assessment and alternative solutions using sap 200

8/6/2019 Assessment and Alternative Solutions Using SAP 200

1/22

Coursework1 Assessment and Alternative Solutions Using SAP 2000

1

1.Project Brief

Theeight storey structure which was originally builtin Berlin, Germany,is now intendedtohave a replica in Thessaloniki, Greece with the same material and forms of constructions.

However, it is important to note that the characteristics of both sites are quite different in

terms ofthe structureto seismicresponse.The existing structure is a standard occupancy steel framed building, constructed of British

steel sections.Beams all floors UB 203mmx133mmx25kgColumns: Floors 1-4 UC 356mmx368mmx 177kg

Floors 5-8 UC 254mmx254mmx73kg All the beamconnections inthe structure arepinned, as thecolumns intheexistingdesign are

sufficienttocarrytheonly lateral load, wind loads.However, the characteristics of the new site in Thessaloniki, Greece are different from thecharacteristics ofthe site wheretheexisting structureis builtin Berlin, Germany.Thecharacteristics ofthenew siteinThessaloniki, Greece are:

Stiff soil with a shear with a shearwave velocityof 250m/sec Nearest seismic sourceis 22.5km fromthe site The fault is capable ofproducing a large magnitude event and high rate of seismic

activityThe main andpredictable horizontal forcethat is exerted on buildings designed and built in

Germany is wind load, which is very lighter in contrast to the unpredictable lateral forces

induced byearthquakein Greece.Therefore the evaluation is based on whether the existing structure could withstand the

seismic forces that couldoccur inThessaloniki, Greece and the limitations on the total roof

deflection that has been set to 500mm, due to neighbouring buildings. In addition, the inter

storeydrifts shouldnotexceed 2%.Two alternative solutions tothe structurehave beendeveloped sothatthe structure would be

ableto withstand forces that aregenerated fromtheearthquakeduetothenew location.


2/22


2

2.Original Structure Assessment

2.1.

R

esponse Spectrum

Basedonthecharacteristics Thessaloniki, Greece,the seismiccoefficients are:Ca=0.44 andCv=0.64

Using UBC97; 5% dampingelasticresponse spectrum,the functional graphis as shownin

figure 1.

Figure 1: Response spectrum functiondefinition

2.2.Analysis & Result

Theoriginal structureis assessed basedon whetheritcould withstandthe seismic forces that

couldoccurinThessaloniki, Greece. The limitations onthetotal roofdeflectionhas been setto 500mm andtheinterstoreydrifts shouldnotexceed 2%.

The SAP 2000 analysis shows that the structure exhibits high storey drifts and excessive

lateral deflectionparticularlyonthe 8th storeyroof whichis muchmore abovethe limitations

(see figures 6 & 7). This is becausethe structural framehas low stiffness toresistthemoment

duetothe seismic forces.

A few screenshots ofSAP 2000 analysis result of deformed shapes areprovided below on

figures 3,4,5,6 and 7. Alsotheundeformed shapeofthe structure beforethe analysis is shownon figure 2.


3/22

C w

t lt ti l ti i

3

Fi ! " 2: Undeformed shape Fi re 3: Deformed shape (Modal # @ Mode 1

Fi

re 4: Deformed shape (Modal#

@ Mode 4 Fi

re 5: Deformed shape (Modal#

@ Mode 9


4/22

C$ % & ' ( w$ &)

0 Assessmentand Alternati1 e Sol% tions Using SAP 2000

4

Fi2

3

re 6: Deformed shape (Combined) Fi2

3

re 7: Deformed shape (Combined)

3.Al iv l i 1

3.1.Modi i ion

To attain the limitations on the total roof deflection of 500mm and a 2% maximum inter

storey drifts, provision of adequate stiffness to the ori inal structure is very necessary.

tiffening the structure can be achieved either by bracing techniques or introducing a shearwallto the structure.

The first alternative provided here is by introducing diagonal bracings ofCHS 168.3 x 10 into five critical locations on external faces ofthe structure. Patterns of the bracing with theirlocations in the structure are shown on figures 8, 9, 10, 11, and 12.


5/22

Coursework1 Assessmentand Alternati4 e Solutions Using SAP 2000

5

Figure 8:Bracing 1

Figure 9:Bracing 2

Figure 10:Bracing 3


6/22


6

Figure 11:Bracing 4

Figure 12:Bracing 5

3. . Resul s

The analysis proves that the new bracing elements introduced to the original structure give

the building adequate stiffness. The analysis result shows thatthe maximum lateral deflection

in this modification is only 381mm and the inter storey driftis below 2%.

Figures below show the deformed shapes for modal and combined. Deflections at critical

points are also shown in the deformed shapes (combined) screenshots.


7/22


8/22


8

4.Al ernative Solution 2

4.1.Modi i ation

The Second alternative proposed here is by providing a 200mm thick concrete shear wall in

three critical locations pluse introducing diagonal bracings of CHS 168.3 x 10 in to one

location on external faces of the structure. The locations of the shear walls and bracing are

shown below on figure 19.

Figure 19: Arrangement of shear walls & bracings

Shear wall

Shear wallShear wall

Bracings


9/22


9

4.2.Results

The analysis proves thatthenew concrete shear walls and bracingelements introducedtotheoriginal structure give the building adequate stiffness. The analysis result shows that the

maximum lateral deflection in this modification is only 283mm and the inter storey drift isbelow 2%.

Figures below show the deformed shapes for modal and combined. Deflections at critical

points are also showninthedeformed shapes (combined) screenshots.

Figure20: Deformed shape (modal @ mode 1) Figure21: Deformed shape (Combined)

Figure22: Deformed shape (Combined) Figure23: Deformed shape (Combined)


10/22


10

Figure24: Deformed shape (Combined)


11/22


11

Appendix 1

Table 1: Joint Displacements for Alternati e solution 1Joint OutputCase CaseType StepType U1 U2 U3 R1 R2 R3

mm mm mm Radians Radians Radians

1 COMB1 Combination Max 381.947636 344.204580 34.127140 0.011930 0.009425 0.010213

1 COMB1 Combination Min -381.947636 -344.204580 -34.127140 -0.011930 -0.009425 -0.010213




3 COMB1 Combination Min -363.922113 -293.669367 -34.693103 -0.009637 -0.007991 0.000000


























16 COMB1 Combination Min -311.036479 -304.549075 -25.515859 -0.011971 -0.008168 -0.00527717 COMB1 Combination Max 310.697087 223.478098 31.724369 0.009586 0.008208 0.000000


























12/22


12































































13/22


13





















































84 COMB1 Combination Min -120.244690 -82.813797 -0.301062 -0.013060 -0.021367 0.00000085 COMB1 Combination Max 94.951315 81.497569 14.896879 0.011934 0.016424 0.002370










14/22


14























99 COMB1 Combination Min 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000






























114 COMB1 Combination Min 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000115 COMB1 Combination Max 248.972917 90.892513 1.576571 0.004261 0.015204 0.005122










15/22


15




















































144 COMB1 Co mbination Max 95.057686 71.344848 2.457118 0.010070 0.016031 0.002335











16/22


16





















17/22


17

Appendix 2




























































18/22


18































































19/22


19





















































84 COMB1 Combination Min -83.771855 -21.705913 -0.295169 -0.004515 -0.016415 0.00000085 COMB1 Combination Max 31.167669 21.484043 12.086824 0.004178 0.006305 0.003287










20/22


20





















































114 COMB1 Combination Min 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000115 COMB1 Combination Max 172.068393 218.707564 1.496101 0.015662 0.012637 0.008613










21/22


21































































22/22


22
















assessment and alternative solutions using sap 200

Documents