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Concrete Design

FEM-Design is the most powerful FEM software for Concrete Design on the market. Design your beams, columns walls and slabs and even your connections in FEM-Design.
Read more about the functions under the function tabs at the right.

Axel Towers. Copenhagen

 

The RC Design module can do both code check and reinforcement auto design.
Bars can be designed for both 1st and 2nd order analysis. Nominal stiffness method and Nominal curvature method are both available.  
Utilization for the Section, stirrups, concrete, torsional reinforcement and crack widths are calculated.
The sections can be selected from the section database, or it can be customized in the section editor.
As output all design formulas are displayed, and design calculations is shown.

 

 

Both Walls and Plates are designed in the RC Module.

Choose between single or double layer reinforcement. Check the crack widths and the buckling resistance of the shells.

Punching capacity is calculated, and auto design is available for punching reinforcement design.

 

Punching without shear reinforcement

A concrete compression check on u0 is made according to 6.4.5 (6.53).
A concrete shear check on u1 is made for a capacity calculated according to 6.4.4 (6.47). 

Punching with shear reinforcement

A concrete compression check on u0 is made according to 6.4.5 (6.53).

Reinforcement is calculated with regard to critical perimeters u1 , u2 , ... u.nReinf according to 6.4.5 (6.52 ).
(ui are control perimeters above the reinforced region, distance between them is 'Perimeter distance', defined in the calculation parameter). 

A concrete shear check on uout is made for a capacity calculated according to 6.4.4 (6.47) (u.out is either the first perimeter that does not need reinforcement, or if it is not found, the perimeter that is k deff distance from the outer perimeter of the reinforcement).

 

Internal forces are calculated according to the occurrence of cracks.

Through iterations the load is applied, and crack locations are calculated. The stiffnesses in the cracked nodes are decreased for next calculation.
This method gives internal forces in the range between linear elastic and plastic.

This iteration method can be selected to load combinations, individually.

More info:

In FEM-Design a crack analysis technique is applied, where an iteration mechanism is calculating the effect of the cracks.
As the crack analysis is a non-linear calculation the principle of superposition is not true. By this fact the crack analysis is not applicable for load groups and the calculation has to be executed for every single combination. Generally the iteration is loading the structure in load steps, and modifies the stiffness of it in every step as more and more cracks occur during the loading process. The stiffness of the plate will be decreased only in the direction that is perpendicular to the crack lines, in the direction of the crack lines the stiffness remains the same as for the unracked state. The key of the calculation is the way the crack direction is calculated in a certain point. Dr. Ferenc Németh from the Technical University of Budapest has invented a method for this which is based on experiments. The cracked stiffness calculation is based on a conventional cross section modulus calculation of the second crack state which is combined with a Eurocode like crack distribution calculation (to consider the effect of uncracked parts of the plate between two cracks). The calculation for one combination is performed in the following steps:

  • Loading the structure with the loads of the combination and performing a linear calculation of the internal forces. 
  • Calculating the moment that cause crack on the structure in every points of the plate. This value is calculated by the tensional strength (limit stress) of the plate’s concrete material, the reinforcements are not taken into account at this point.
  • Searching for the place where the ratio of the crack moment and the actual (linear) moment has the smallest value. This value will describe the initial level of the load for the iteration. The size of a load step is calculated by user defined values. 
  • In the first step the initial load acts and is then increased by the calculated load steps. 
  • In every step is calculated weather the plate is cracked or not in a certain point (comparing the smallest principal moment to the crack moment of the plate). If the plate is cracked the direction of the crack is calculated and the stiffness of the cracked section. The element where the crack occures then will have reduced stiffness. In the next load step it will change the behaviour of the plate as the crack does in the real structure. 
  • When the full load is applied on the structure the calculation is continued with full load level to consider cracks occurring in the last load step and to have a stable result. This phase is called final iteration.

The final iteration is finished when the differences of the sum of the movements are less than a certain error percentage between two steps. The initial error percentage is 1% compared to the previous step, but this value could be adjusted.