Can I do serviceability and strength check for the same load combination ?

Yes you can do that. You need to create two separate load combinations each comprising of same load cases combined with the same combination factors. Subsequently define two load envelopes and label one of these load combinations as serviceability and other as strength. Henceforth ask for a design using both envelopes in the LOAD LIST ENV command.

An example is provided next

…

LOAD 1 DEAD LOAD

MEMBER LOAD

1 UNI Y -0.75

LOAD 2 LIVE LOAD

MEMBER LOAD

1 UNI Y -0.45

LOAD COMB 3 SERVICE LOAD

1 1.0 2 1.0

LOAD COMB 4 STRENGTH LOAD

1 1.0 2 1.0

PERFORM ANALYSIS

UNIT INCHES KIP

DEFINE ENVELOPE

3 ENVELOPE 1 TYPE SERVICEABILITY

4 ENVELOPE 2 TYPE STRENGTH

END DEFINE ENVELOPE

LOAD LIST ENV 1 2

PARAMETER 1

CODE AISC UNIFIED 2005

METHOD ASD

DFF 240 ALL

FYLD 50 ALL

UNT 140 ALL

UNB 140 ALL

TRACK 1 ALL

CHECK CODE ALL

FINISH

The software would then check the members for deflection considering load combination 3 ( or serviceability load envelope 1 ) and check the members for strength considering load combination 4 ( or strength load envelope 2 ) as part of the same code check.