Balcony Parapet Walls

Entering non-load-bearing walls into the StatiCAD-Yigma program may lead to incorrect analysis results.

According to the Earthquake Code, Article 5.8, walls with a gap of at least 10 mm between the top of the wall and the ceiling slab are considered non-load-bearing.

By default, the program treats all entered walls as load-bearing and calculates wall stiffnesses according to the earthquake code stiffness formula (k×A/h). Since no alternative formula is specified in the earthquake code, the same formula is applied regardless of whether the walls are connected to the slab (rigid diaphragm) or not.

In a building with a floor height of 3 m, parapet walls with a height of 1 m will be 3 times stiffer than a wall of the same area without adjacent doors or windows (since H is in the denominator of the stiffness formula). Since stiffness values are assigned to the walls, results may emerge as if the balcony walls are carrying a significant portion of the floor earthquake load. In this type of modeling, the results will deviate from the calculation principles required by the earthquake code, and risky buildings may appear non-risky, while non-risky buildings may appear risky.

Balcony walls can be entered into the system with the stiffness coefficient (k=0) by setting a custom value of zero in the wall property modification window. In this case, walls with a stiffness coefficient of zero will not be included in the shear force calculation. However, since vertical load transfers in the program are provided independently of wall top elevations, they may receive loads from the upper floor in vertical stress calculations.

For this reason, it is our opinion that balcony parapet walls (if not connected to the upper floor slab) should only be entered as loads in the structural model and should not be entered as wall elements.

We kindly request our users and authorities to show the necessary care regarding this matter to avoid calculation errors.

ÖZDEMİR YAZILIM