Brazilian load combinations

 

2012.0

Brief introduction

The ultimate and serviceability limit state combinations are implemented according to Brazilian Code ABNT NBR 6118:2003.

Detailed Technical information

ULS

It is possible to define five ultimate concrete combinations.

Concrete - ULS - Regular

Each combination should include the permanent actions and the principal variable action with their characteristic values as well as the other variable actions considered secondary with their reduced combination values

The following combinations are generated :

Concrete - ULS - Special 0

Each combination has to include the permanent actions and the special variable action when it exists, with their characteristic values and the other variable actions having not to be disregarded probability of occurring simultaneously, with their reduced combination values.

The following combinations are generated :

Concrete - ULS - Special 2

Each combination has to include the permanent actions and the special variable action when it exists, with their characteristic values and the other variable actions having not to be disregarded probability of occurring simultaneously, with their reduced combination values.

When Fg1k or Fg1exc act during a very short period of time or have a very low probability of occurring, ѱ0j, may be replaced by ѱ2j. That might be the case for fire and seismic actions.

The following combinations are generated :

Concrete - ULS - Exceptional 0

Each combination has to include the permanent action and the special variable action, when it exists, with their representative values and other variable actions with not to be disregarded probability of occurring simultaneously, with their reduced combination values. In these cases are included, among others, seism, fire and progressive collapse.

The following combinations are generated :

Concrete - ULS - Exceptional 2

Each combination has to include the permanent action and the special variable action, when it exists, with their representative values and other variable actions with not to be disregarded probability of occurring simultaneously, with their reduced combination values. In these cases are included, among others, seism, fire and progressive collapse.

When Fg1k or Fg1exc act during a very short period of time or have a very low probability of occurring, ѱ0j, may be replaced by ѱ2j. That might be the case for fire and seismic actions.

The following combinations are generated :

For more info on the ULS combination formulas above, please check the ABNT NBR 6118:2003 - 11.8.2 - Ultimate combinations (Table 11.3). Additional info on partial safety factors may be found in 11.7.1 - Partial safety factors of actions at ultimate limit states (ULS) .

SLS

It is possible to define three serviceability concrete combinations.

Concrete - SLS - Unfreq.

In the unfrequent service combinations the principal variable action Fq1 is used with its characteristic value of Fq1k and all other actions are used with the frequent values ѱ1 Fqk.

The following combinations are generated :

Concrete - SLS - Freq.

In frequent service combinations the action of the principal variable Fq1 is used with its frequent value ѱ1 Fq1k and all other variable actions are used with its quasi-permanent values ѱ2 Fqk.

The following combinations are generated :

Concrete - SLS - Quasi.

In nearly permanent service combinations all variable actions are considered with their quasi-permanent values ѱ2 Fqk.

The following combinations are generated :

For more info on the SLS combination formulas above, please check the ABNT NBR 6118:2003 - 11.8.3 - Service combinations (Table 11.4). Additional info on partial safety factors may be found in 11.7.2 - Partial safety factors of actions at serviceability limit states (SLS).

Sonja Asselbergh

03/06/2012