Presence of a bond beam in the middle and at the top of a wall (Intermediate bond beam)

Since this situation has no counterpart in the earthquake code, no special definition has been made in the program.

Drawing beam bond beams on top of walls causes the load transfer to be performed twice. It produces no change in the static analysis other than an increase in weight.

Drawing two superimposed walls on the same storey with different lower and upper elevation values means that the seismic forces are distributed between the two overlapping walls. This yields an erroneous analysis result.

Two types of definition can be applied for this situation:

1. The intermediate bond beam can be treated as a rigid diaphragm, and the storey definition approach can be adopted.

That is:

Storey name: ground floor lower part, height: 2 m

Storey name: Ground floor upper part, storey height: 90 cm, for example.

This approach may result in the building being analysed as less risky than it actually is.

2. The intermediate beam bond beam can be ignored (if desired) and the extra weight of the intermediate bond beam can be entered as an extra load on the walls and the lintels above windows.

In this case, the storey height minus the bond beam height at the top of the wall is taken as the effective wall height in the wall slenderness check.

Method 1 may be considered to give a more accurate calculation of the wall compressive stress due to the slenderness ratio calculation. (This is an engineering judgement, not a definitive conclusion.) However, it may be considered that the shear stress calculation could deviate from the approach given in the code calculation. As is known, wall compressive strength checks are not used in risk assessment.

Method 2 may be considered to give a more code-compliant result in terms of shear stresses.

OUR RECOMMENDATION AND OPINION

As a solution recommendation for the situation in question, it is advised that two models be created and saved according to the definitions of Method 1 and Method 2;

That the wall compressive strength checks be taken from the data file saved according to Method 1 in the calculation report;

That the wall shear stress, risky building performance analysis, and other earthquake-related reports be taken from the report saved according to Method 2.

It is recommended that the procedure be explained with justification in the technical report.