Previously, Structural engineers in Saudi Arabia use British or American codes based on their knowledge background because there was no clear guideline or code for them to use in designing . Moreover, Uniform building code provided limited information about seismic zone for few cities in Saudi Arabia .

In 2007 Saudi Building code (SBC) was published and since then we have clear code that satisfy our requirements.Unfortunately, we found out there are three common mistakes, the structural engineers always do when using the Saudi building code.

1-    Mix of codes requirements :

Recently, structural engineers in KSA are using IBC 2012 code /ASCE 7-10 standards along with wind and seismic map provided in SBC code; ignoring the fact of SBC is based on (IBC 2003) code/ ASCE7-02. Which lead to underestimate wind design load, and in some cases it may cause a building failure.

ASCE 7-10 contains significant changes from ASCE 7-02 in the areas of seismic design, wind design, and more.

In ASCE7-10 the wind speed values represent “Ultimate” wind speeds , therefore, Strength design level wind speeds replaces the ASD level wind speeds. But in SBC the wind speed value represent “service “wind speed.

This is the reason the load factor is 1.0 for wind instead in ASCE7-10 While the load factor is 1.6 in SBC code .

Load combinations as per (ASCE 7-10) as follows :

Load combinations as per Saudi building code (SBC) as follows

Therefore, in order to use ASCE7-10 you , the wind speed should be modified .

Fortunately, ASCE7-10 provide a table in the commentary to ease the transition, that provide conversation from the strength wind speed and wind service speed of ASCE7-05 as shown below :

2-    Missing load combination :

The SBC mentioned the load combination in section 2.3.2. However, there is additional load for designing concrete and masonry mentioned in the exception clause No.2 which usually unobserved .

3-    Design coefficients and factors for basic seismic force-resisting system 

SBC code is using lower value of the response modification coefficient(R), seismic over-strength factor and defection amplification factor Cd than IBC code .

New version of SBC is under reviewing and expected to be released by end of this year .