What is the placement of concrete

How can the reinforcement in beams, ribs and columns be designed automatically?

1. Evaluation of the internal forces

Command: Concrete> Reinforced Concrete Design> 1D Members> Internal Forces

Before you start designing the reinforcement, you must check that the internal forces used in the design procedure are appropriate and logical in terms of size and distribution, and that they correspond to the assumptions of the model.

Fig. 1 Evaluation of the internal forces

2. Definition of a template for inserted reinforcement

Command: Concrete> Reinforced concrete design> Basic design data

When designing the reinforcement itself, you must first select a suitable reinforcement template. In the template, you specify the basic reinforcement (usually corner bars) that will be used over the entire length of the beam. In addition, you will define parameters for reinforcement that will be added in sections of the beam where the basic reinforcement is insufficient.

Fig. 2 types of defined reinforcement

  • As, basic = basic reinforcement
  • As, add = additional reinforcement
  • As, add, req = additional reinforcement required = the reinforcement that cannot be placed in the section with the template selected, which means that the template (actually the reinforcement layout) needs to be adjusted

In the reinforcement template you define the diameter of the reinforcing bars, their maximum number in one layer, the distance between stirrups, etc. The same approach applies to both the longitudinal and the shear reinforcement.

Fig. 3 Input of the defined reinforcement

3. Design and verification of the reinforcement provided

Command: Concrete> Reinforced Concrete Design> 1D Members> Reinforced Concrete Design

The program then uses the selected template to automatically place the reinforcement in individual beams and checks that the selected template is sufficient for all locations in the structure.

Fig. 4 Reinforcement value of the defined reinforcement shown as number and diameter (e.g. 2 ø 12 + 2 ø 16)

If the template is insufficient, the program will show the amount of reinforcement that needs to be added at the critical points (labeled As, add, req). In this case you have to adapt the reinforcement template and run the design again.

Fig. 5 Calculated value for the additional reinforcement

Unit verification value UC (As, req)

You can also check the adequacy of the template (i.e. whether it completely covers the required amount of reinforcement) with the Reinforced Concrete Design command by selecting the UC (As, req) values. This command calculates the ratio of the required and provided (template) reinforcement. The places where the template is insufficient (i.e. the places where the amount of reinforcement required is greater than the amount of reinforcement provided) are shown in red.

Fig. 6 Verification of the adequacy of the submission

Unit verification values ​​UC (As, max)

In addition, you can also check whether the reinforcement designed with the selected template corresponds to the structural requirements specified in the standard. To do this, select the UC values ​​(As, max) in the Reinforcement design command. This command compares the provided (template) reinforcement with the maximum amount of reinforcement to determine whether it complies with the detailed specifications specified in the standard.

Fig. 7 Review of the structural requirements

As already described above, this procedure also applies to the shear reinforcement.

4. Conversion of the inserted reinforcement into real 3D reinforcing bars

Command: Concrete> Reinforced Concrete Design> 1D Members> Reinforced Concrete Design
Action button: conversion into real bars

So far we have considered a certain number of bars with a certain diameter when designing the reinforcement. Individual reinforcing bars were not shown graphically in the 3D model. We can examine the moment diagrams, we can read off how many bars of which diameter are required at each point in the structure, but we cannot see the individual "real" reinforcing bars. To see them, we need to convert the provided reinforcement into 3D reinforcing bars (longitudinal bars and stirrups). This conversion takes place automatically and takes into account practical requirements such as the symmetry of the reinforcement above the supports, the minimum length of the bars, etc.

Fig. 8 Conversion of the inserted reinforcement into “real” 3D reinforcing bars

As soon as the reinforcement has been converted, we can not only display the reinforcing bars in the graphic window (and also in the calculation log), but also carry out a whole series of checks of the limit states for load-bearing capacity and serviceability.