## 4 Comparison of Design Specification Provisions
### Comparison of the Equivalent Span of Continuous Composite Beams  
Generally, sagging moment regions and hogging moment regions are considered independently in design specifications. Therefore, the entire length of a composite beam divides into exterior spans, interior spans, and internal support spans. It assumes that an exterior span or an interior span can be treated as a separate simply-supported span. The equivalent span concept is applied, and the distance between moment inflection points is  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \(b_{\text{e}}\) Provisions & EN 1994-1-1 & AS/NZS 2327 & GB50017 & ANSI/AASC 360 \\ \hline Expressed as one-sided & Y & Y & N & Y \\ \hline Distinguishes exterior vs. & & N & Y & N \\ interior beam & N & N & Y & N \\ \hline Distinguishes M(+) region & & Y & Y & N \\ from M(\(-\)) region & & Y & N & N \\ \hline Distinguishes I girder from the & & Y & N & N \\ other beam & & Y & Y & N \\ \hline Distinguishes strength & & Y & Y & N \\ (ultimate) vs. service & & & & \\ \hline Considers the type of slab & N & Y & N & N \\ \hline Considers the opening or & & Y & N & N \\ cut-out of the slab & & & & \\ \hline Uses equivalent beam span & Y & Y & Y & N \\ \hline Value modified for concrete & & Y & N & N \\ cracking & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of provisions.  
used to determine each equivalent span. It can be seen that the most critical factor is the beam span or the equivalent beam span when using the design provisions to calculate the effective width of the slab in the four design specifications shown above. For this study, the research object was the rigid composite joint of steel moment-resisting frames (SMRFs). The mechanical properties of the fixed connection frame beam are similar to the continuous span composite beams described in the four design specifications mentioned above.  
Figure 6 shows definitions of the \"equivalent span\" in the EN 1994-1-1, AS/NZS 2327, GB50017, and ANSI/AASC 360 provisions. Because ANSI/AASC 360 does not use the \"equivalent span\" concept and only uses the beam span, all the equivalent span length ratios are equal to 1.0 in Figure 6. It can be seen from Figure 6 that for exterior spans, EN 1994-1-1 and AS/NZS 2327 using 85% of the beam span length as the effective span length, whereas GB50017 uses 80% of it. Like the exterior span, GB50017 uses 20% of the sum of the two adjacent beam span lengths for internal supports, whereas EN 1994-1-1 and AS/NZS 2327 using 25%. EN 1994-1-1 and AS/NZS 2327 using 70% of the beam span length for interior spans, and GB50017 uses 60% of the beam span length. We believe that the main reason for this difference is that the seismic design of the Chinese frame complies with strong joints and weak members. Therefore, reinforced joints are generally used for beam-column connections, and joint rotational stiffness tends to be substantial. However, European and Australian codes generally consider semi-rigid connections. Furthermore, effective span lengths equal the full continuous beam length (\(L1+L2+L3\)) for GB50017. For the other two provisions, EN 1994-1-1 and AS/NZS 2327, the sum of the effective beam span lengths is longer than the total continuous beam length (\(L1+L2+L3\)) because of using the distance between inflection points under uniformly distributed loads [18]. For example, the column distances of a steel moment resistance frame in the same direction are generally equal, and the spans of the beams are also the same. This means that beam span \(L1\) equals \(L2\) as well as \(L3\), so that the sum of the effective beam span lengths is 10% more than the total continuous beam length.