내진강구조물의 용접재료 시험 규정의 변화
2019. 08. 28.
발표자 : 서 승 은
1994년 LA Northridge 지진 피해 내역
* 리히터 스케일 7 의 강진.
* LA 지역 강구조물 빌딩의 조사된 부재 중 32 % 에서 균열발생.
* 조사된 부재의 15.7 % 는 기둥-보 접합용접에서 균열 발생.
* Flange 이음 용접균열 중,
70 % - beam bottom flange 이음 용접부.
30 % - beam top flange 이음 용접부.
1994년 미국 Northridge 대지진 이후, 미국 Codes & Standards의 변화
ASTM A992 - 2002, 화학성분 검사에 V, Cb, Cu, Ni, Cr, Mo, N 성분의 상한 값 추가.
Ys/Tu 의 상한 값, 0.85 를 신설 함.
AISC 360-2005, 2016, Specification for Structural Steel Buildings,
AISC N690-2006, 2016, Specification for Safety-Related Steel Structures for Nuclear Facilities.
AISC 341-2005, 2016, Seismic Provisions for Structural Steel Buildings,
AISC 358-2005, 2016, Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications,AISC 327-2005, 2018, Seismic Design Manual, 3rd edition.
ASCE-7-2005, 2010, Minimum Design Loads for Buildings and Other Structures.
AWS D1.1-2002, 2015, Structural Welding Code - Steel,
AWS D1.8-2005, 2016, Structural Welding Code - Seismic Supplement,
AISC 341-16, Seismic Provisions for Structural Steel Buildings
A3.1 Material Specifications : The structural steel used in the SFRS described in Chapters E, F, G
and H shall meet one of the following ASTM Specifications :
- 강재 사양 : A36, A53, A500 Gr. B, C, A501, A529, A572 Gr. 42, 50, 55, A588,
A913 Gr.50, 60, 65, A992, A1011 HSLA Gr.55, A1043,
A3.3 Heavy Sections :
- For structural steel in SFRS, hot rolled shapes with flange thickness equal to or greater than
1-1/2 in. shall have a minimum Charpy V-Notch (CVN) toughness of 20 ft-lb @ 21℃.
- Plates with thickness equal to or greater than 2 in. shall have a minimum Charpy V-Notch (CVN)
toughness of 20 ft-lb @ 21℃.
A3.4 Consumables for Welding :
4a. Seismic Force-Resisting System Welds : All welds in members and connections in the SFRS
shall be made with filler metals meeting the requirements specified in clauses 6.1, 6.2 and 6.3 of
Structural Welding Code - Seismic Supplement (AWS D1.8)
4b. Demand Critical Welds : Welds designated as demand critical shall be made with filler metals
meeting the requirements specified in AWS D1.8 clauses 6.1, 6.2 and 6.3.
User Note : AWS D1.8 requires that all seismic force-resisting system welds are to be made with
filler metals classified using AWS A5 standards that achieve the following mechanical properties :
Filler Metal Classification Properties for Seismic Force-Resisting System Welds
PropertyClassification
70 ksi 80 ksi 90 ksi min.
Yield Strength, ksi 58 min. 68 min. 78 min.
Tensile Strength, ksi 70 min. 80 min. 90 min.
Elongation, % 22 min. 19 min. 17 min.
CVN Toughness, ft-lb *a 20 min. @ -18℃ *a 25 min. @ -30℃
*a. Filler metals classified as meeting 20 ft-lbf min. at a temperature lower than -18℃ also meet this requirement.
Mechanical Properties for Demand Critical Welds
PropertyClassification
70 ksi 80 ksi 90 ksi min.
Yield Strength, ksi 58 min. 68 min. 78 min.
Tensile Strength, ksi 70 min. 80 min. 90 min.
Elongation, % 22 min. 19 min. 17 min.
CVN Toughness, ft-lb *b, c 40 min. @ 20℃ 40 min. @ 10℃
*b. For LAST of +10℃. For LAST less than +10℃, see AWS D1.8 clause 6.2.2.*c. Tests conducted in accordance with AWS D1.8 Annex A meeting 40 ft-lb min. at a temperature lower than +20℃ also meet this requirement.
주 : a. 표시된 용접이음. 기둥 약한 축 방향으로 용접 이음되는 부재는 SFRS 부재가 아니다.
1. D1.8-DC 표시는 내진용접으로 설계된 용접을 의미한다.
2. D1.8 표시는 D1.8 규정에 의해 규제되는 용접을 의미하나, 내진용접으로 분류되지 않는다.
3. D1.1 표시는 D1.1 규정만 적용되는 용접을 의미한다.
그림 C-1.1 – RBS/기둥의 강한 축 방향과 빔 용접이음의 예
(C-1.2.1의 2, 3, 4 항 참조)
주 : a. 표시된 용접이음. 기둥 약한 축 방향으로 용접 이음되는 부재는 SFRS 부재가 아니다.
1. D1.8-DC 표시는 내진용접으로 설계된 용접을 의미한다.
2. D1.8 표시는 D1.8 규정에 의해 규제되는 용접을 의미하나, 내진용접으로 분류되지 않는다.
3. D1.1 표시는 D1.1 규정만 적용되는 용접을 의미한다.
그림 C-1.2 – Eccentric Brace/Link/Column 용접이음의 예
(C-1.4.1의 2, 3, 4 항 참조)
주 : a. 표시된 용접이음. 기둥 약한 축 방향으로 용접 이음되는 부재는 SFRS 부재가 아니다.
1. D1.8-DC 표시는 내진용접으로 설계된 용접을 의미한다.
2. D1.8 표시는 D1.8 규정에 의해 규제되는 용접을 의미하나, 내진용접으로 분류되지 않는다.
3. D1.1 표시는 D1.1 규정만 적용되는 용접을 의미한다.
그림 C-1.3 – WUF-W/기둥 강한 축 방향 용접이음의 예
AWS D1.8, clause 6.2.2 Lowest Anticipated Service Temperature Applications.
For Demand Critical welds in applications where the Seismic Force Resisting System is subject to
service temperatures below +10℃ following completion of the structure, the minimum CVN of
40 ft-lbf as prescribed by 6.2.1 shall be provided at a test temperature not more than 10℃ above
the LAST for 70 ksi and 80 ksi filler metals and at LAST for 90 ksi filler metals.
AWS D1.8, clause 6.7 Maximum Interpass Temperature
6.7.1 Standard Maximum Interpass Temperature :
- The max. interpass temperature shall not exceed 300℃, unless an alternate value is qualified
in accordance with 6.7.2.
- The max. interpass temperature shall be measured at a distance of 1 in. to 3 in. from the joint.
a. 최소 예열온도와 최소 층간온도는 A 위치에서 측정. 용접 경계선에서 최소 3 in. [75 mm] 또는 강재 두께 t 중
큰 거리에서 측정.
주 : 최대 층간온도는 B 위치에서 측정. 용접 경계선에서 1 in. - 3 in. [25 mm - 75 mm] 범위에서 측정.
그림 C-6.1 - 예열온도와 층간 온도의 측정 위치 (C-6.7.1 참조)
AWS D1.8, clause 6.8 Heat Input
6.8.1 Heat Input Limits : Acceptable heat input limits on WPSs for Demand Critical welds shall
include the following, at the Contractor's option :
(1) The heat input range qualified by testing in accordance with Annex A.
(2) For carbon steel FCAW electrodes classified with the supplemental designator "-D," the heat
input range prescribed in clause 17 of AWS A5.20-2005.
(3) The heat input range prescribed in AWS A5.20-2005 Clause 17 for the following 70 ksi or 80
ksi tensile strength filler metals when optionally tested to the requirements of the AWS A5.20
"-D" supplemental designator :
(a) Low alloy FCAW electrodes, classified to AWS A5.29 ;
(b) Carbon steel GMAW composite (metal cored) electrodes, classified to AWS A5.18, and
low alloy GMAW composite (metal cored) electrodes, classified to AWS A5.28 ;
(c ) Carbon steel SAW electrode/flux combinations, classified to AWS A5.17, and low alloy
SAW electrode/flux combinations, classified to AWS A5.23 ;
(5) The heat input range prescribed in AWS A5.36-2012 Clause 16 for carbon and low alloy steel
FCAW and GMAW-metal core electrodes classified with the supplemental designator "-D" :
Annex A - WPS Heat Input Envelope Testing of Filler Metals for Demand Critical Welds.
Table A.1 Heat Input Envelope Testing - Heat Input, Preheat, and Interpass Temperatures.
Suggested Heat InputMax. Preheat Temperature
Max. Interpass Temperature
Low Heat Input Test 30 kJ/in. ± 20% 40 ℃ 120 ℃
Suggested Heat InputMin. Preheat
Temperature *aMin. Interpass Temperature *a
High Heat Input Test 80 kJ/in. ± 20% 120 ℃ 240 ℃
*a. For the high heat input test, the test plate shall be heated to the minimum preheat, and then welding shall
begin. Welding shall continue without substantial, deliberate interruption until the minimum interpass temperature
is obtained. After the test plate has been heated to the min. interpass temperature, all subsequent weld pass
shall be made at a temperature not less than the min. interpass temperature.
Should the test plate temperature fall below the min. interpass temperature for any reason, the test plate shall
be heated to a temperature not less than the min. interpass temperature before welding resumes. If the required
interpass temperature is not achieved prior to interruption of the welding operations, welding shall not resume
untill the test assembly has been heated to the prescribed min. interpass temperature.
Table A.2 All Weld Metal Mechanical Properties
Nominal Electrode Classification Strength 70 ksi 80 ksi 90 ksi min.
Yield Strength, ksi, 0.2% offset method 58 min. 68 min. 78 min.
Tensile Strength, ksi 70 min. 80 min. 90 min.
Elongation, %, measured in a 2 in. gage length
22 min. 19 min. 17 min.
CVN Toughness when LAST is greater than or equal to +10℃, ft-lbf
40 min. @ +21℃ 40 min. @ +10℃
CVN Toughness when LAST is less than +10℃, ft-lbf
40 min. @ LAST + 10℃ 40 min. @ LAST
A5. Welding of Test Plate :
A5.1 Preheat and Interpass temperature ; The test assembly shall be heated to the specified
preheat temperature, measured at a location 1 in. from the center of the groove at the location
shown in Fig. A.1. When max. interpass temperature prescribed in Table A.1 is exceeded, the test
plate shall be allowed to cool until the prescribed temperature is achieved.
A5.2 Heat Input ; The test plate shall be welded with a combination of variables that will
generate the desired high or low level of heat input. The test plate shall be completed such that
the computed heat input value for each weld pass does not vary from desired heat input level by
more than ±20%.
A5.3 Warpage ; A completed test plate that is warped more than 5° from flat shall be discarded.
Welded test assemblies shall not be straightened.
A5.4 Thermal Treatment ; No thermal treatment of weldment or test specimens is permitted,
except that machined tensile test specimens may be aged at 95℃ to 105℃ for up to 48 hours,
then cooled to room temperature, before testing.
A7. Acceptance Criteria :
A7.1 The all-weld-metal tensile test specimens shall meet strength and ductility requirements as
prescribed in Table A.2, as applicable.
A7.2 CVN Toughness Requirements. The lowest and highest values obtained from five test
specimens from each test plate shall be disregarded. Two of the remaining three values shall
equal or exceed the specified CVN toughness of 40 ft-lbf energy level at the testing temperature.
One of the three may be lower, but not lower than 30 ft-lbf.
The average of the three shall not be less than the requirements of Table A.2. (40 ft-lbf).
Root Opening (R) Groove Angle (α)
Option 1 1/2 in. [12 mm] 45°
Option 2 5/8 in. [16 mm] 20°
*a ; For SAW, test plate thickness may be 1 in. [25 mm].
Figure A.1 – Heat Input Envelope Test Plate (see A4, A5.1, A6)
AWS A5.20 Procedure Requirements for "-D" Optional Supplemental Designator
OptionalSupplementalDesignator
Procedure Heat Input(Fast or SlowCooling Rate)
PreheatTemperature
℃
InterpassTemperature
℃
Heat InputRequirement for
Any Single Pass *a
Required AverageHeat Input forAll Passes *a
D
low(fast cooling rate)
20℃ ± 15℃ 90℃ ± 15℃
For electrode diameters 〈 2.4 mm
33 kJ/in. 30 +2, -5 kJ/in.
For electrode diameters ≥ 2.4 mm
44 kJ/in. 40 +2, -5 kJ/in.
high(slow cooling rate)
150℃ ± 15℃ 260℃ ± 25℃ 75 kJ/in. 80 +5, -2 kJ/in.
*a. Does not apply to first layer. The first layer may have one or two passes.
AWS A5.36 Procedure Requirements for "-D" Optional Supplemental Designator
OptionalSupplementalDesignator
Procedure Heat Input(Fast or SlowCooling Rate)
PreheatTemperature
℃
InterpassTemperature
℃
Heat InputRequirement for
Any Single Pass *a
Required AverageHeat Input forAll Passes *a
D
low(fast cooling rate)
50℃ max. 120℃ max
For electrode diameters 〈 2.4 mm
38 kJ/in. max. 24 kJ/in. - 36 kJ/in.
For electrode diameters ≥ 2.4 mm
44 kJ/in. max. 35 kJ/in. - 42 kJ/in.
high(slow cooling rate)
120℃ min. 240℃ min. 65 kJ/in. min. 65 kJ/in. - 85 kJ/in.
*a. Does not apply to first layer. The first layer may have one or two passes.
* Heat Input Envelope Testing - Heat Input, Preheat, and Interpass Temperatures 비교표
Suggested Heat InputMax. Preheat Temperature
Max. Interpass Temperature
Low Heat
Input Test
D1.8, Annex A 30 kJ/in. ± 20% 40 ℃ 120 ℃
A5.20, "-D" 30 +2, -5 kJ/in. 20℃ ± 15℃ 90℃ ± 15℃
A5.36, "-D" 24 kJ/in. - 36 kJ/in. 50℃ max. 120℃ max
Suggested Heat InputMin. Preheat Temperature
Min. Interpass Temperature
High Heat
Input Test
D1.8, Annex A 80 kJ/in. ± 20% 120 ℃ 240 ℃
A5.20, "-D" 80 +5, -2 kJ/in. 150℃ ± 15℃ 260℃ ± 25℃
A5.36, "-D" 65 kJ/in. - 85 kJ/in. 120℃ min. 240℃ min.