SISTEMA DE CONECTIVIDAD

Design Forces P (kips) Vframe (kips) Vlong (kips) Dead (D) −6.20 0.00 0.00 Collateral (C) −2.57 0.00 0.00 Earthquake Eh, Frame ±0.72 0.00 0.00 Earthquake Eh, Long. 0.00 0.00 0.00 Earthquake Ev = 0.048(D + C) ±0.42 0.00 0.00 Design Building A (R = 3) Design Forces P (kips) Vframe (kips) Vlong (kips) Dead (D) −6.20 0.00 0.00 Collateral (C) −2.57 0.00 0.00 Earthquake Eh, Frame ±0.84 0.00 0.00 Earthquake Eh, Long. 0.00 0.00 0.00 Earthquake Ev = 0.048(D + C) ±0.42 0.00 0.00 Design Building B Design Forces P (kips) Vframe (kips) Vlong (kips) Mframe (ft-kips) Dead (D) −6.92 −0.13 0.00 1.90 Collateral (C) −2.56 −0.05 0.00 −0.76 Earthquake Eh, Frame ±0.09 ±3.60 0.00 ±45.78 Earthquake Eh, Long. 0.00 0.00 0.00 0.0 Earthquake Ev = 0.2(D + C) ±1.90 0.00 0.00 ±0.23

Note that the columns are pinned at the base and transmit no moment to the foundations for Design Building A. Also, for Design Building B, the columns are pinned at the base in the longitudinal direction but are fixed at the base in the transverse direction.

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2.8 WELDING ISSUES AND QUALITY ASSURANCE REQUIREMENTS

2.8.1 Welding Issues

For seismic applications, AISC 341-05 references the 2004 version of AWS D1.1. Section 7.3 and Appendix W of the Seismic Provisions give an expanded list of welding requirements over those in previous editions.

First, all member and connection welds within the Seismic Load Resisting System (SLRS) are required to be made with filler metals with a Charpy V- Notch (CVN) toughness of 20 ft-lb at a temperature of 0° F (- 18° C).

Welds designated as demand critical have additional requirements, including: 1. Charpy V-Notch toughness of 20 ft-lb at a temperature of -20° F, as

well as 40 ft-lb at a temperature of 70° F as determined by an appropriate AWS classification test methods.

2. Charpy V-Notch toughness of 40 ft-lb at a temperature of 70° F as determined by Appendix X, or other approved method when the steel frame is normally enclosed and maintained at a temperature of 50° F or higher. If the structure is maintained at a temperature lower than 50° F, the qualification temperature for Appendix X is to be a maximum temperature of 20° F higher than the anticipated service temperature.

3. The following electrodes are exempt from the production lot testing requirement when the CVN toughness of the electrode is  20 ft-lb at a temperature not exceeding -20° F as determined by AWS

classification test methods.

a. SMAW electrodes classified in AWS 5.1 as E7018 or E7018-X b. SMAW electrodes classified in AWS 5.5 as E7018-C3L or

E8018-C3

c. GMAW solid electrodes

It should be noted that the manufacturer’s certificate of compliance shall be considered sufficient evidence of meeting this requirement. Specific examples given for demand critical welds include:

1. Complete-joint-penetration (CJP) welds between the column and base plate when CJP groove welds used for column splices in the

designated SLRS have been designated as demand critical.

2. Typical examples of demand critical welds in special moment frames (SMF) and intermediate moment frames (IMF) include beam flange to column welds, welds of single plate shear connections to columns, beam web to column welds, column splice welds, and base plate to

column base welds. These requirements would also apply for beam to end-plate moment connection welds.

3. Typical examples of demand critical welds in ordinary moment frames (OMF) include beam flange to column welds (also beam to endplate welds), welds of single plate shear connections to columns, and beam web to column welds. These requirements would also apply for beam to end-plate moment connection welds.

4. Typical examples of demand critical welds in eccentrically braced frames (EBF) include CJP groove welds between link beams and columns. Other welds such as those joining the web plate to flange plates in built-up EBF link beams, as well as column splice welds made with CJP groove welds, should also be considered as demand

critical welds.

All welding is to be performed in accordance with a welding procedure

specification (WPS) as required in AWS D1.1 and approved by the engineer of record. All WPS should be verified to ensure that the essential variables of the WPS are within the operating parameters provided by the filler metal

manufacturer. Secondly, it should be verified that the selected filler metal is classified by the filler metal manufacturer with the appropriate level of CVN toughness. The 2006 IBC requires the submittal of filler metal manufacturer’s certifications of compliance for their filler metals in IBC Table 1704.3.

2.8.2 Quality Assurance

Quality assurance inspection performed by an independent inspection agency, is not a requirement of AWS D1.1. Inspection is required by AWS D1.1, but is addressed generically in a form that includes both the fabricator’s or erector’s inspection and the outside inspection that is provided by, but at the prerogative of, the owner. AWS D1.1 does include visual quality criteria, nondestructive testing (NDT) methodology and NDT quality criteria, but does not specify the location or types of welds that require NDT. This task is left to the engineer. AWS D1.1 does not contain specific quality criteria applicable for seismic loading, low cycle fatigue or plastic hinging regions, addressing only static (elastic) and high-cycle fatigue applications. Any special quality requirements for seismic applications are left to the engineer.

AISC 341-05 contains the provision for and requirements of a quality assurance plan in Section 18 and Appendix Q. The plan must meet any building code requirement such as those in the 2006 IBC, in addition to any requirements of the engineer. The emphasis is placed upon visual inspection. Nondestructive Testing (NDT), however, is required for CJP and PJP groove welds along with other items as detailed in Appendix Q. The form of NDT is specified within Appendix Q, based on the tested item.

The 2006 IBC requires special inspection for steel construction, with a few exceptions as noted in Section 1705.3. Special inspection is performed by

2-117 inspections by the building official. Special inspection includes an inspection of

the fabricator’s operations and quality control procedures, unless the fabricator is otherwise approved by the building official. Structural steel welding

operations must receive continuous special inspection, except for single-pass fillet welds 5/16" or less, for which periodic special inspection is permitted. Section 1705 of IBC 2006 requires a quality assurance plan for seismic-force- resisting systems in Seismic Design Categories C, D, E or F. The quality assurance plan must be prepared by a registered design professional and specify the special inspection requirements and testing requirements, including the type of testing and frequency of testing. Structural observation by the engineer or his or her designated representative is also a requirement. The exact extent of additional special inspection, testing and structural observation for seismic applications is not defined within the IBC, but is rather left to the determination of the registered design professional. AISC 341-05 gives appropriate guidance in this area.

The fabricator and erector must complete a statement of responsibility acknowledging their awareness of the quality assurance plan, their plans and procedures for providing quality control to achieve the contract requirements, and identification of those individuals responsible for performing such

functions.

The 2006 IBC Section 1704.2.2 allows in-shop quality assurance activities to be waived if welding is performed on the premises of an approved fabricator.