared with only blast load condition. However, the longitudinal displacement will increase because of the vertical rebound of main girders. The increase would be more apparent and series of disasters such as beam falling would occur especially when blast appears at the time that the seismic response arrives at the maximum value. Effective displacement limitation devices should be adopted. In the situation, cable-sliding friction bearing is an ideal choice to make with the extra help of cables comparing with ordinary bearing. In scale model test, two different damping bearing systems are tested including cable-sliding friction bearing system and non-cable friction bearing system. And three different kinds of loading conditions are conducted. From the results, it is found that the cable-sliding friction bearing has good adaptability to seismic effects at different level. Increasing cables does not affect the good shock-absorption performance of the original bearing. In addition, it works well in reducing the vertical and longitudinal displacement response and could dramatically limit the relative displacement between main girder and capping beam, therefore solving the problem of beam falling effectively. However, the more quantitative result could not be given at this stage and is one of the subjects of further studies by authors. ACKNOWLEDGEMENTS The work presented in this paper is jointly sponsored by State Key Laboratory of Disaster Reduction in Civil Engineering Project (No.SLDRCE14-B-14), the National Natural Science Foundation of China (No.51478339, 51278376 and 91315301), National Science and Technology Support Program (No.2015BAK17B04) and Science and Technology Program of Jiangxi Province (No.20151BBG70064). REFERENCES Fujikura S, Bruneau M, Lopez-Garcia D (2008). Experimental investigation of multi-hazard resistant bridge piers having concrete-filled steel tube under blast loading. Journal of Bridge Engineering, 13(6): 586-594. Fouché P, Bruneau M, Chiarito V, et al. (2013). Blast and Earthquake Resistant Bridge Pier Concept: Retrofit and Alternative Design Options. Structures Congress. ASCE, 2013: 216-225. George C. Lee, Zach Liang, J. Jerry Shen, et al. (2011). Extreme Load Combinations: A Survey of State Bridge Engineers. MCEER Publications: Technical Report MCEER -11-0007, Buffalo, New York. © ASCE 13