Menggambarkan cara-cara pembuatan kurva respon spektum

gempa rencana

Elastic design response spectra are extremely useful to structural engineers. These spectra are the basis for:— Computing design displacements and forces in systems expected to remain elastic― Developing design forces and displacement systems that respond inelastically by:

─ Modifying elastic spectrum─ Evaluating response of equivalent elastic structure

These elastic spectra can be obtained by several methods, which are:

—Processing of site specific ground motion time histories—Statistical relationships —Empirical relationships —Code stipulations

Elastic spectra can be presented in several formats, depending on the needs of the engineer and what information is being presented. Some of the most common formats are:•Spectral acceleration vs. period •Spectral velocity vs. period •Spectral displacement vs. period •Spectral acceleration vs. spectral displacement (capacity design spectrum) •Tripartite plots (Sa, Sv, and Sd vs. period)

EL-Centro NS 1940

-3.00E-01

-2.00E-01

-1.00E-01

0.00E+00

1.00E-01

2.00E-01

3.00E-01

4.00E-01

0.00E+00 1.00E+01 2.00E+01 3.00E+01 4.00E+01 5.00E+01 6.00E+01

t (detik)

perc

epat

an g

mpa

(cm

/det

2)

Model Matematik

nn

n

gnn

g

Tmk

txxxxtxmkxxcxm

2

)(2)(

2

)(*)()(*)(

)(sin**)(1)(

:matematik model dari Solusi

2

0

)(

txtxtxtx

dtextx

nnDn

nnDn

t

nDtnn

gnD

n

nnnnn

nnnnn

nnnnn

TtxTxTtxTxTtxTx

,,(max),(,,(max),(,,(max),(

Respon Maksimum

Penyelesaian terhadap persamaan INTEGRAL dapat dilakukan dengan beberapa metode:

— Integrasi Duhamel (linier)

— Average Acceleration (kasus linier & non-linier)

— Linear Acceleration (kasus linier & non-linier)

Sember: kuliah Dinamika Struktur

- mulai dari struktur sangat kaku sampai dengan struktur sangat fleksibel biasanya T= 0.01 s/d T=50 dtik- analisis perpidahan, kecepatan dan percepatan untuk masing-masing mode- respon maksimum pad masing-masing mode diambil nilai mutlaknya

EL-Centro NS 1940

-3.00E-01

-2.00E-01

-1.00E-01

0.00E+00

1.00E-01

2.00E-01

3.00E-01

4.00E-01

0.00E+00 1.00E+01 2.00E+01 3.00E+01 4.00E+01 5.00E+01 6.00E+01

t (detik)

perc

epat

an g

mpa

(cm

/det

2)

%55.0

nn dtikT

)(*)()(*)(

)(sin**)(1)(

2

0

)(

txtxtxtx

dtextx

nnDn

nnDn

t

nDtnn

gnD

n

Sadan Sv, Sd, :dengan dikenal masing-masingberikut kuva ketiga dalam atas di masikumRespon

),,(x di terjayang maksimum percepatandan kecepatan,

n,perpindahakan menggambar yang maksimum, respon terdapat respon,riwayat setiap Pada 2.

berikutgambar -gambar pada ditunjukan ersebut bangunan t dari percepatandan

kecepatan n,perpindaharespon Riwayat 1. :diperoleh maka 5% dampingdan

detik, 0.5 (T)getar periodedengan bangunan padadikenakan atas di Centro-El gemparekaman Jika

5.05.00.5 xx

Respon Perpindahan

-10

-8

-6

-4

-2

0

2

4

6

8

10

0 10 20 30 40 50 60

waktu (det)

perp

inda

han

(cm

)

respon perpindahan maksimumuntuk T=0.5 detSd = X-max

Respon Pseudo Kecepatan

-150

-100

-50

0

50

100

150

0 10 20 30 40 50 60

Waktu (detik)

kece

pata

n (c

m/d

et)

respon kecepatan maksimumuntuk T=0.5 detikSv = X'-max

Respon Pseudo Percepatan

-2000

-1500

-1000

-500

0

500

1000

1500

0 10 20 30 40 50 60

waktu (detik)

perc

epat

an (c

m/d

et-2

)

percepatan maksimumSa = X"-max untuk T=0.5 det

1. Tentukan respon riwayat waktu dari setiap mode2. Tentukan respon maksimum (Sa-max, Sv-max, Sd-

max) dari stiap mode3. Gambarkan kurva yang menghubungakan :

1. Sd-max dengan T2. Sv-max dengan T3. Sa-max dengan T

1. Tentukan respon perpindahan maksimum dari setiap mode

2. Ambil nilai mutlaknya

3. Gambarkan specktra respon perpindah (sb-x periode getarnya dan sb-y perpindahannya

1. Tentukan respon kecpatan maksimum dari setiap mode

2. Ambil nilai mutlaknya

3. Gambarkan specktra respon perpindah (sb-x periode getarnya dan sb-y kecepatan

2det/13.1421 2det/ 5.559

det5.0 padapecepatan 5.0

cminchxT

T

1. Tentukan respon percepatan maksimum dari setiap mode

2. Ambil nilai mutlaknya

3. Gambarkan specktra respon perpindah (sb-x periode getarnya dan sb-y percepatan

010

020

030

040

050

060

0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Pseu

do A

ccele

ratio

n, PS

a

Relative Displacement, Sd

Elastic Spectra, Set 1, Direction 1

Damping

5.e-002

Bispec

0.1

1

10

100

1000

0.01 0.1 1 10 100

1. Ketiga kurva di atas menggambarkan spektra respon perpindahan, kecpatan dan percepatan.

2. Kurva tersebut dihasilkan oleh rekaman gempa tertentu dan dengan damping tertentu (5%). Dengan kata lain untuk gempa yang lain dan atau damping yang berbeda, spektranya akan berbeda pula

3. Jika suatu bangunan terkena gempa tersebut, dan bangunan tersebut memiliki damping 5% maka deformasi, percepatan dan kecepatan gerak dari bangunan dapat ditentukan

4. Spektra respon yang dihasilkan sangat bergerigi, perbedaan periode getar (T) yang sangat kecil sekalipun dapat memberikan hasil (respon) yang berbeda secara ekstrim.

1. Untuk penggunaan yang lebih luas, diperlukan pemahaman mengenai karakteristik spektrum respon gempa.

2. Dalam kasus berikut gempa El-Centro N-S 1940 dijadikan sebagai model

0.1

110

100

1000

0.01 0.1 1 10 100

Pseu

do V

eloc

ity, P

Sv

Period

Elastic Spectra, Set 1, Direction 1

Damping

0.2.e-0025.e-0020.10.5

Bispec

- Semakin besar damping,semakin kecil respon struktur.- Semakin besar damping,semakin smooth respon struktur- Respon struktur mengalamipembesaran secara berarti padastruktur dengan periode tengahantar T=0.03 detik sampai denganT<10 detik

Constanvelocity

0.1

110

100

1000

1000

0

0.01 0.1 1 10 100

Pseu

do A

ccel

erat

ion,

PSa

Period

Elastic Spectra, Set 1, Direction 1

Damping

0.2.e-0025.e-0020.10.5

Bispec

- Semakin besar damping,semakin kecil respon struktur.- Semakin besar damping,semakin smooth respon struktur- Respon struktur mengalamipembesaran secara berarti padastruktur dengan periode tengahantar T=0.03 detik sampai denganT<10 detik

Constanacceleration

0.00

010.

001

0.01

0.1

110

100

0.01 0.1 1 10 100

Rela

tive

Disp

lace

men

t, Sd

Period

Elastic Spectra, Set 1, Direction 1

Damping

0.2.e-0025.e-0020.10.5

Bispec

- Semakin besar damping,semakin kecil respon struktur.- Semakin besar damping,semakin smooth respon struktur- Respon struktur mengalamipembesaran secara berarti padastruktur dengan periode tengahantar T=0.03 detik sampai denganT<10 detik

Constandisplacemant

:ndisimpulkadapat Centro-El gempa terhadappengamatan Dari

(1)(PGA) tanah muka

percepatan nilai mendekati nilainyadan konstan sistem percepatanrespon 0.03detik T pada

(2)

(3)

(PGD) tanah mukan perpindaha nilai mendekati nilainyadan konstan sistemn perpindaha

respon detik) 10besar(sangat yang T pada

.fluktuatip mengalami percepatandan kecepatan, n,perpindaha

respon baik nilaidetik 10T0.03untuk

1. Menggambarkan hungan antara Sa, Sv, Sd secara lebih jelas

2. Alat untuk ekplorasi penggunaan respon spektrum

)(*)()(*)(

)(sin**)(1)(

2

0

)(

txtxtxtx

dtextx

nnDn

nnDn

t

nDtnn

gnD

n

ionAmplificatRespon

0

0

0

gMAXn

a

gMAXn

v

gMAXn

d

xxR

xxR

xxR

avd RRR ,,Hubungan

dn

v

n

a RRR

Log skala dalam dan ,Hubungan dv RR

dn

v RR logloglog

Log skala dalam dan ,Hubungan av RR

an

v RR logloglog

Log) (skalaPaper Graph Logarithic dalamndigambarka dan , ,Hubungan dav RRR

Diketahui bahwa antara Sa, Sv dan Sdmemiliki hungan khusus sebagaiberikut:

SdT

SvSaT

SvSvSa

n

n

22

atau

Dengan demikian dapat dibuat satukuva yang menggambarkanSa(pecepatan), Sv(kecepatan) danSd(perpindahan) dlam satu kurva, dimana absisnya adalah Tn atau fn

Kurva ini menunjukan spktrumrespon gempa elcento yangdiplot dalam kuva TRIPARTI,serta dihubungkan denganx”(g)0, X’(g)0, dan x(g)0

Jika dibuat normalisasi akan terlihat besar amplifikasi perepatan, kecepan dan perpindah struktur

Kuva ini menunjukan:

1. Respon spektra gempa El-centro dengan damping 5%

2. Zona-zona senitip

3. Respon dalam kurva tripartit lebih smooth dan dapat dibuat garis pendkanan

4. Kurva pendekatan adalah : awal-a, a-b, b-c, c-d, d-e, e-f, dan f-seterusnya

— Bagaimana menentukan titik: (a), (b), (c), (d), (e), dan (f)— Dipelajari lebih lanjut melalui studi atas repon dari berbagai rekaman gempa— Ahli-ahli yang melakukan studi ini antara lain: Newmrk, Bolt, Hall, dll

Response spectra for actual ground motions are quite irregular, as shown below. Do not use them for design — they can be used for analysis to assess the response to a particular earthquake.

Walaupun informasi initidak dapat atau tidaklazim digunakan untukmendisain struktu,namun informasi initetap penting untukmemperkirakan responstruktur tertentu bilaterkena beban gempatertentu.

1. Pilih sejumlah rekaman gempa (karakteristik sama)2. Buat respon spektrum masing-2 rekaman gempa3. Evaluasi standar deviasi (StaDev) pada masing-2 Tn4. Tentukan respon spectrum: nilai MEAN, atau MEAN + 1SD5. Kuva yang dihasilkan lebih smooth

• The general procedure for generating statistically derived spectra is as follows:

• Classes of ground motions are selected (based on soil, magnitude, distance, etc.)

• Response spectra for a large number of corresponding ground motions are generated and averaged

• Curves are fit to match computed mean spectra• Resulting equations are used to develop a design

response spectrum with desired probability of exceedence

Elastic design response spectra can be predicted in the same statistical manner as ground motion parameters such as peak ground acceleration or velocity. Numerous researchers have developed attenuation relationships for elastic spectra.

Where site specific ground motions have been compiled, the response spectra for each record can be averaged. The resulting "mean" spectrum will be smooth. The COE can be used to establish a spectrum with a desired probability of exceedance.

020

040

060

080

010

0012

0014

00

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Pseu

do A

ccel

erat

ion,

PSa

Period

Elastic Spectra, All Earthquakes, Direction 1

Damping

5.e-0025.e-0025.e-0025.e-0025.e-002

Bispec REKAMAN GEMPA1. El Centro NS 19402. Landers 19923. Loma Prieta 19894. Northridge 19945. Kobe Jepang 1995

010

2030

4050

6070

8090

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Pseu

do V

eloc

ity, P

Sv

Period

Elastic Spectra, All Earthquakes, Direction 1

Damping

5.e-0025.e-0025.e-0025.e-0025.e-002

Bispec REKAMAN GEMPA1. El Centro NS 19402. Landers 19923. Loma Prieta 19894. Northridge 19945. Kobe Jepang 1995

010

2030

4050

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Rela

tive

Disp

lace

men

t, Sd

Period

Elastic Spectra, All Earthquakes, Direction 1

Damping

5.e-0025.e-0025.e-0025.e-0025.e-002

Bispec REKAMAN GEMPA1. El Centro NS 19402. Landers 19923. Loma Prieta 19894. Northridge 19945. Kobe Jepang 1995

0.1

110

100

0.01 0.1 1 10 100

Pseu

do V

eloc

ity, P

Sv

Period

Elastic Spectra, All Earthquakes, Direction 1

Damping

5.e-0025.e-0025.e-0025.e-0025.e-002

Bispec REKAMAN GEMPA1. El Centro NS 19402. Landers 19923. Loma Prieta 19894. Northridge 19945. Kobe Jepang 1995

0.1

110

100

0.01 0.1 1 10 100

Pseu

do V

eloc

ity, P

Sv

Period

Elastic Spectra, Std Dev, Direction 1

Damping

5.e-002

Bispec

0.1

1

0.01 0.1 1 10 100

Pseu

do V

eloc

ity, P

Sv

Period

Elastic Spectra, COV, Direction 1

Damping

5.e-002

Bispec

0.1

110

100

0.01 0.1 1 10 100

Pseu

do V

eloc

ity, P

Sv

Period

Elastic Spectra, Mean, Direction 1

Damping

5.e-002

Bispec

0.1

110

100

0.01 0.1 1 10 100

Pseu

do V

eloc

ity, P

Sv

Period

Elastic Spectra, Mean + std dev, Direction 1

Damping

5.e-002

Bispec

(1)

(2)

The complexity of the previous methods, and the limited number of records available two decades ago,

led many investigators to develop empirical methods for developing

design spectrum from estimates of peak or effective ground motion

parameters. These relationships are based on the concept that all spectra have a characteristic shape, which is

shown below.

AMPLIFIKASI PERCEPAN

0

0.5

1

1.5

2

2.5

3

3.5

0 1 2 3 4 5 6

T (deti)

ampl

ifika

si (S

a/X"

go)

PGASa

amax

AMPLIFIKASI KECEPATAN

0

0.5

1

1.5

2

2.5

3

0 1 2 3 4 5 6

T (detik)

ampl

ifkas

i kec

epat

an (S

v/X'

g0)

PGVSv

vmax

AMPLIFIKASI PERPINDAHAN

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6

T (detik)

ampl

ifika

si (S

d/Xg

0)

PGDSd

dmax

From observation of the above spectra, it can be seen that the maximum acceleration, velocity, and displacement occur in different period ranges. In addition, the maximum value is usually contained in a region where the spectral values are nearly constant. The spectrum can then be roughly divided into three regions: a region where acceleration is nearly constant, one where velocity is nearly constant, and one where displacement is nearly constant. N. M. Newmark and W. J. Hall developed a particularly simple and useful procedure for applying these basic principles to the development of elastic design spectra, which is explained in detail in the next page.

N. M. Newmark and W. J. Hall's procedure for developing elastic design spectra starts with the peak values of ground acceleration, velocity, and displacement. These values are used to generate a baseline curve that the spectrum will be generated from. The values of peak ground acceleration and velocity should be obtained from a deterministic or probabilistic seismic hazard analysis. The value of peak ground displacement is a bit more difficult to obtain due to the lack of reliable attenuation relationships. Some empirical functions utilizing the PGA are available to provide additional estimates of the peak ground displacement. A typical baseline curve plotted on tripartite axes is shown below.

Berikut ini diuraikan cara menentukan garis BASE-LINE

(a) formulan menggunakadengan ditentukan , nilai lain, yang untuk (c)

36dan sec;/48 ;1 :dengandibentuk dapat Tripatite kuva dalam line base garidemikian dengan (b)

6*

dan sec//48 (a)

:sbbn digambarkadapat yang motion) ground(peak ,, anatrahubungan ada 2.

smooth cenderung tripatitekurva dalamstruktur respon spektrum 1.

:gambarandiperoleh gemparekaman sekumpulan terhadapstatistik Studi

000

00

0

20

0

0

0

000

ggg

gg

g

g

g

g

g

ggg

xxxinxinx

gx

xxx

ginxx

xxx

Hasil studi dari Newmark & Hallmendapatkan base line :

- Sa = 1 g- Sv = 48 inc/det

- Sd = 36 inch

1. Plot pda sb-Sv garis mendatar dengan nilai Sv = 48 in/det2. Plot pada sb-A garis miring ( 450), dengan nilai Sa = 1 g3. Plot pada sb-Sd garis miring ( -450), dengan nilai Sd = 36 in

Newmark and Hall's empirical elastic spectra are easily constructed by hand using the following procedure:

1. Construct ground motion 'backbone' curve using constant agmax, vgmax, dgmax lines. Take lower bound on three curves (solid line on figure).

2. Use response amplification factors (listed in table on next page to determine spectral values in the following period ranges:— Short period (Tn < 0.03 sec) Sa = ag—Transition —Constant amplified acceleration range (Tn > 0.13 sec) Sa = a.ag— Intermediate period range Sv = vvg— Long period range Sd = ddg — Very long period range Sd = dg (transition unclear)

3. Connect the lower bound response lines.

Structural Response Amplification FactorsStructural response amplification factors are then applied to the different period-dependent regions of the baseline curve. These factors differ for acceleration, velocity, and displacement, especially at low values of damping. The factors decrease rapidly with increasing damping, especially at small damping values. These factors are shown in the table below.

Damping(%

critical)

Structural response amplification factors

Median + One Sigma

a v d a v d

1 3.21 2.31 1.82 4.38 3.38 2.732 2.74 2.03 1.63 3.66 2.92 2.423 2.46 1.86 1.52 3.24 2.64 2.245 2.12 1.65 1.39 2.71 2.3 2.017 1.89 1.51 1.29 2.36 2.08 1.8510 1.64 1.37 1.2 1.99 1.84 1.6920 1.17 1.08 1.01 1.26 1.37 1.38

Newmark and Hall's structural response amplification factors can also be used to change the damping value of other spectra, such as those generated using attenuation relationships. This modification technique is presented in the viscous damping section of the notes.

All three types of spectrum (Sa vs. T, Sv vs. T, and Sd vs. T) can be plotted as a single graph, and three spectral values for a particular period can easily be determined. The Sa, Sv, and Sd values for a period of 1 second are shown below.

If desired, plot the spectrum in a different format, such as the one shown here

Perbandingan antara ElCentro NEWMARK & HALL dengan Respon Spektrum MEAN+1SD

0

200

400

600

800

1000

1200

1400

1600

1800

0 1 2 3 4 5

T (detik)

perc

epat

an (c

m/d

et-2

) elcentro-Newmark Hallmean+1SD

RESPON SPECTRUM PSEUDO PERCEPATAN (HASIL ANALITIS) &SPEKTRUM PSEUDO PERCEPATAN ELSATIK (Newmark & Hall)

UNTUK GEMPA ELCENTRO 1940

0

200

400

600

800

1000

1200

1400

1600

0 1 2 3 4 5 6

T (detik)

perc

epat

an (c

m/d

et-2

)

elcentro-Newmark Hallelcentro-RS

respon spektrum gempa El-Centro 1940 hasil analisis (integrasi langkah demi langkah) dengan =5%

respon spektrum pseudo percepatan gempa El-Centro 1940 diperoleh dengan cara pendekatan menurut cara Newmark & Hall

The 1997 NEHRP Recommended Provisions for Seismic Regulations for New Buildings has developed a more detailed procedure for estimating site specific design response spectra. This spectrum, with minor changes, will be incorporated into the year 2000 International Building Code (IBC). This spectrum is based on a maximum considered earthquake (MCE) with a 2% probability of occurence in 50 years (2500 year recurrence interval). Detailed maps, which are based on probabilistic estimates by USGS [1], provide spectral ordinates at periods of 0.2 and 1.0 seconds. These maps are for medium rock sites, but factors to account for soil conditions are included.

However, the IBC implementation of these provisions will be for a single design level event with a probability of 10% in 50 years. Since the code uses a single-level indirect method rather than performance-based engineering, only one level of event is specified. This event is taken to be 2/3 of the MCE event from the NEHRP provisions. For California, this relationship is about right, but for other areas (such as New Madrid) this results in unnecessarily large events. However, lower standards for design (e.g. ordinary moment frames) are permitted in these areas.

The basic form of the spectrum looks like a typical code or Newmark and Hall spectrum. The corner points are:To = 0.2Sd1/SdsTs = Sd1/SdsUse:V = CsWCs = Sds/(R/I) < Sd1/(TR/I)

For soft soils, ag remains the same or decreases relative to firm soil, but vg and dg increase, generally.Layers of soft clay, such as the Young Bay Mud found in the San Francisco Bay area, can also act as a filter, and will amplify motion at the period close to the natural period of the soil deposit.Layers of deep, stiff clay can also have a large effect on site response. For more information on site effects, see Geotechnical Earthquake Engineering by Kramer.

For near-fault motions ag increases, but vg increases more dramatically due to effect of a long period pulse. This pulse is generally most severe in the fault normal direction (as it can cause fling), but significant displacement also occurs in the fault parallel direction. The fault parallel direction usually has much lower spectral acceleration and velocity values than the fault normal direction. Sample waveforms are located in a previous section of the notes, Factors Influencing Motion at a Site. No matter the directivity, however, the motions very close to the fault rupture tend to be more severe than those located at moderate distances.

Somerville et al. have developed a relationship which converts mean spectral values generated from attenuation relationships to either the fault parallel or fault normal component of ground motion. See the Interactive Example for a demonstration of the shift of the spectrum in the long period range.

Viscous damping is a convenient analytical concept to account for general energy dissipation and analytical uncertainties. Viscous damping is usually used to represent the following:

— Friction between and with structural and non-structural elements—Localized yielding due to stress concentrations and residual stresses under low loading and gross yielding under higher loads—Energy radiation through foundation—Aeroelastic damping —Viscous damping —Analytical modeling errors

Viscous Damping Values for DesignMany codes stipulate 5% viscous damping unless a more properly substantiated value can be used. Note that actual damping values for many systems, even at higher levels of excitation are less than 5%.

Since statistically derived spectra have only been generated thus far for 5% viscous damping, it is necessary to modify these spectra if different levels of damping are required. Either Newmark and Hall’s response amplification factors or the FEMA 273 procedure can be used to modify statistically derived spectra or other spectra. Note that these factors are period dependent!

Newmark and Hall's MethodFor each range of the spectrum, the spectral values are multiplied by the ratio of the response amplification factor for the desired level of damping to the response amplification factor for the current level of damping.

Consider if we have a median spectrum at 5% viscous damping and we would like it at x%. If the 5% Joyner and Boore Sv value is 60 cm/sec on the descending branch, an estimate of the 2% Sv value is 60x(2.03/1.65) = change 60x1.47 = 88 cm/sec.

When using the Change Damping function in Modspec, you can use Newmark and Hall's factors as described above. Try it out for any spectrum of your choice in the following Interactive Example.

FEMA 273 ProcedureThe FEMA 273 procedure, which is based on Newmark and Hall's method, operates in a very similar manner, except that there are only two spectral regions of interest -- constant acceleration and constant velocity. The damping value is changed by simply dividing each region by the correct coefficient. The coefficients BS for the constant acceleration region and B1 for the constant velocity region are given in the table below.

Effective Damping (% critical) BS B1

< 2 0.8 0.85 1.0 1.0

10 1.3 1.220 1.8 1.530 2.3 1.740 2.7 1.9

> 50 3.0 2.0

The very large values of effective viscous damping are intended for use with structures utilizing seismic isolation or energy-dissipation technology. If values of damping other than those listed in the table are needed, liner interpolotion should be used between table values.

900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400

00

50

100

100

1

1

1

23

4

5

56

23

4

6

6

6

NTT masuk dalam Zona 4,5, & 6- Zona 4 : Manggarai Utara, Flotim, Alor- Zona 6 : Sebagian besar Sumba- Zona 5 : Sebagian besar NTT

Spektra Respon gempa Indonesia didasarkan pada :

1. Probabilitas 10% untuk umur bangunan 50 th (Periode ulang : 475 thn)

2. Keadaab tanah dibagi dalam 3 kategori:

1. Tanah Lunak

2. Tanah sedang

3. Tanah Lunak

3. Damping dianggap 5%

4. Untuk nilai damping yang lain dapat dimodifikasi sesuai dengan rekomendasi FEMA atau mengguakan Metode Newmark & Hall

JENIS TANAHKECEPATAN RAMBAT

GELOMBANG GESER RATA-RATA

HASIL TEST PENETRASISTANDART RATA-RATA

KUAT GESERNIRALIR RATA-RATA

TANAHKERAS

TANAHSEDANG

TANAHLUNAK

TNAHAKHUSUS

det)/(mvs N )(kPaSu

DIPERLUKAN EVALUASI KHUSUS DI SETIAP LOKASI

ATAU SETIAP PROFIL DEANGAN TANAH LUNAK YANG TEBAL TOTALLEBIH DARI 3 M DENGAN PI > 20, We >= 40%, DAN Su < 25 kPa

175sv 15N 50uS

350175 sv 5015 N 10050 uS

350sv 50N 100uS

meter 30kedalaman pada sampai pengeboran hasil tanah datan berdasarka harus tanah Jenis menentukanuntuk

m

isi

i

m

ii

s

vt

t

v

1

1

m

ii

i

m

ii

Nt

t

N

1

1

m

iui

i

m

ii

u

St

t

S

1

11t

2t

3t

4t

m30

uiisi SNv ,,

uiisi SNv ,,

uiisi SNv ,,

uiisi SNv ,,

Log-Bore

anbersangkut tanah jenisuntuk maksimum nilai dari kurang tidakharus nilai respon,pastian ketidak terdapat 0.2T0 - tanahmukapuncak percepatan : mana di , C nilai ,0 - 00

CAAT

cmrr

c

mc

cm

TAATACTT

ACTT

CTAA

: -

: - :berikutpersamaan dengan ditentukan

gempa respons maka lunak,dan sedang keras,h untuk tanamasing-masing det0.1,6.0,5.0untuk 5.2 0

ZONA-1

0

0.05

0.1

0.15

0.2

0.25

0 0.5 1 1.5 2 2.5 3

T (detik)

koef

gem

pa (g

al)

Tanah KerasTanah SedangTanah Lunk

ZONA-2

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.5 1 1.5 2 2.5 3

T (detik)

koef

gem

pa (g

al)

Tanah KerasTanah SedangTanah Lunk

ZONA-3

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.5 1 1.5 2 2.5 3T (detik)

koef

gem

pa (g

al)

Tanah KerasTanah SedangTanah Lunk

ZONA-4

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 0.5 1 1.5 2 2.5 3

T (detik)

koef

gem

pa (g

al)

Tanah KerasTanah SedangTanah Lunk

ZONA-5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5 3

T (detik)

koef

gem

pa (g

al)

Tanah Keras

Tanah Sedang

Tanah Lunk

ZONA-6

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5 3

T (detik)

koef

gem

pa (g

al) Tanah Keras

Tanah SedangTanah Lunk