With a own simple example i have made a dynamic run with one spectrum X.
Restraints are :
Node 10 Anchor
Node 50 X-Stop
Node 60 Z- Stop (Vertical)
Node 70 Anchor
Nodes 50,60,70 in a higher floor Z > as Z node 10.
First calculation a Single Response Analysis.
That mean all restraints becomes the same spectrum X.

Input in Spectrum Load Case 1 :

Spectrum Factor Dir. Start Node Stop Node Incr.
X 1 X

Result: max DX = 1.47 mm


Input in Spectrum Load Case 2 :
Spectrum Factor Dir. Start Node Stop Node Incr.
X 1 X 10 10 1
X 1 X 50 50 1
X 1 X 70 70 1

Result: max DX = 3.59 mm
Questions :
1. For a single response analysis are the input in load
case 1 without start/stop nodes correct ?
2. Is the input in load case 2 likewise load case 1 ?
Why then different DX results ?

The backround my question is :
For a Multi Response Analysis a have different floors with different spectrums (X at node 10; X with Factor 1.5 at node 50,70).
Example :
Floor 1 Anchor Node 10
Floor 2 Anchor Node 70
X Stop Node 50


Now i have also here 2 possibiltys

Input in Spectrum Load case 3
Spectrum Factor Dir. Start Node Stop Node Incr.
X 1 X 10 10 1
X 1.5 X 50 70 20
Result: max DX = 3.79 mm


or :
Input in Spectrum Load case 4
Spectrum Factor Dir. Start Node Stop Node Incr.
X 1 X 10 10 1
X 1.5 X 50 50 1
X 1.5 X 70 70 1
Result: max DX = 4.92 mm

Here also different results ( same node).
Sometimes the restraint node numbers 123 , 167, 189, 193.
(Floor 1) what input correct ?

A.) Start node 123; Stop node 193 ; increment 1 (one line)
B.) or every node one line ?

The are different results !!!