Definition of the Reinforcement (Reinforcement Poi- 123docz.net

Group 1 General) is taken for ordinary stress check as well as for stress checks for pre-stressing tendons (action FIBCHK and

3.3.5 Definition of the Reinforcement (Reinforcement Points)

The term „reinforcement“ used in this section indicates the longitudinal reinforcement carrying the forces induced by bending moment and normal force. The required input data for the shear reinforcement is described in section 3.3.8.

In order to specify the reinforcement of a reinforced concrete structure or to prepare the determination of the required reinforcement by the program, the user has to perform following tasks:

1. Definition of the Reference point groups in "PROPERTIES #ADDGRP 2. Setting the required Reference Points in "PROPERTIES #CS !ADDPNT 3. Definition of the fixed and the variable reinforcement in "STRUCTURE

#ELEMENT !REINF.

3.3.5.1 Reference point groups for the reinforcement (Reinforcement Groups) Reference point groups related to reinforcement points are also called Reinforcement Groups. The definition of “Reinforcement Groups” is the main application field for Reference Point Groups. The purpose is to distinguish the various reinforcement layers related to different stress distribution states. This can not be done by using the Refer- ence Point types description. The types only describe the distribution of the reinforcement in the cross-section (e.g. concentrated in a single point, distributed over a line or even over a given perimeter).

Attention: It is not allowed to mix point reinforcements and line reinforcements in the same group, because no proper distribution of the whole rein- forcement is possible in this case. RM2000 does not check if point and line reinforcements are mixed up in the same group! The calcu- lation is done with an un-controlled distribution.

The Stress Limit Group is not used in this case and needs not to be defined for Refer- ence Point Groups specifying a Reinforcement Group.

3.3.5.2 Specifying the required Reference Points (reinforcement points)

The Reference Points for the definition of the reinforcement describe the position of the reinforcement in a cross-section. The Reference Point Type (REIPSI, REIPOB, REIPOM, REIPOE or REICUM; see chap. 3.3.4) assigned to the different points, only defines the distribution of the reinforcement in the CS.

The Reference Points belonging to the considered Reinforcement Group have to be defined at the start and end cross-sections of the element to enable the assignment of a reinforcement to an element. It is therefore recommended to define all reinforcement points in all cross-sections of a continuous element series, even if some reinforcement layers are not needed in a certain section of the superstructure.

3.3.5.3 Specifying the reinforcement in an element

The assignment of the actual reinforcement values to the elements is done in

"STRUCTURE #ELEM !REINF. The different Reinforcement Groups are automati- cally assigned to the elements, using the specified reinforcement points at the start and end cross-sections of each element.

Per default all reinforcement areas are set to 0. A specific amount of reinforcement can be assigned to a certain group by modifying the related line in the Reinforcement Groups table (lower list in the "STRUCTURE #ELEM !REINF pad).

For each assigned Reinforcement Group can be defined:

• Whether it is allocated throughout the entire length of the element or just over a part of it

• whether the total reinforcement is split up in a constant and a variable amount (button “variable”) or fixed by as a constant value (button “fix”)

• a fixed amount A1 (cross-section area of the reinforcement)

• an additional amount A2, fixed or variable – depending on the button

“fix/variable”

When pressing the “Modify”-button an input pad appears, asking:

% El-from First element of the series

% El-to Last element of the series for the reinforcement definition

% El-step Element step within the series

# Fix Both reinforcement areas (A1 and A2) are fixed

# Var Only A1 is fixed, A2 is variable

% Group Name of the Reinforcement Group (can be selected in the pull- down-menu)

% X1/l Start point of the reinforcement in the element (default : 0.0)

% X2/l End point of the reinforcement in the element (default: 1.0)

% A1 Fixed amount of the reinforcement

% A2 Variable (or another fixed) amount of the reinforcement as described in the precedent paragraph

The total reinforcement area is always equally distributed to the different parts of the Reinforcement group (i.e. for point reinforcements to all points, for line reinforcements to the total length of the line reinforcements).

The button “fix” is generally used if no additional reinforcement in this group is allowed. The value A2 = 0 is then never changed. In case of a variable value A2 the design module of RM2000 increases the value until the Ultimate Load Check indicates the required safety.

Note: After a design action the user can change the button from “variable” to “fix” in order to avoid a further increase of A2.

If more than one Reinforcement Groups with a variable reinforcement A2 exist, the program increases the reinforcement (during the design action) independently from each other. RM2000 always tries to reach a minimum of total necessary reinforcement. In general therefore the reinforcement with the largest distance from the neutral axis will be increased. If more layers of reinforcement are intended to be increased at the same time (e.g. for special symmetric reinforcement) they must be grouped together in one Reinforcement Group. A facility for prescribing a special sequence for increasing the different reinforcement layers (possibly up to a certain limit value) is actually not yet implemented in the program.

A reinforcement area A2 once calculated for a certain loading state is taken into consid- eration in later design actions for other loading states. If this effect is not desired the user has the choice to add the action ReinIni in the Construction schedule to re-initialise A2 and set it to the value 0 before .

3.3.5.4 Example 1: “Box girder”

2 separate reinforcement layers (distributed over a line) are applied in this example on the top and on the bottom of the box girder.

2 Reference Point Groups (REINF-BOTTOM, REINF-TOP) are therefore specified.

Each Reinforcement Group consists of two reinforcement points (REIPOB...start point of the polygon, REIPOE...end point of the polygon). The names can be chosen ad libitum (here RTL...reinforcement top left, RTR...reinforcement top right, RBL...reinforcement bottom left, RBR...reinforcement bottom right).

3.3.5.5 Example 2: Rectangular cross-section

Example a: uni-axial design Example b: bi-axial design

nae: RTL group: REINF-T type: REIPOB

group: REINF-L type: REIPOB

Two and four Reinforcement Groups are defined in this example (REINF-TOP, REINF- BOTTOM, REINF-LEFT, REINF-RIGHT). Each group consists of two reinforcement points (REIPOB...start point of the polygon, REIPOE...end point of the polygon). The names can be chosen ad libitum (here RTL...reinforcement top left, RTR...reinforcement top right, RBL...reinforcement bottom left, RBR...reinforcement bottom right, etc.). The points in the corners (e.g. RBR and BRU) may have the same position (same coordinates), but they must have different names. It is not possible to assign more than one reference group to the same point.

3.3.5.6 Example: Column

This example gives an idea how to place a Reinforcement Group (REINF) in a circular cross-section. This group is described by nine reinforcement points (REIPOB...start point of the polygon, REICUM…intermediate points of the polygon, REIPOE...end point of the polygon). The names can be arbitrarily chosen (R1-R9). Because of the fact that the same group is assigned to all points, the design module will determine a uni- formly distributed reinforcement.

Definition of the Reinforcement (Reinforcement Points)

Properties used for Creep Analysis and Time Dependency

Characteristic Lines for the Shear Capacity Check