9.7. CENTRAL CROSSED STEEL FRAMES WITH LIMITED DUCTILITY LEVEL
Rules to be applied in the dimensioning of central braced steel frames with limited ductility level are given below.
9.7.1. General Conditions
9.7.1.1 - In beams, columns and crosses of steel frames with limited ductility level, head width / thickness , body height / thickness and diameter / thickness ratio shall not exceed λ md limit values given in Table 9.3 .
9.7.2. System Analysis
The strengths required in dimensioning the columns, beams and joints of the central braced steel frame systems with limited ductility level shall be determined by taking into account the load combinations including the strength excess coefficient defined in 9.2.6 and the earthquake effect amplified by D.
9.7.3. Crosses
Cross members of central braced steel frames with limited ductility level shall be dimensioned to meet the following conditions.
9.7.3.1 - The slenderness ratio of the cross members (rod buckling length / radius of inertia) shall not exceed the limit value KL i / ≤ 200. However, if V or inverted V shaped cross patterns are used, the requirement for slenderness ratio will be met.
9.7.3.2 - In steel frames with central braces of limited ductility level, it may be permitted to use multi-piece elements, provided that the parts forming the cross-section of the cross members behave as one piece. This requirement should be met by tie plates placed equally spaced in multi-piece bars with a distance between the elements equal to the thickness of a bond plate, and in other cases by mesh connections (mesh elements). Section 8.4 of the "Regulation on Design, Calculation and Construction Principles of Steel Structures" shall be based on the design of the interconnecting elements of multi-piece crosses.
9.7.3.3 - Braces shall be dimensioned considering the load combinations including the earthquake effect given in 9.2.5 .