Structural Analyses of Mobile Service Tower MST at Space Launch Complex 2 West for Delta Rockets At

1
Structural Analyses of Mobile Service Tower
(MST) at Space Launch Complex 2 Westfor Delta
RocketsAt Vandenberg Air Force Base, CA

• by
• James A. Balmer, P.E., Anne D. Cope, PhD
• Reynolds Smith and Hills, Inc.
• Merritt Island, FL
• Jimmy D. Schilling, P.E.
• Space Gateway Support, LLC
• Joint Base Operating Support Contract (JBOSC)
• Cape Canaveral Air Force Station, FL
• June 2006

2
THIS PRESENTATION, FOR MOBILE SERVICE TOWER (MST)
STRUCTURE, WILL INCLUDE

• INTRODUCTION TO DELTA ROCKET LAUNCH COMPLEX AND
  PURPOSE OF THIS EVALUATION
• HISTORY SUMMARY FOR MST STRUCTURE
• PHOTOGRAPHS TO DEFINE STRUCTURAL SYSTEM AND
  STRUCTURAL COMPLEXITY OF MST
• GTSTRUDL STRUCTURAL ANALYSES METHODS, PROCEDURES,
  AND COMMANDS USED
• STRUCTURAL ANALYSES RESULTS
• SUMMARY, CONSLUSIONS, AND RECOMMENDATIONS
• REQUEST FOR SUGGESTIONS FROM OTHER ATTENDEES FOR
  IMPROVEMENTS IN ANALYSES METHODS WE USED

3
THIS PRESENTATION, FOR MOBILE SERVICE TOWER (MST)
STRUCTURE, WILL INCLUDE

• INTRODUCTION TO DELTA ROCKET LAUNCH COMPLEX AND
  PURPOSE OF THIS EVALUATION
• HISTORY SUMMARY FOR MST STRUCTURE
• PHOTOGRAPHS TO DEFINE STRUCTURAL SYSTEM AND
  STRUCTURAL COMPLEXITY OF MST
• GTSTRUDL STRUCTURAL ANALYSES METHODS, PROCEDURES,
  AND COMMANDS USED
• STRUCTURAL ANALYSES RESULTS
• SUMMARY, CONSLUSIONS, AND RECOMMENDATIONS
• REQUEST FOR SUGGESTIONS FROM OTHER ATTENDEES FOR
  IMPROVEMENTS IN ANALYSES METHODS WE USED

4
INTRODUCTION

• DELTA ROCKETS ARE LAUNCHED BY NASA INTO POLAR
  ORBIT FROM VANDENBERG AFB AT SPACE LAUNCH COMPLEX
  2 WEST (SLC-2W).
• EXISTING DELTA ROCKETS WERE FOUND TO BE MORE COST
  EFFECTIVE THAN NEW EVOLVED EXPENDABLE LAUNCH
  VEHICLES (EELV) ROCKTES.

5

• AN ADDITIONAL 10 YEAR SUPPLY OF EXISTING DELTA
  ROCKETS WERE ORDERED.
• THEREFORE, AN ADDITIONAL 10 YEARS OF SERVICE LIFE
  MUST BE PROVIDED BY EXISTING SLC2W FACILITIES.
• MAIN LAUNCH STRUCTURES ARE MST AND FUT.

6

• FIXED UMBILICAL TOWER (FUT) HAS BEEN INSPECTED
  AND EVALUATED STRUCTURALLY USING GTSTRUDL
  STRUCTURAL ANALYSES AND MEMBER CODE CHECKS.
• FOR FUT, ONLY MISSING WELDS AND SAFETY UPGRADES
  REQUIRED REPAIRS / MODIFICATIONS.

7

• THE SCOPE OF THIS PRESENTATION IS LIMITED TO
  EVALUATION OF MST STRUCTURE.
• BUILDING CODE IN EFFECT FOR VANDENBERG AFB, CA
  AREA WAS 1997 UNIFORM BUILDING CODE.
• AISC 1989 ALLOWABLE STRESS DESIGN SPECIFICATION
  WAS USED TO CHECK EXISTING MEMBERS AND TO DESIGN
  NEW MEMBERS.

8

• ORIGINAL MST STRUCTURE WAS DESIGNED AND
  FABRICATED IN THE 1950s. MORE HISTORICAL DETAIL
  WILL BE PRESENTED LATER.
• STRUCTURAL DESIGN METHODS, USED TO RESIST WIND
  AND EARTHQUAKE LOADS IN THE 1950s, WOULD SEEM
  QUITE CRUDE WHEN COMPARED TO METHODS AND
  PROCEDURES USED TODAY.

9

• ALSO, A NEW CLEAN ROOM STRUCTURE WITH ALL
  REQUIRED OPERATIONAL SYSTEMS NEEDED TO BE ADDED
  TO MST.
• IT SEEMED REASONABLE TO EXPECT THAT SEVERAL
  EXISTING MEMBERS WOULD NOT PASS STRUCTURAL STEEL
  CODE CHECKS USING LOADS AND LOAD COMBINATIONS
  SPECIFIED IN CURRENT BUILDING CODES ESPECIALLY
  AFTER NEW CLEAN ROOM LOADS WERE ADDED.

10

• IF SEVERAL STRUCTURAL STEEL MEMBERS FAIL CODE
  CHECKS, HOW COULD A STRUCTURAL ENGINEER GET A
  NON-STRUCTURAL ENGINEERING CLIENT TO UNDERSTAND
  THE SIGNIFICANCE OF THESE RESULTS.
• LAYMEN VISUALIZE STRUCTURAL ANALYSES RESULSTS
  DATA SUCH AS, THE FOLLOWING 262 MEMBERS FAILED
  code checks, MUCH DIFFERENTLY THAN AN
  EXPERIENCED STRUCTURAL ENGINEER WOULD.
• LAYMEN DO NOT PROCESS CODE CHECKS ALL THEY
  COMPREHEND INITIALLY IS MEMBERS FAILED.

11

• WE DECIDED TO SET UP ALL STRUCTURAL ANALYSES
  MODELS SO THAT NONLINEAR PUSHOVER ANALYSES COULD
  BE USED FOR ALL LOAD COMBINATIONS.
• ALTHOUGH WE EXPECTED SEVERAL MEMBERS TO NOT PASS
  CODE CHECKS, WE SAW POTENTIAL FOR NUMBEROUS LOAD
  PATHS TO RESIST LOADS.

12
THIS PRESENTATION, FOR MOBILE SERVICE TOWER (MST)
STRUCTURE, WILL INCLUDE

• INTRODUCTION TO DELTA ROCKET LAUNCH COMPLEX AND
  PURPOSE OF THIS EVALUATION
• HISTORY SUMMARY FOR MST STRUCTURE
• PHOTOGRAPHS TO DEFINE STRUCTURAL SYSTEM AND
  STRUCTURAL COMPLEXITY OF MST
• GTSTRUDL STRUCTURAL ANALYSES METHODS, PROCEDURES,
  AND COMMANDS USED
• STRUCTURAL ANALYSES RESULTS
• SUMMARY, CONSLUSIONS, AND RECOMMENDATIONS
• REQUEST FOR SUGGESTIONS FROM OTHER ATTENDEES FOR
  IMPROVEMENTS IN ANALYSES METHODS WE USED

13
MST History
Bridge Crane

• 1950s jack-up type mobile oil drilling rig was
  modified to create Little Joe II Mobile Service
  Tower at White Sands Missile Range, NM.
• Original rig rotated to a horizontal position for
  travel to a new location.

Vertical Tie Back Wire
Diagonal Tie Back Wire
Two rectangular trussed vertical towers formed
structural backbone. Most truss members are
single angles.
Added vertically movable Service Platform
(typical)
Counterweight
14
MST History Contd

• Relocated in 1970s to Vandenberg, CA
• Mounted to rail system
• Cladding, extensive external bracing, fixed
  platforms were added
• Larger guy cables were added for both crane loads
  and gravity loads.
• Much heavier counterweight was added
• Structure was raised by adding a new truss base

15

• In 1990s, MST was jacked up and increased in
  height by adding a prefabricated structural system

16
1990s Jacking
17
1990s Jacking
18
THIS PRESENTATION, FOR MOBILE SERVICE TOWER (MST)
STRUCTURE, WILL INCLUDE

• INTRODUCTION TO DELTA ROCKET LAUNCH COMPLEX AND
  PURPOSE OF THIS EVALUATION
• HISTORY SUMMARY FOR MST STRUCTURE
• PHOTOGRAPHS TO DEFINE STRUCTURAL SYSTEM AND
  STRUCTURAL COMPLEXITY OF MST
• GTSTRUDL STRUCTURAL ANALYSES METHODS, PROCEDURES,
  AND COMMANDS USED
• STRUCTURAL ANALYSES RESULTS
• SUMMARY, CONSLUSIONS, AND RECOMMENDATIONS
• REQUEST FOR SUGGESTIONS FROM OTHER ATTENDEES FOR
  IMPROVEMENTS IN ANALYSES METHODS WE USED

19
MST Rails, Trucks, and Wheels, Forward/Side
Tie-Down Anchor Point
Trucks, Wheels, and Rails
Anchor Point
20
MST Rear Tie-Down, Counterweights, and Rear
Trucks/Wheels
Counterweights
Tie-Down
Wheels
21
MST Exterior
1970s side framing with bridge crane (top left)
MST doors
22
MST elevation looking NW
23
MST Elevation Looking West
Fixed Umbilical Tower (FUT)
Launch vehicle mount
24
MST East Side Looking North
External 1970s side framing
25
MST External 1970s Side Framing
26
One of 2 original single angle trussed
rectangular towers
27
One of 2 original single angle trussed
rectangular towers new diagonal wire rope cable
28
Typical interior service platform framing
29
Typical interior service platform framing
30
Typical interior service platform framing
31
MST View of Top Framing
Bridge crane shelter
Rolled back clean room ceiling
32
Top framing bridge crane girder
33
MST View of Top Framing
Bridge crane
Movable clean room ceiling supports
Cables Vertical Diagonal
34
Bridge crane inside shelter
35
Bridge crane inside shelter
36
Bridge crane support framing crane girder
37
Slight congestion of structural members and
connections
38
Missing and cut structural members
39
Connection of several pipe structural members
Corrosion damage
40
Corrosion Concerns
41
Corrosion Concerns
42
Corrosion Concerns
43
Corrosion Concerns
44

• CCAFS, FL HAS ONE OF THE MOST CORROSIVE
  ENVIRONMENTS THAT HAS BEEN TESTED AND DOCUMENTED.
• BASED ON PAST EXPERIENCE WITH SIMILAR STEEL
  STRUCTURES AT CCAFS, WE EXPECTED TO HAVE TO
  REPLACE A LARGE PERCENTAGE OF EXISTING MEMBERS
  AND CONNECTIONS AT THE VANDENBERG SLC2W
  STRUCTURE.
• WE WERE AMAZED THAT WE DID NOT FIND EXTENSIVE AND
  SEVERE CORROSION IN THE SUBJECT 50 PLUS YEAR OLD
  STEEL STRUCTURE.

45
THIS PRESENTATION, FOR MOBILE SERVICE TOWER (MST)
STRUCTURE, WILL INCLUDE

• INTRODUCTION TO DELTA ROCKET LAUNCH COMPLEX AND
  PURPOSE OF THIS EVALUATION
• HISTORY SUMMARY FOR MST STRUCTURE
• PHOTOGRAPHS TO DEFINE STRUCTURAL SYSTEM AND
  STRUCTURAL COMPLEXITY OF MST
• GTSTRUDL STRUCTURAL ANALYSES METHODS, PROCEDURES,
  AND COMMANDS USED
• STRUCTURAL ANALYSES RESULTS
• SUMMARY, CONSLUSIONS, AND RECOMMENDATIONS
• REQUEST FOR SUGGESTIONS FROM OTHER ATTENDEES FOR
  IMPROVEMENTS IN ANALYSES METHODS WE USED

46
MST Analysis Tasks

• Perform field inspections to determine existing
  structural conditions
• Check structural design using 1997 Uniform
  Building Code loads with and without new clean
  room
• If any members fail code check, determine
  magnitude required to cause pushover for each
  load combination

47
MST Analysis Tasks continued

• Design for addition of new clean room structure
  support systems and prepare construction contract
  documents for this addition
• Design repairs for missing members, cut mems.
  corroded mems., corroded fasteners, deficient
  welds, etc. prepare construction contract
  documents for required repairs
• Original construction of New Mexico tower was not
  well documented
• During field inspections, original structure had
  to be field measured and documented
• Most of 1970s and 1990s structural
  modifications were well documented

48
GTSTRUDL Modeling
NORTH
49
GTSTRUDL Modeling

• 4104 Members
• 4 Cables
• 5 Counterweights
• Bridge Crane
• Earthquake
• Pacific Coast Winds
• Multiple structural modifications since original
  fabrication

50
GTSTRUDL ANALYSES METHODS, AND PROCEDURES USED
FOLLOW

• TO SAVE REPETITION, ONLY ONE MODEL WILL BE
  DISCUSSED IN THE FOLLOWING PRESENTATION OF
  GTSTRUDL METHODS AND PROCEDURES THAT WERE USED.
  ONE MODEL INCLUDED EXISTING STRUCTURE ONLY. A
  SECOND MODEL INCLUDED ADDITIONAL FRAMING AND
  LOADS FOR NEW CLEAN ROOM SYSTEM.
• RUNNING GTSTRDL NONLINEAR CABLE ELEMENTS AND
  NONLINEAR PUSH OVER ANALYSIS TOGETHER DID NOT
  WORK WELL AND WOULD NOT CONVERGE TO A SOLUTION
  WITH COMMANDS WE USED.

51

• CONSIDERING DEAD LOAD ONLY, 2 VERTICAL AND 2
  DIAGONAL CABLES WERE MODELED AS TRUE NONLINEAR
  CABLE ELEMENTS.
• NONLINEAR ANALYSIS WAS USED TO DETERMINE LENGTH
  FACTORS REQUIRED TO ACHIEVE KNOWN CABLE
  PRETENSION VALUES WITH CABLES ANCHORED BETWEEN
  FLEXIBLE STRUCTURAL ASSEMBLIES.

52

• CREATION OF WEST DIAGONAL CABLE AND PRETENSIONING
  (OTHER CABLES SIMILAR)
• TYPE SPACE TRUSS
• ELEMENT INCIDENCES
• 'IPC1' 2378 'IPC1'
• 'IPC2' 'IPC1' 'IPC2'
• 'IPC3' 'IPC2' 'IPC3'
• 'IPC4' 'IPC3' 289
• CONSTANTS
• E 2.20000e007 ELEMENTS 'IPC1' TO 'IPC4'
• ELEMENT PROPERTIES
• 'IPC1' TO 'IPC4' TYPE 'IPCABLE' AX 1.36000 SW
  0.392000 DIR -Y LF 0.900000
• DEFINE CABLE NETWORK 'WDIAG'
• INCLUDE ELEMENTS EXISTING 'IPC1' TO 'IPC4'
• ATTACH JOINTS 2378 289
• INITIAL TENSION T0 89500.0 TOLERANCE 200.000
  JOINT 289
• ADJUST LENGTH
• CONVERGENCE RATE 0.100000
• END

53

• ANALYSIS RESULTS OF WEST DIAGONAL CABLE AND
  PRETENSIONING (OTHER CABLES SIMILAR)
• CABLE GEOMETRY DATA
• ELEMENT UNSTRESSED
  STRESSED
• LENGTH
  LENGTH
• ------- ----------
  --------
• IPC1 307.812
  308.639
• IPC2 307.812
  308.650
• IPC3 307.812
  308.661
• IPC4 307.812
  308.672
• USING DISTANCE BETWEEN CABLE END POINTS (DISTANCE
  BETWEEN COORDINATES OF 2378 AND 289) AND
  COMPARING WITH THE STRESSED LENGTH, THE
  APPROXIMATE DEFORMATION OF A PRISMATIC MEMBER WAS
  DETERMINED.

54

• LOAD LIST ALL
• CABLE ANALYSIS DATA
• MAXIMUM NUMBER OF EQUILIBRIUM ITERATIONS 50
• CONVERGENCE TOLERANCE DISPLACEMENT 0.001000
• MAXIMUM NUMBER OF GEOMETRY ITERATIONS 25
• CONVERGENCE TOLERANCE GEOMETRY 0.001000
• LOADING 1200
• END
• LOAD LIST 1200
• PERFORM CABLE PRESTRESS ANALYSIS

55

• THEN CABLES WERE MODELED AS EQUIVALENT PRISMATIC
  MEMBERS. BY TRIAL AND ERROR, LENGTH FACTORS WERE
  DETERMINED THAT ACHIEVED CORRECT INITIAL TENSION
  IN EACH CABLE PRISMATIC MEMBER FOR DEAD LOAD ONLY
• USED FOLLOWING GTSTRUDL COMMANDS TO PRESTRESS
  PRISMATIC CABLE MEMBERS
• LOADING 4 'CABLES'
• PRE-TENSION IN CABLES ADDED IN AS SEPARATE
  LOAD
• MEMBER DISTORTIONS
• 6127 UNIFORM FR LA 0.1 LB 0.99 DISPL X -0.00726
• 6128 UNIFORM FR LA 0.1 LB 0.99 DISPL X -0.00752
• 5943 UNIFORM FR LA 0.1 LB 0.99 DISPL X -0.0031
• 5944 UNIFORM FR LA 0.1 LB 0.99 DISPL X -0.00337

56

• STATIC ANALYSIS WAS PERFORMED FOR ALL CODE
  REQUIRED COMBINATIONS OF DEAD, LIVE, WIND,
  EARTHQUAKE, AND BRIDGE CRANE LOADS.
• CODE CHECKS WERE PERFORMED FOR ALL MEMBERS AND
  FOR ALL LOADING COMBINATIONS. THESE RUNS
  REQUIRED APPROXIMATELY 2.5 HOURS EACH.

57
Deformed Structure (red)
Unloaded position (yellow)
58
Failed code check members (red)
59

• MEMBERS THAT FAILED CODE CHECKS WERE IDENTIFIED.
• HOW DO YOU EXPLAIN TO YOUR CLIENT THAT 262 /-
  STRUCTURAL MEMBERS FAILED CODE CHECK?

60

• Failed Members
• 4737 17 21 53 62
  66 93 94 95 96
• 116 117 118 119 120
  121 122 123 182 183
• 184 205 207 209 233
  240 260 261 263 265
• 267 287 288 361 362
  363 364 420 477 478
• 487 488 491 517 518
  519 520 521 528 529
• 530 531 539 664 666
  744 758 775 778 784
• 815 816 817 818 837
  838 839 840 841 842
• 843 844 845 874 895
  896 897 904 905 906
• 912 927 928 930 953
  954 961 971 981 982
• 983 984 986 987 988
  1018 1082 1083 1084 1085
• 1119 1134 1135 1141 1150
  1196 1197 1206 1207 1210
• 1213 1214 1236 1237 1238
  1239 1240 1246 1247 1248
• 1249 1250 1258 1379 1381
  1388 1390 1407 1409 1431
• 1452 1460 1463 1825 1826
  1839 1849 1850 1863 1983
• 1987 1988 1997 4105 4123
  4169 4295 4341 4363 4369
• 4408 4700 4733 4734 4901
  4903 4909 4920 4923 4924
• 4925 4935 4948 4957 4969
  4970 4974 5016 5103 5104
• 5105 5111 5113 5115 5148
  5163 5195 5206 5208 5209

61

• ONE LOAD CONBINATION AT A TIME WAS USED TO
  PERFORM A PUSH OVER ANALYSIS TO FAILURE.

62

• 50 LOAD LIST ALL
• 51 PUSHOVER ANALYSIS DATA
• 52 CONSTANT LOAD '1201'
• 53 INCREMENTAL LOAD '10030'
• 54 MAXIMUM NUMBER OF LOAD INCREMENTS 10
• 55 MAXIMUM NUMBER OF TRIALS 10
• 56 LOADING RATE 0.500000
• 57 CONVERGENCE RATE 0.800000
• 58 CONVERGENCE TOLERANCE COLLAPSE 0.010000
• 59 CONVERGENCE TOLERANCE DISPLACEMENT
  0.010000
• 60 MAXIMUM NUMBER OF CYCLES 10
• 61 DISPLACEMENT CONTROL OFF
• 62 END
• 63 PERFORM PUSHOVER ANALYSIS

63

• CABLE FORCE RESULTS WERE EVALUATED MANUALLY TO
  DETERMINE WHICH PUSH OVER ITERATION WOULD
• (1) CAUSE CABLE TO FAIL OR
• (2) CAUSE CABLE TO GO INTO COMPRESSION.
• (NOTE, GTSTRUDL KEEPS PUSH OVER RESULTS FOR LAST
  LOAD RUN ONLY.)

64

• New loading rate 0.400000
• Current load factor 2.40000
• Current load factor 2.46711
• INFO_STSLVP -- Pushover analysis structural
  instability detected.
• Time for 2 load adjustment trials, load increment
  7 126.87 seconds.
• New loading rate 0.429497E-01
• Current load factor 2.51006
• INFO_STSLVP -- Pushover analysis structural
  instability detected.
• WARNING_STPACP -- The sequence of 3 load
  adjustment trials in load increment 8
• failed to produce equilibrium convergence before
  collapse
• tolerance 0.100000E-01 was satisfied. Collapse
  condition may be indicated.
• Current loading rate 0.219902E-01
• INFO_STPACP -- The current collapse load
  factor 2.51006
• Load components and results are stored in the
  following intermediate loads
• PA100001 PA100002 PA100003 PA100004
• PA100005 PA100006 10030 PA100007
• INFO_STPACP -- The incremental loads above
  are stored in load group IncrLds .

65

• /----- Push-over Analysis Load Factor History
  -----/
• Load Increment Load Factor
• -------------- -----------
• PA100001 0.500000 DIAGONAL CABLES GO INTO
  COMPRESSION
• PA100002 1.00000
• PA100003 1.50000
• PA100004 2.00000
• PA100005 2.40000
• PA100006 2.46711
• PA100007 2.51006
• INFO_STPACP -- Time to complete pushover
  analysis 1366.34 seconds.
• 64 inactive members all
• 65 active members 6127 6128
• 66 LOAD LIST 'PA100001' 'PA100002'
  'PA100003' 'PA100004' 'PA100005' 'PA100006' -
• 67 _'PA100007'
• 68 LIST FORCES MEMBERS EXISTING
• RESULTS OF LATEST ANALYSES

66

• ANALYSIS NOTES IN COMPUTER RUN
• THE FOLLOWING PAGES DISPLAY THE FORCE IN THE
  DIAGONAL WIRE ROPES.
• IT SHOULD BE NOTED THAT WIRE ROPE CANNOT SUPPORT
  AXIAL COMPRESSION LOADS.
• THEREFORE, ALL INCREMENTAL LOADS THAT DEVELOP AN
  AXIAL COMPRESSION FORCE IN WIRE ROPE ARE INVALID
  AND WILL BE IGNORED.
• ADDITIONALLY, BECAUSE THE ANALYSIS RUN ASSUMED
  THAT WIRE ROPE COULD SUPPORT A COMPRESSION LOAD,
  WIRE ROPE MEMBERS WILL BE DELETED (OR TURNED
  INACTIVE) FOR THE PUSHOVER ANALYSIS FOR THIS
  PARTICULAR LOADING.
• IT SHOULD ALSO BE NOTED THAT THE FIRST
  INCREMENTAL LOAD CAUSES COMPRESSION IN THE WIRE
  ROPE, SO CONSEQUENTLY, THE PUSHOVER ANALYSIS
  RESULTS WITH THE DIAGONAL CABLES FOR THIS LOAD
  CASE WILL BE IGNORED.

67

• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• --- LOADING - PA100001 Incremental load 1 ---
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• MEMBER FORCES
• MEMBER JOINT /-------------------- FORCE
  --------------------//-------------------- MOMENT
  --------------------/
• AXIAL SHEAR Y SHEAR Z TORSIONAL BENDING Y BENDING
  Z
• 6127 30 -2113.0275879
• 6128 289 1293.8348389 COMPRESSION FORCE DEVELOPS
  IN WIRE ROPE.
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• --- LOADING - PA100002 Incremental load 2 ---
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• MEMBER FORCES
• MEMBER JOINT /-------------------- FORCE
  --------------------//-------------------- MOMENT
  --------------------/
• AXIAL SHEAR Y SHEAR Z TORSIONAL BENDING Y BENDING
  Z
• 6127 30 -25576.6406250
• 6128 289 -22146.2929688
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• --- LOADING - PA100003 Incremental load 3 ---
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------

68

• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• --- LOADING - PA100005 Incremental load 5 ---
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• MEMBER FORCES
• MEMBER JOINT /-------------------- FORCE
  --------------------//-------------------- MOMENT
  --------------------/
• AXIAL SHEAR Y SHEAR Z TORSIONAL BENDING Y BENDING
  Z
• 6127 30 -91155.2343750
• 6128 289 -87670.1328125
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• --- LOADING - PA100006 Incremental load 6 ---
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• MEMBER FORCES
• MEMBER JOINT /-------------------- FORCE
  --------------------//-------------------- MOMENT
  --------------------/
• AXIAL SHEAR Y SHEAR Z TORSIONAL BENDING Y BENDING
  Z
• 6127 30 -94293.8359375
• 6128 289 -90806.4062500
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------
• --- LOADING - PA100007 Incremental load 7 ---
• --------------------------------------------------
  --------------------------------------------------
  ------------------------------

69

• ITERATION STEP THAT CAUSED CABLE FAILURE OR CABLE
  COMPRESSION WAS IDENTIFIED.
• THIS DATA WAS USED TO DETERMINE MAGNITUDE
  MULTIPLIER REQUIRED TO CAUSE CABLE COMPRESSION OR
  TENSION FAILURE.
• THIS RESULT WAS CONSIDERED ONE POSSIBLE
  STRUCTURAL CAPACITY AT PUSHOVER FAILURE.

70

• THEN CABLES THAT COULD FAIL OR GO INTO
  COMPRESSION WERE MADE INACTIVE AND PUSHOVER
  ANALYSIS WAS REPEATED TO SEE IF ADDITIONAL
  STRUCTUAL CAPACITY EXISTED AFTER CABLES EITHER
  FAILED OR WENT INTO COMPRESSION.
• THIS RESULT WAS CONDIDERED A SECOND POSSIBLE
  STRUCTURAL CAPACITY FOR PUSHOVER FAILURE.

71

• 8 DEL MEMBERS EXISTING 6127 6128 ADD
• 9 load list all
• 10 form load 10030 from 30 0.43 31 -0.27
• 11 LOAD LIST ALL
• 12 NONLINEAR EFFECTS
• 13 GEOMETRY MEMBERS EXISTING
• 14 LOAD LIST ALL
• 15 PUSHOVER ANALYSIS DATA
• 16 CONSTANT LOAD '1201'
• 17 INCREMENTAL LOAD '10030'
• 18 MAXIMUM NUMBER OF LOAD INCREMENTS 10
• 19 MAXIMUM NUMBER OF TRIALS 10
• 20 LOADING RATE 0.500000
• 21 CONVERGENCE RATE 0.800000
• 22 CONVERGENCE TOLERANCE COLLAPSE 0.010000
• 23 CONVERGENCE TOLERANCE DISPLACEMENT
  0.010000
• 24 MAXIMUM NUMBER OF CYCLES 10
• 25 DISPLACEMENT CONTROL OFF
• 26 END

72

• THE SMALLER RESULT OF THESE STEPS ALLOWED
  DETERMINATION OF PUSHOVER CAPACITY FOR ENTIRE
  STRUCTURE FOR ONLY ONE LOAD COMBINATION.
• PROCESS WAS REPEATED FOR ALL LOAD COMBINATIONS.
• WITH WIND IN 4 DIRECTIONS,
• WITH EARTHQUAKE IN 4 DIRECTIONS,
• WITH BRIDGE CRANE LOADS AT VARIOUS
  POSITIONS.

73
THIS PRESENTATION, FOR MOBILE SERVICE TOWER (MST)
STRUCTURE, WILL INCLUDE

• INTRODUCTION TO DELTA ROCKET LAUNCH COMPLEX AND
  PURPOSE OF THIS EVALUATION
• HISTORY SUMMARY FOR MST STRUCTURE
• PHOTOGRAPHS TO DEFINE STRUCTURAL SYSTEM AND
  STRUCTURAL COMPLEXITY OF MST
• GTSTRUDL STRUCTURAL ANALYSES METHODS, PROCEDURES,
  AND COMMANDS USED
• STRUCTURAL ANALYSES RESULTS
• SUMMARY, CONSLUSIONS, AND RECOMMENDATIONS
• REQUEST FOR SUGGESTIONS FROM OTHER ATTENDEES FOR
  IMPROVEMENTS IN ANALYSES METHODS WE USED

74

• RESULTS FOLLOW THAT SHOW PUSHOVER FACTOR THAT
  MUST BE MULTIPLIED TIMES MINIMUM CODE SPECIFIED
  LOAD TO CAUSE STRUCTURAL FAILURE OF MST

75
(No Transcript)
76
THIS PRESENTATION, FOR MOBILE SERVICE TOWER (MST)
STRUCTURE, WILL INCLUDE

• INTRODUCTION TO DELTA ROCKET LAUNCH COMPLEX AND
  PURPOSE OF THIS EVALUATION
• HISTORY SUMMARY FOR MST STRUCTURE
• PHOTOGRAPHS TO DEFINE STRUCTURAL SYSTEM AND
  STRUCTURAL COMPLEXITY OF MST
• GTSTRUDL STRUCTURAL ANALYSES METHODS, PROCEDURES,
  AND COMMANDS USED
• STRUCTURAL ANALYSES RESULTS
• SUMMARY, CONSLUSIONS, AND RECOMMENDATIONS
• REQUEST FOR SUGGESTIONS FROM OTHER ATTENDEES FOR
  IMPROVEMENTS IN ANALYSES METHODS WE USED

77
SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

• 50 PLUS YEAR OLD MST STRUCTURE HAS BEEN RELOCATED
  AND EXTENSIVELY MODIFIED.
• STATIC STRUCTURAL ANALYSES INDICATE THAT 262 (6
  ) OF EXISTING STRUCTURAL MEMBERS DO NOT PASS
  STRENGTH REQUIREMENTS OF CURRENT CODES.

78

• ALTHOUGH SOME MEMBERS DO NOT PASS REQUIREMENTS OF
  CURRENT CODES, NONLINEAR PUSHOVER ANALYSES
  DEMONSTRATE THAT MULTIPLE AVAILABLE LOAD PATHS
  CAN PROVIDE SIGNIFICANT ADDITIONAL STRUCTURAL
  CAPACITY.
• ANALYSES USING GTSTRUDL INDICATE THAT
  EXISTING MST IS A VERY SAFE STRUCTURE WITH OR
  WITHOUT ADDITION OF PROPOSED NEW CLEAN ROOM
  STRUCTURAL MEMBERS.

79

• THE TWO GOVERNING LOAD COMBINATIONS WERE
• DEAD PARTIAL LIVE WIND FROM NORTH, AND
• DEAD PARTIAL LIVE EARTHQUAKE FROM NORTH.
• RESULTS DEMONSTRATE THAT MST CAN SURVIVE
  APPROXIMATELY 2.3 TIMES CODE SPECIFIED WIND OR
  EARTHQUAKE LOADS APPLIED TO STRUCTURE IN MOST
  CRITICAL DIRECTION.

80

• STRUCTURAL REPAIRS HAVE BEEN SPECIFIED
  IN CONSTRUCTION CONTRACT DOCUMENTS FOR REPAIR OF
  CORROSION DAMAGE, MISSING MEMBERS, CUT MEMBERS,
  DEFICIENT WELDS, AND CORRODED FASTENERS.
• ADDITION OF NEW CLEAN ROOM STRUCTURE HAS BEEN
  SPECIFIED IN CONSTRUCTION CONTRACT DOCUMENTS.

81

• STRUCTURAL MEMBERS THAT WERE ADDED TO SUPPORT NEW
  CLEAN ROOM WERE ARRANGED TO INCREASE STRUCTUAL
  CAPACITY OF MST.
• GOVERNING LOAD COMBINATION, WITH NEW CLEAN ROOM
  ADDITION, WAS DEAD PARTIAL LIVE EARTHQUAKE
  FROM NORTH.
• MINIMUM PUSHOVER FACTOR AFTER ADDITION OF NEW
  CLEAN ROOM FRAMING INCREASED FROM 2.32 TO 3.16
  (36).

82

• ADDITIONAL STRUCTURAL REPAIRS, STRENGTHENING,
  MODIFICATION, ETC. ARE NOT RECOMMENDED.
• IF IT HAD BEEN REQUIRED TO PROVIDE STRUCTURAL
  SAFETY, ALL MEMBERS THAT FAILED CODE CHECKS WOULD
  HAVE BEEN STRENGTHENED.

83

• STRENGTHENING OF 262 EXISTING MEMBERS WOULD BE
  VERY EXPENSIVE.
• THIS WORK WOULD ALSO BE EXTREMELY DIFFICULT TO
  SCHEDULE AROUND CHANGING LAUNCH SCHEDULES.

84

• STRUCTURAL STEEL MODIFICATIONS COULD NOT BE
  CONSTRUCTED WHILE A ROCKET IS ON THE PAD.
• ACCESS TO EXISTING MEMBERS TO PERFORM
  MODIFICATIONS AND COMPLETE INSPECTIONS OF
  COMPLETED WORK WOULD BE VERY DIFFICULT.
• MOST MEMBERS ARE IN CONGESTED AREAS THAT PREVENT
  USE OF CONVENTIAL MATERIAL HANDLING METHODS.
• MOST WORK AREAS WOULD REQUIRE USE OF POSITIVE
  FALL PROTECTION.

85

• RESULTS FROM NONLINEAR STRUCTURAL ANSLYSES, USING
  GTSTRUDL, HAVE ALLOWED US TO DEMONSTRATE TO OUR
  CLIENT THAT STRENGTHENING OF 262 MEMBERS IS NOT
  ABSOLUTELY REQUIRED.

86

• RESULTS FROM NONLINEAR STRUCTURAL ANSLYSES, USING
  GTSTRUDL, HAVE ALLOWED SAVINGS OF SEVERAL
  MILLION DOLLARS IN STRUCTURAL MODIFICATION COSTS
  THAT WERE BEING CONSIDERED.

87
THIS PRESENTATION, FOR MOBILE SERVICE TOWER (MST)
STRUCTURE, WILL INCLUDE

• INTRODUCTION TO DELTA ROCKET LAUNCH COMPLEX AND
  PURPOSE OF THIS EVALUATION
• HISTORY SUMMARY FOR MST STRUCTURE
• PHOTOGRAPHS TO DEFINE STRUCTURAL SYSTEM AND
  STRUCTURAL COMPLEXITY OF MST
• GTSTRUDL STRUCTURAL ANALYSES METHODS, PROCEDURES,
  AND COMMANDS USED
• STRUCTURAL ANALYSES RESULTS
• SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS
• REQUEST FOR SUGGESTIONS FROM OTHER ATTENDEES FOR
  IMPROVEMENTS IN ANALYSES METHODS WE USED

88
SUGGESTIONS FOR IMPROVEMENT OF ANALYSES METHODS

• JAMES, ANNE, AND I WOULD WELCOME SUGGESTIONS FROM
  OTHER ATTENDEES FOR WAYS TO IMPROVE THE ANALYSES
  METHODS WE HAVE USED TO BRUTE FORCE OUR SOLUTIONS
  FOR EACH LOAD COMBINATION.