DEVELOPMENT OF REAL-TIME RESIDUAL SEISMIC CAPACITY EVALUATION SYSTEM -INTEGRAL METHOD AND SHAKING TABLE TEST WITH PLAIN STEEL FRAME-

Transcription

1 13 th World Conference on Earthquake Engneerng Vancouver, B.C., Canada August 1-6, 24 Paper No. 69 DEVEOPENT OF REA-TIE RESIDUA SEISIC CAPACITY EVAUATION SYSTE -INTEGRA ETHOD AND SHAKING TABE TEST WITH PAIN STEE FRAE- Koch KUSUNOKI 1 and asaom TESHIGAWARA 2 SUARY In order to reduce furthermore damage of structures and the number of refugee due to an aftershock, a quck nspecton on the damaged buldngs must be carred out. However, the buldngs have to be nvestgated one by one by engneers or researchers under the present stuaton. The judgement can vary accordng to the engneers experences and t takes long tme to nvestgate all damaged buldngs. Ths research ams to develop a new automatc and quck nspecton system that has only a few cheap accelerometers. Ths system makes t possble to ndcate the safety level of a buldng aganst an aftershock to nhabtants mmedately. The judgement wll be made based on the spectrum method. In ths paper, shakng table test results wth steel frame structures are presented to confrm the valdty of the system. INTRODUCTION Once a bg earthquake occurs, many buldngs are severely damaged, and consequently t gves rse to many homeless. The damage level could ncrease due to an aftershock n some buldngs. Thus enormous harm to the nhabtants n such buldngs could occur. On the contrary, some people could get caught up n fear and would escape from even the buldngs that have enough resdual sesmc capacty from the engneerng pont of vew. Hence, the number of homeless can ncrease drastcally. In order to reduce further damage due to an aftershock and to reduce the number of homeless, a quck nspecton on the damaged buldngs must be carred out soon after a man shock. However, under the present stuaton, the buldngs have to be nvestgated one by one by engneers or researchers. For example, 5,68 engneers and 19 days were needed to nvestgate 46, buldngs on a damaged area at the Kobe earthquake (JBDP [1]). Nneteen days were too long and yet the number of nvestgated buldngs was not enough. oreover, many buldngs were judged as Cauton level, whch needs detaled nvestgaton by engneers. Cauton judgement s a gray zone and t could not take away anxetes from nhabtants. Furthermore, the current quck nvestgaton system presents a dlemma snce buldngs should be nvestgated by vsual observaton of engneers. Thus, ths judgement vares accordng to the engneers experences. 1 Senor Researcher of Buldng Research Insttute, Japan, kusunok@kenken.go.jp 2 Chef Researcher of Buldng Research Insttute, Japan, tesh@kenken.go.jp

2 On the other hand, f t s possble to calculate the performance and demand curve (JBRP [2]) from a measured acceleraton of the basement and of each floor of a structure wth cheap accelerometers, and further estmate the resdual sesmc capacty of a structure by comparng these curves, the problems mentoned above can be solved. To draw the performance curve, the absolute response acceleratons and relatve response dsplacement on each floor are needed. A certan fxture s generally needed to measure the nter-story drft or the relatve response dsplacement to the basement. Ths fxture can be obstructve for usage. On the contrary, t s easy to measure acceleratons wth accelerometers. If dsplacements can be derved from the acceleratons wth double ntegral, the performance curve of structures can be easly measured. In ths paper, a new real-tme resdual sesmc capacty evaluaton system was proposed. Furthermore, shakng table tests wth steel plane frame was carred out to confrm the valdty of the proposed evaluaton system. CONFIGURATION OF THE SYSTE AND OUTINE OF THE EVAUATION Ths system has bascally two accelerometers and one judgement machne as shown n Fg. 1. The evaluaton method s based on the performance desgn concept as shown n Fg. 2. The resdual sesmc capacty wll be judged by comparng the measured performance curve of a structure and the measured demand curve. Accelerometer Accelerometer Judgement machne Fg. 1 Confguraton of the system The performance curve s the relatonshp between the representatve deformaton D and the representatve restorng force S, whch shows the predomnant response of a structure. The method to evaluate theses representatve values s outlned below. The calculated relatve dsplacement vector to the basement { x} derved as Eq. 1 wth the modal partcpaton factor { x} s the unque vbraton mode. { x} = { u} β Eq. 1 from measured acceleratons can be β, mode vector { u}, and the assumpton that the

3 S Shear coef. and Resp. Acc. Sa (kn/ud) Yeldng dampng of 5% Redcton due to damage ax. response Ultmate dsp. Performance curve Horzontal deformaton Sd (m) Fg. 2 Outlne of the evaluaton based on the Performance desgn concept The story shear (nerta force) of the frst story Q B can be calculated usng Eq. 2 wth the measured absolute acceleraton { & x + & x } and mass m of each floor. Q ( x& & x ) m & + Eq. 2 B = The equaton of moton of a mult-degree-of-freedom system can be reduced to a sngle- degree-offreedom system as gven n Eq & C ~ + & K ~ = & : Total mass of a structure C ~ : Equvalent dampng K ~ : Equvalent stffness & x& : Ground acceleraton x The Q B can be calculated wth Eq. 4. If the frst mode s predomnant enough, the calculated angular K ~ frequency, ω =, can be the natural angular frequency of the frst mode. Eq. 3 S= Q = & B Eq. 4 Eq. 5 can be derved from Eq. 1 by devdng both sdes by. The nerta force actng on each floor can be derved as Eq. 6 by usng Eq. 1 and Eq. 5. x β u = Eq. 5 x P = m β u && = m & Eq. 6 P

4 The total mass can also be derved from Eq. 4 and Eq. 6 snce the total mass s the sum of each floor mass,.e.; x m && Q m x B = = = = m && && Therefore, the representatve dsplacement can be derved as Eq. 7. = m m x Eq. 7 The representatve acceleraton, & s appled to the representatve restorng force, S ( S = Q m = & ). If a system s elastc, the representatve dsplacement, and the representatve acceleraton, can be calculated wth Eq. 8,.e.; 2 2 & + 2 h & & ω + ω = x Eq. 8 h : Dampng coeffcent ω : Angular frequency S As a result, the maxmum representatve dsplacement max and the absolute acceleraton ( & + & x& ) max correspond to the value from the response dsplacement and acceleraton spectrum wth a dampng coeffcent of h. On the other hand, the demand curve s the relatonshp between the response acceleraton (Sa) and dsplacement (Sd) spectrum. The ntersecton pont of the demand and performance curve shows the maxmum elastc response. However, the damage of a structure can dsspate some amount of an nput energy, thus the dampng effect can be ncreased. Therefore, the demand curve can be reduced accordng to the damage (Fg. 2). The ntersecton pont of the reduced demand and performance curves shows the maxmum nelastc response. Addtonally, the followng three challengng assumptons were appled for the judgement of the resdual sesmc capacty. These assumptons need further studes. Defnton of aftershock The mechansm of an aftershock s the same as the man shock, and the aftershock s always smaller than the man shock Wth ths assumpton, the demand curve of the aftershock corresponds to the man shock. Substtute dampng rato for aftershock and judgement The dampng coeffcent for the demand curve of an aftershock s 5% In fact, f further damage occurred n a structure durng an aftershock, an addtonal dampng can be acheved, then the demand curve wll be reduced. However, t s dffcult now to estmate accurately the dampng effect due to the damage durng an aftershock. Therefore, the dampng effect due to nelastc behavor durng an aftershock s neglected and 5% vscous dampng s taken nto account for the judgement on the safe sde. The resdual sesmc capacty can be calculated wth the comparson of the demand curve wth 5% dampng and the performance curve. If the rato of the Sa(=Sa p ) at the ultmate

5 dsplacement on the performance curve to the Sa(=Sa d ) on the demand curve s greater than 1., the structure wll be judged as SAFE, and f t s less than 1., t wll be judged as UNSAFE. The restorng force and the vbraton mode wll be constant after the maxmum response s reached and less than the ultmate. If the maxmum response s less than the ultmate dsplacement, the performance curve to the ultmate dsplacement must be extrapolated. The restorng force and the vbraton mode are assumed as constant after the maxmum response reached to the ultmate dsplacement. If a structure s elastc durng a man shock, the performance curve calculated wth the assumpton (3) can be much underestmated snce the restorng force at the ultmate dsplacement can be less than the yeldng strength. Therefore, t must be judged separately f a structure s elastc. The elastc-nelastc judgement method s shown n Fg. 3. Frstly, the approxmated stffness of the envelope curve of the performance curve s calculated. Secondly, the error between the envelope curve and the approxmated lne, Sd ( ), s calculated. If the rato of the maxmum value of, Sd ( ), to the maxmum response, Sd max, s less than a tolerance, t s judged as elastc. In ths study, a 5% tolerance s appled. Approxmated stffness ax. response Sd () Sa (G) Sa-Sd Envelope Sd (cm) Sd max Fg. 3 Elastc-nelastc judgement The judgement flowchart s shown n Fg. 4. The responses of a buldng and an nput earthquake moton are measured by accelerometers, and the resdual sesmc capacty,.e. how large the aftershock can be sustaned by the buldng, s calculated from these measured acceleratons. The safety level aganst an aftershock can be ndcated just soon after a man shock. Ths System has a computer applcaton, whch can calculate the followng tems; Integrate the measured acceleratons twce to calculate the response dsplacements. Calculate the base-shear coeffcent and the representatve dsplacement of the buldng wth an assumed mode shape. (tems 7 & 8 n Fg. 4) Draw the performance curve of the structure. (tem 9 n Fg. 4) Draw the envelope curve of the performance curve. (tem 1 n Fg. 4) Calculate the response spectrum of the measured acceleraton on the basement, and calculate the demand curve. (14 n Fg. 4)

6 Evaluate the resdual sesmc capacty of the buldng by means of the performance and demand curves. easured acceleraton on basement 1 measurem X & j Integraton 2 relatve dsp. m X j 3 Vbraton mode of buldng 4 Calculate Interstory drft C X 5 Calculate Abs. Acc. on each & floor C X& 6 ass rato m ~ 7 Representatve Dsp. Sd m ~ C X Sd = ~ 2 m X C 8 Representatve Acc. Sa = m ~ C X& S a m~ 13 From measured acc. X & m Calculate Resp. Acc. Spectra Ra Resp. Dsp. Spectra Rd 9 Generate Performance Curve 1 Draw envelope curve of 9 11 Ultmate Dsp. Ru 14 Calculate (Ra- Rd Curve) Compare 12 Draw Performance curve untl Ultmate Dsp. 15 Judgement Elastc Safe Danger Input value 16 Indcate judgement Fg. 4 Judgement flow chart Items 3, 6, and 11 n Fg. 4 must be defned pror to makng a judgement. The tem 3 (vbraton mode shape) s to calculate the response acceleratons on the floors where there are no accelerometers. For example, a lnear or a constant dstrbuton shape between measured floors can be appled. The tem 6 (mass rato) can be calculated from floor area rato between each floor. At the moment, tem 11 (ultmate dsplacement) can be defned from the correspondng adopted buldng code.

7 INTEGRATION ETHOD TO CACUATE DISPACEENT FRO ACCEERATION The response dsplacement s derved from measured acceleraton wth double ntegral technque n the proposed evaluaton system. If dsplacement s calculated wth the trapezodal ntegral technque, t can dverge easly. There are two ways to ntegrate acceleraton record, ntegraton n frequency-doman and n tme-doman. The Iwan s method (Iwan [3]) was appled for the system, whch ntegrates n tme-doman. The outlne of Iwan s method s descrbed below. The nose level observed durng a prncpal shock s assumed to be constant. The nose level before and after a prncpal shock are also assumed to be constant but dfferent values. The nose level before a prncpal shock can be calculated as the average of measured acceleraton record untl the prncpal shock starts. At frst, the calculated nose level before the prncpal shock s subtracted from whole measured acceleraton record. Then adjusted acceleraton record s ntegrated to calculate tme hstory of velocty (Fg. 5). The velocty baselne shft after a prncpal shock s calculated wth lnearzaton technque so that the velocty can be zero at enough after the prncpal shock. The velocty baselne shft durng the prncpal shock can be calculated so that the velocty baselne shft due to the nose level can contnue from the prncpal shock doman to after the prncpal shock doman. The measured acceleraton from the shakng table test of the 3-story steel structure, and the ntegrated dsplacement wthout usng the Iwan s method are shown n Fg. 6. The calculated velocty baselne shft by usng Iwan s method mentoned above s shown n Fg. 7, and the acceleraton baselne shft s shown n Fg. 8. It s obvous from Fg. 7that the calculated velocty baselne shft s not approprate. The tmehstory of the adjusted velocty s elbowed durng the prncpal shock, and the calculated dsplacement from the elbowed velocty can nclude much error. It can be the reason why several strong pulses are observed durng the prncpal shock n Fg. 6, and the baselne shft could occur at each pulse because of the non-lnearty of the accelerometers. Because of that, the baselne shft durng the prncpal shock could not be represented by the constant acceleraton. Velocty (kne) 2 15 Velocty due to Nose Before Prncpal shock After prncpal shock Tme (sec) Fg. 5 Iwan s ntegraton method (velocty) Acceleraton (gal) Dsplacement (cm) (1) (2) Tme (sec) Fg. 6 easured acceleraton and the ntegrated dsplacement (3)

8 Velocty (kne) Acceleraton baselne shft (gal) (1) Intal baselne shft (2) (3) Baselne shft Tme (sec) Fg. 7 Velocty wthout ntal acceleraton baselne shft and velocty baselne shft Tme (sec) Fg. 8 Calculated baselne shft Fg. 9 shows the Fourer ampltude of the ntegrated dsplacement from the tme hstory of the elbowed velocty. It can be observed that t contans much low-frequency (long perod) components because of the elbowed shaped velocty. In order to remove the error components n frequency-doman, the proper lower and upper bound frequences ω and ω H must be found automatcally. The proposed method to fnd out ω and ω s descrbed below. H Frstly, the power spectrum of the adjusted velocty wth the Iwan s method s smoothed wth the Parzen s Spectral Wndow (Osak [4]) (Fg. 1). Secondly, the frequences mnω when the Fourer ampltude s a local mnmum are found. Sometmes more than one mnω can be found. Three mnω were shown n Fg. 1. Thrdly, the frequences maxω when the Fourer ampltude s a local maxmum between mnω and mnω +1, and the dfference of the Fourer ampltudes at mnω and maxω, h, can be calculated. The mnω of whch h s the maxmum s appled for the ω. Snce the h 2 was the maxmum n Fg. 1, the ω was calculated as Hz. If the Fourer ampltude at the frst natural frequency s enough greater than the Fourer ampltude at the ω (F 2 n Fg. 1), an approprate ω can be found. If t s not enough greater, a hgher degree functon must be appled to calculate baselne shft durng a prncpal shock. If a measured acceleraton contans no error, the ω s calculated as Hz snce the power spectrum shows monotone ncreasng functon from Hz to the frst natural frequency. The upper bound frequency ω H was defned as 25 Hz snce the frequency characterstc of the accelerometer (frequency bandwdth able to be measured) was from a DC up to 3Hz. Fnally, the Butterworth flter, whch s a knd of band-pass flter, wth ts parameter of 4 (Boore [5]) was appled for the Fourer spectrum of the calculated velocty wth the Iwan s method from ω to ω H. The Fourer spectra wth and wthout the Butterworth flter are shown n Fg. 11. The dsplacement can be calculated from the velocty, whch s nversely Fourer transferred from Fg. 11. The calculated dsplacement of the measured acceleraton shown n Fg. 6 and measured dsplacement durng the shakng table test are shown n Fg. 12. It can be observed that the calculated dsplacement agreed well wth the measured dsplacement. It can be thought to use the band-pass flter for the dsplacement wthout the Iwan s method shown n Fg. 6. However, f the Iwan s method was not appled, the effect of nose can be bg enough so that the

9 component of real vbraton can hde behnd the nose components n the Fourer. In other words, the Iwan s method must be appled to reduce the nose components so that the ω can be clearly observed. The proposed method to fnd out the ω s utlzng the characterstc of the structural vbraton of whch natural frequency can be clearly found n the Fourer spectrum. Therefore, the proposed method has to be used carefully n case of ntegratng a measured ground acceleraton snce t has many and random predomnant frequences Fourer ampltude 6 4 Fourer Ampltude 6 4 h 1 h F Frequency (Hz) Fg. 9 Fourer ampltude of the ntegrated dsplacement (Iwan s method) h 3 ω 2 4 6ω 1 ω 2 =ω Frequency (Hz) Fg. 1 How to fnd the ω Fourer Ampltude Velocty w/ Iwan's method Wth Butterworth Flter Between ω <->ω h Butterworth flter H (ω) H(ω) for Butterworth flter Response dsplacement (mm) Integrated dsplacement easured dsplacement. ω 2 =ω Frequency (Hz) Fg. 11 Comparson of Fourer spectra Tme (sec) Fg. 12 Integrated dsplacement wth band-pass flter and measured dsplacement APPICABIITY WITH THE SHAKING TABE TEST RESUTS Test specmens The specmens were one span plane steel frame structure of whch masses are concentrated to the nodal ponts. Steel plats, of whch wdth was 1mm and thckness was 6mm, were used for columns and beams. The number of story was 1, 2, and 3. The 3-story specmen s shown n Fg. 13. The span length was 1,mm and the story heght was 595mm for the frst story and 6mm for the second and thrd story. The weght at the nodal pont was 19 N.

10 Two dfferent falure modes of specmen, story falure n the frst story and total yeldng falure (both ends of beams and bottom of the frst story columns yeld, referred to as total falure, subsequently) were expected. In order to acheve the expected falure, the low-yeld strength steel (nomnal strength s 1 N/mm 2, referred to as Y1, subsequently) was used for the yeld members, and the ordnal strength steel (nomnal strength s 4 N/mm 2, referred to as SN4, subsequently) was appled for the not-yeld members. The materal test results are lsted n Table 1. The average yeld strength of Y1 was 72.4 N/mm 2, and N/mm 2 for SN4. The lateral strength of each specmen was calculated wth these average strengths lsted n Table 1 based on the prncple of vrtual work. The base shear coeffcent of each specmen s lsted n Table 2. Sngle story had hgh base shear coeffcent of.67. On the other hand, the value for other specmens were relatvely low as not exceedng Case Fg. 13 Test specmen (3-story) Table 1 ateral propertes Yeld stress (N/mm 2 ) Young s module (N/mm 2 ) Yeld Stran ( µ ) Fracture stress (N/mm 2 ) Y Average SN Average Table 2 Base shear coeffcent of each specmen Sngle story 2-story 3-story Story falure Total falure

11 The NS component of the El Centro earthquake record was used for the nput moton. The 5% PGA level of the record was nputted frst. Then the nput level was ncreased by 5% up to the maxmum capacty of the shakng table, 18%. The nput moton s shown n Fg. 14, and the Sa-Sd curve (demand curve) s shown n Fg. 15. The elastc response lne wth natural perod of.5 s also shown n the fgure. Ground acceleraton (m/sec 2 ) Sa (G) T=.5sec Tme (sec) Fg. 14 Input moton (1% amplfcaton) Sd (mm) Fg. 15 Sa-Sd curve for the nput moton (1% amplfcaton) easurement The measurng system s shown n Fg. 16. Each story had an accelerometer on the center of the beam to measure the response acceleraton and to be used for double ntegral to calculate dsplacement. Another accelerometer was also placed on the surface of the shakng table to measure the actually nputted moton. The response dsplacements of each floor and the shakng table were also measured by transducers to confrm the accuracy of the ntegrated dsplacement and of the performance curve wth the ntegrated dsplacement. easurng tower Transducer Specmen Transducer Accelerometer Transducer Transducer Shakng table Fg. 16 easurng system

12 The measurng frequency of 1Hz was appled. The measurement was automatcally started wth the system start trgger of 5 mm/sec 2 (5 gal). If an accelerometer senses acceleraton of more than 5 gal, the measurement system was started. Snce the accelerometer system has a memory, the record from 5 seconds pror to the trggered tme was also stored. Then when the measured acceleraton dd not exceed 5 gal for 1 seconds, the measurement was automatcally stopped and the resdual sesmc capacty evaluaton program was executed. For the evaluaton, the ultmate deformaton angle was assumed as.1%. For the double ntegral, the prncpal nput moton ((2) porton n Fg. 6) was assumed to start when the measured acceleraton exceeds 5 gal, and to end when the measured acceleraton dd not exceeds 5 gal subsequently. Test results and dscussons The performance curve of the 2-story total falure specmen calculated wth ntegrated dsplacement from measured acceleraton and the curve wth measured dsplacement are shown n Fg. 17. The nput level was 5% of the orgnal record. The demand curve calculated from the measured acceleraton on the surface of the shakng table s also supermposed n the fgure. The specmen was judged EASTIC. The strength of the 2-story total falure specmen was calculated as.3 (Table 2). The measured maxmum base shear coeffcent exceeded.3 a lttle bt, however from Fg. 17, t can be seen the specmen s stll elastc or just yelded. The performance curve wth the dsplacement from the measured acceleraton agreed very well wth the curve wth the measured dsplacement Sa (G) Integrated -.4 easured Sd (mm) Fg. 17 Envelope of the Sa-Sd curve (2-story, total falure, 5% nput amplfcaton) Fg. 18 shows the both performance curves of the 3-story story falure specmen. The nput level was the 11% of the orgnal record. The ntegrated maxmum dsplacement was 57mm n the postve drecton. The performance curve wth the ntegrated dsplacement was extended horzontally from the recorded maxmum dsplacement pont to the assumed ultmate dsplacement. The specmen was judged UNSAFE, snce t was evaluated nelastc and the expected ultmate pont was less than the demand curve wth 5% dampng. The rato of the ultmate pont to the demand curve (resdual sesmc capacty rato) was calculated as.836. Ths value shows that the specmen wll survve after the aftershock of whch level s 83.6% of the man shock. Even the specmen was nelastc and response dsplacement was relatvely bg, the performance curve wth dsplacement from measured acceleraton agreed acceptably wth the curve wth measured dsplacement. Fg. 19 shows the response and ntegrated response dsplacement on the top of the specmen. The ntegrated dsplacement from the measured acceleraton agreed very well wth the measured dsplacement.

13 Sa (G) Integrated -.8 easured Sd (mm) Fg. 18 Envelope of the Sa-Sd curve (3-story, story falure, 11% nput amplfcaton) 14 Relatve dsplacement (mm) F Integrated easured Tme (sec) Fg. 19 Relatve dsplacement hstory on the 3 rd floor (3-story, story falure, 11% nput amplfcaton) In order to make a severe damage to the 2-story story falure specmen, the sectonal area of the column was reduced. Fg. 2 shows Sa-Sd curves wth ntegrated and measured dsplacements. The Sa-Sd curve wth ntegrated dsplacement s less than the curve wth measured dsplacement n the negatve drecton. Fg. 21 shows the ntegrated and measured relatve dsplacements to the shakng table on the top of the specmen. It can be seen that large resdual dsplacement occurred n the negatve drecton because of the yeldng. However, the resdual dsplacement could not be seen n the ntegrated dsplacement, snce the band-pass flter s appled durng the ntegraton and the long perod porton s cut off. Although the Sa-Sd curves shown n Fg. 2 are dfferent, the envelope curve of the Sa-Sd curve agreed well as shown n Fg. 22. Snce the evaluaton s carred out wth the performance curve (envelope curve of the Sa-Sd curve), f the yeldng dsplacement and strength are predcted well from the measurement, the accuracy of the evaluaton can be acceptable. Thus, the dfference of the resdual dsplacement can be not effectve to the evaluaton result.

14 Sa (G) Integrated easured Sd (mm) Fg. 2 Sa-Sd curve (2-story, story falure, 18% nput amplfcaton, column secton was reduced) Relatve dsplacement (mm) F Integrated easured Tme (sec) Fg. 21 Relatve dsplacement hstory on the 2 nd floor (2-story, story falure, 18% nput amplfcaton, column secton was reduced) 1..5 Sa (G) Integrated easured Sd (mm) Fg. 22 Envelope of the Sa-Sd curve (2-story, story falure, 18% nput amplfcaton, column secton was reduced)

15 CONCUDING REARKS In order to develop the real-tme resdual sesmc capacty evaluaton system for mprovng the safety aganst an aftershock, the outlne of the evaluaton system, the evaluaton results wth exstng shakng table results. Results obtaned from the nvestgaton can be summarzed as follows; 1. The new resdual sesmc capacty evaluaton method was proposed. 2. The Iwan s ntegraton method cannot remove errors enough for some acceleraton record. However, the band-pass flter can remove the errors, whch cannot be removed wth the Iwan s method. 3. The new ntegraton method wth the algorthm to fnd out the lowermost frequency for the band-pass flter s proposed. 4. Snce the proposed ntegraton method utlzng the characterstc of the structural vbraton n whch predomnant frequences can be found obvously, more attenton must be pad n case of usng the proposed method to ntegrate ground acceleraton. 5. The ntegrated dsplacements from the measured acceleraton at the shakng table test agreed very well wth the measured dsplacements. However, the resdual dsplacement on the shakng table dd not agree well wth the measured dsplacement. 6. The dfference of the resdual dsplacement cannot affect the resdual sesmc capacty evaluaton result done by the proposed system. 7. The envelope of the performance curve calculated wth the ntegrated dsplacement agreed very well wth the measured envelope curve. 8. The valdty of the proposed evaluaton system was demonstrated wth shakng table test results of 1 bay 1 to 3 story steel frame specmens. REFERENCES 1. Buldng Center of Japan (BCJ), Report on the reconnassance commttee on the buldng damages due to the Hanshn-Awaj Great Earthquake Dsaster, Summerzaton -, (n Japanese) 2. Japan Buldng Research Promoton Assocaton (BRPA), Gudelnes for performance evaluaton of renforced concrete buldngs, Ghodo, 2.7 (n Japanese) 3. Iwan, W. D., et al.:some Observatons on Strong-moton Earthquake easurement usng a Dgtal Accelerograph, Bulletn of the Sesmologcal Socety of Amerca, Vol. 75, pp , Osak, Revsed manual for the spectral analyss for eathquake, Kashma-Syuppanka, 1994 (n Japanese) 5. Davd. Boore, Chrstopher D. Stephens, and Wllam B. Joyner, Comments on baselne correcton of dgtal strong-moton data: Examples from the 1999 Hector ne, Calforna, earthquake, BSSA, Vol. 1.3, Koch KUSUNOKI and asaom TESHIGAWARA, A new acceleraton ntegraton method to develop a real-tme resdual sesmc capacty evaluaton system, Journal of structural and constructon engneerng, Archtectural Insttute of Japan, No. 569, pp , 23.7 (n Japanese)