dbdsoft_supplementpplement

DBDsoft v.0.9.0.3 Supplement of 3

DBDsoft v.0.9.0.3

HELP SYSTEM SUPPLEMENT

1. Processor: Selection of Performance Criteria Combinations

Given that the amplification of forces due to higher mode effects depends on the ductility demand to

which the structure is subject, DBDsoft v.0.9.0.3 gives the user the possibility of specifying a Performance

Criteria Combination to be used for capacity design different from the one used for the general design

process (i.e. the design of plastic hinges). When different performance criteria combinations are specified

for general design and capacity design, the reported required flexural strengths of plastic hinges

correspond to the forces related to the design performance criteria, while the reported capacity protected

strengths of elements required to remain elastic are those obtained by using the capacity design criteria

instead. Given that DBDsoft does not compare one and the other, it is up to the user to decide if the

required capacity protected strengths obtained are satisfactory for the structure to remain elastic under

the design forces.

The selection of which performance criteria combinations to use for each purpose must be carried out

within the Design Case module of the Processor Phase. This module presents the following appearance:

For more information regarding Capacity Design, please refer to the corresponding section of the Help

System.

2. Post-Processor: "Results" tab

DBDsoft v.0.9.0.3 provides the user more information regarding the displacement ductility demands of

both the overall structural system and its components.

The user can find that the displacement ductility demand of the system is now reported in the "Results" tab

of the Post-Processor, just above the system's equivalent viscous damping. For the case of pure frame

structures, storey ductility demands are also reported on the last column of the table. When the structure

consists only of cantilever RC walls, the displacement ductility demand is reported both in the "Results" tab

and the "Walls Base Details" tab. Finally, in the case of frame-wall structures, the displacement ductility

Select load combination.

Select performance criteria combination

to be used for general design.

Select performance criteria combination

to be used for capacity design.

Specify the overstrength factor to be

used for capacity design.


demand of the frames is reported to the right of the system's displacement ductility demand, while that of

the walls can be found in the "Walls Base Details" tab. The following images illustrate this.

Example of Output for a Pure Frame System

Example of Output for a Pure Wall System

Storey-by-storey displacement

ductility demands

System's displacement

ductility demand

Each wall's displacement

ductility demand


ductility demand


Example of Output for a Frame-Wall System

3. Processor: Calculation of Maximum Design Base Shear

Previous versions of DBDsoft already had this feature, but the way it is obtained was missing from the Help

System.

The upper limit imposed to the design base shear ("Vb max", as reported in the "Results" tab of the Post-

Processor) is calculated as suggested in Art. 5.1 of the DBD12 Model Code (Sullivan et al. 2012):

�� = 2.5 · � · �� · �� · 9.81�� · ��

Rξ is the design spectrum reduction factor, S is the soil factor, PGA is the design peak ground acceleration in

rock, and me is the effective mass of the equivalent single-degree-of-freedom system. Note that the current

version of DBDsoft considers S = 1.00. This means that, when introducing the parameters for the definition

of the design displacement spectrum, the PGA value should already include the effect of the soil type.

References

Sullivan, T.J., Priestley, M.J.N., Calvi, G.M., Editors (2012) “A model code for the Displacement-Based Seismic Design of Structures,

DBD12”, IUSS Press, Pavia, Italy, 105 pages.

Frames' displacement

ductility demand


ductility demand

dbdsoft_supplementpplement

Documents