Diagrams (Concrete Beam)

Last modified by Fredrik Lagerström on 2021/05/17 08:11

The Diagrams menu option makes it possible to have calculation results shown graphically. The user will find the following options under Diagrams: Bending Moment and Shear, Reinforcement-Layout, Section marking, Curtailing and Deflections. These are described in the following passages:


Bending moment and shear force

The Bending Moment and Shear option will be available when the elastic analysis or plastic design (Danish Annex) calculation is finished.


Diagrams of moment and distribution of shear force can be obtained here, when variable loads are present, maximum values considering all load combinations are shown.


The Reinforcement-Layout will be available when the design calculation is completed.


The option displays a detailed presentation of total longitudinal- and stirrup reinforcement due to an elastic or plastic design. The layout can also apart from bending and shear, be dependent on possible crack width- or deflection criteria in the serviceability limit state as well as of the user’s manual increase or decrease.

The above picture shows a number of bars and required lengths for bending reinforcement. The user can act on this result with the Curtailing options.

A picture showing the cross-section, and the placement of reinforcement in that section, will be obtained by placing the arrow in a suitable position and double click. A maximum of 80 sections for the whole beam can be defined. A section is marked/cleared by double clicking with the track point exactly on the section. A single click shows cross-section at a previous marked section. All marked sections can also be obtained from the printer. A desired section can also be obtained with the Section marking option.

Section marking


The Section marking option shows the Cross-section dialog box in which the user can state the distance to desired section counted from the left end of the beam.

The cross section and the placing of the reinforcement in this section are shown as in the picture below.



The Curtailing option is available when the design calculation is finished.

The initial position

Initially, after design calculation, all bottom reinforcement continues to the supports and all top reinforcement at support continues to the point where the tensile force is zero. This means that the user, initially, has a pretty acceptable solution of anchorage of reinforcement. It is however up to the user to do further checks depending on active concrete code demands. If the initial situation is sufficient the user will not have to worry about curtailing.
In many cases there is a good deal to be earned by trying to minimize the length of the bars. The user can easily and illustratively adapt the length of the included bars to the current conditions with some help from the Curtailing option.
Not all of the bars is possible to curtail. According to code practice in some active concrete code at least a required part (x%) of the bottom reinforcement shall continue to and past the supports, and that at least a required part (y%) of top reinforcement at support shall continue to and past the point where the calculated tensile force is zero. Here x = y = 25% is used. A three span beam that is rigidly connected to the left and hinged supported to the right might for example look as seen below.


Maximum tensile force curve (1) and corresponding displacement of the tensile curve (2) according to [1] (20) are shown above. At (3) is shown the inclined resisting tensile curve that represents each bar with consideration to its required anchorage length. To establish an approved anchorage the diagram of resisting tensile force (3) must always be outside the displaced curve of the tensile force due to maximum moment. It is up to the user to see to that this is  he case.

Curtailing of the bars

Curtailing of the bars can be done either layer by layer or bar by bar, see 2.3.5. The bars can be black, blue or green when they are shown on the screen. The black bars represent the minimum required part of reinforcement as described in, which means that the bars can’t be curtailed. The bars at the hinged support must be drawn a little bit past the theoretical point of support, as seen in the above picture. Any remaining bars in the layer, where the minimum required part of reinforcement situated, are represented in blue, the next layer in green after which the following layer is blue again and so on.
It is advantageous to use the zooming possibilities in the program when changing the length of the bars. In order to change the length of a bar, place the mouse pointer (1) on it, hold down the left button and move the pointer to the intended position as shown below.


As mentioned earlier it is important to make sure that the inclination of the diagram of the resisting tensile force at all times are outside the displaced curve of the tensile force in order to obtain an acceptable anchorage.


An attempt to try and adapt the bar lengths to the displaced curve of the tensile force for the whole beam can for example look as below.


The result of the performed curtailing can be closer viewed with some help from the Reinforcement-Layout option, see above. When the file is stored the current situation of the curtailing will be stored. A new design can be executed when wanting to go back to the initial values.


The Deflections option will be available after the Serviceability Limit State calculation.

The deflection curves are drawn for beam with un-cracked sections loaded with total load as well as for beam with cracked sections loaded with total load and long-term (quasi-permanent) load in the Serviceability Limit State.