V. ASCE 7 Mass Irregularity
Verify mass irregularity check in accordance to the ASCE 7-16 specifications.
Details
A three story structure is modelled with floor diaphragms defined at the story levels.
Isometric and Plan View of Structure
Results
| Result Type | Reference | STAAD.Pro | Difference | Comments | |
|---|---|---|---|---|---|
| Diaphragm 1 | Ratio of 1st/2nd floor weights | 0.625 | 0.625 | none | |
| Check | OK | OK | none | ||
| Diaphragm 2 | Ratio of 2nd/3rd floor weights | 0.696 | 0.696 | none | |
| Check | OK | OK | none | ||
| Ratio of 2nd/1st floor weights | 1.6 | 1.6 | none | ||
| Check | Fail | Fail | none | ||
| Diaphragm 3 | Ratio of 3rd/2nd floor weights | 1.438 | 1.437 | negligible | |
| Check | OK | OK | none | ||
STAAD.Pro Input File
The file C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\ Verification Models\06 Loading\IBC\IBC 2018 Mass Irregularity.STD is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 03-Mar-19
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 0 5 0; 3 5 5 0; 4 5 0 0; 5 0 0 5; 6 0 5 5; 7 5 5 5; 8 5 0 5;
9 0 10 0; 10 5 10 0; 11 0 10 5; 12 5 10 5; 13 0 15 0; 14 5 15 0; 15 0 15 5;
16 5 15 5;
MEMBER INCIDENCES
1 1 2; 2 2 3; 3 3 4; 4 2 6; 5 3 7; 6 5 6; 7 6 7; 8 7 8; 9 2 9; 10 3 10;
11 6 11; 12 7 12; 13 9 10; 14 9 11; 15 10 12; 16 11 12; 17 9 13; 18 10 14;
19 11 15; 20 12 16; 21 13 14; 22 13 15; 23 14 16; 24 15 16;
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 2.17185e+07
POISSON 0.17
DENSITY 23.5616
ALPHA 1e-05
DAMP 0.05
TYPE CONCRETE
STRENGTH FCU 27579
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 TO 24 PRIS YD 0.5 ZD 0.5
CONSTANTS
MATERIAL CONCRETE ALL
SUPPORTS
1 4 5 8 FIXED
MEMBER CRACKED
1 3 6 8 TO 12 17 TO 20 REDUCTION RIY 0.7 RIZ 0.7
2 4 5 7 13 TO 16 21 TO 24 REDUCTION RIY 0.35 RIZ 0.35
DEFINE REFERENCE LOADS
LOAD R1 LOADTYPE Mass TITLE REF LOAD CASE 1
JOINT LOAD
2 3 6 7 FY -10
9 TO 12 FY -16
13 TO 16 FY -23
END DEFINE REFERENCE LOADS
FLOOR DIAPHRAGM
DIA 1 TYPE RIG HEI 5
DIA 2 TYPE RIG HEI 10
DIA 3 TYPE RIG HEI 15
*CHECK IRREGULARITIES CODE IS1893 2016
CHECK IRREGULARITIES CODE ASCE7
DEFINE IBC 2018
ZIP 92887 I 1 RX 3 RZ 4 SCLASS 1 TL 8
LOAD 1 LOADTYPE None TITLE STATIC_X
IBC LOAD X 1
LOAD 2 LOADTYPE None TITLE STATIC_Z
IBC LOAD Z 1
PERFORM ANALYSIS PRINT LOAD DATA
PRINT ANALYSIS RESULTS
FINISH
STAAD.Pro Output
-IRREGULARITY CHECKS STAAD.PRO IRREGULARITIES CHECK - ( ASCE7-2016 ) v1.0 ********************************************************* --TORSION IRREGULARITY CHECKS Torsion Irregularity Check Ref: Fig. C12.3-1 T1- Ratio Limit(s): 1.20, 1.40 ------------------------------------------------ Dia. Extreme Points of Dia in X Extreme Points of Dia in Z Node Disp. Node Disp. Node Disp. Node Disp. (mm) (mm) (mm) (mm) ------------------------------------------------------------------------ 1 7 0.24199 2 0.24199 3 0.24199 2 0.24199 2 12 0.85035 9 0.85035 10 0.85035 9 0.85035 3 16 1.62595 13 1.62595 14 1.62595 13 1.62595 Diaphragm D X-max/avg D Z-max/avg Status -------------------------------------- 1 1.0000 1.0000 OK 2 1.0000 1.0000 OK 3 1.0000 1.0000 OK --GEOMETRY IRREGULARITY CHECKS Re-Entrant Corner Check. (Ref: Fig. C12.3-1 T2- Ratio Limit: 0.15 ) ------------------------------------------ ***NOTE: No Irregular Re-Entrant Nodes found in the diaphragm. ***NOTE: No Irregular Re-Entrant Nodes found in the diaphragm. ***NOTE: No Irregular Re-Entrant Nodes found in the diaphragm. --MASS IRREGULARITY CHECKS Mass Irregularity Check Ref: Fig. C12.3-2 T2- Ratio Limit: 1.50 --------------------------------------- Dia. Level Mass Above Below Ratio Ratio Status ( m) ( kN) ( kN) ( kN) Above Below --------------------------------------------------------------------- 1 5.000 40.000 64.000 Base 0.625 N/A OK 2 10.000 64.000 92.000 40.000 0.696 1.600 FAIL 3 15.000 92.000 Top 64.000 N/A 1.437 OK