DEL SISTEMA AMBIENTAL REGIONAL
VI. 1 Clasificación de las medidas de mitigación
See also: DESI
REIN
Item Description Unit Default
MOD Design mode LT SECT
SECT Reinforcement in cut BEAM Reinforcement in beam SPAN Reinforcement in span
GLOB Reinforcement in all effective beams
TOTL Reinforcement in all beams
RMOD Reinforcement mode LT SING
SING Single calculation
SAVE Save as minimum reinforcement SUPE Superposition with minimum re-
inforcement
ACCU Superposition with existing LCR reinforcement
ACSA Comb. ACCU and SAVE ACSU Comb. ACCU and SUPP
NEW New definition of the reinforce- ment distribution (for special cas- es only)
LCR Number of reinforcement distribution − 1 a negative value reinitializes all
ZGRP Grouping of prestressing tendons − 0 SFAC Factor for continuous reinforcement − 1.0
P6 Parameter for determining − *
P7 reinforcement − *
P8 (See notes) − *
P9 − *
P10 − *
P11 − 0.20
Item Description Unit Default
P12 − *
TITL Title of the design case LT 24 -
Any number of types of reinforcement distribution can be stored in the database. Under number LCR, the most recently calculated reinforcement for graphic de- pictions and for determinations of strain is stored. LCR=0 is reserved for the minimum reinforcement. This makes it possible, for instance, to design some load cases in advance and to prescribe their reinforcements locally or globally as defaults. The input value RMOD refers to the minimum and link reinforce- ment:
SING creates new LCR reinforcements using the given stored minimum re- inforcement
SAVE ignores the stored minimum reinforcement and overwrites it with the current reinforcement.
SUPE uses the stored minimum reinforcement and overwrites it with the possibly higher values of this run.
ACCU Superposition with existing LCR reinforcement ACSA Combination from ACCU and SAVE
ACSU Combination from ACCU and SUPP
There is also a control flagCTRLREIN, defining if the reinforcements should be increased or not. The latter to be used for the analysis of existing structures. Mit BEW BMOD ACCU LFB nnn kann man bis zu 255 Bewehrungsfälle als vorhandene Bewehrung für die aktuelle Berechnung aktivieren, gespeichert wird unter der letzten angegeben LFB-Nummer.
With REIN RMOD ACCU LCR nnn it is possible to add up to 255 reinforcement results as active reinforcement of this run. It will be saved with the last defined LCR entry
SUPE cannot be used during an iteration, since then the maximum reinforce- ment for an iteration step will not be able to be reduced. STAR2 therefore ig- nores a specification of SUPE, as long as convergence has not been reached. AQB can update or superpose the reinforcements at a later time: with REIN RMOD SUPE but without any DESI input.
A specification of BEAM, SPAN, GLOB or TOTL under MOD refers to interpolat- ed sections or sections with the same section number. For all connected ranges with the same section, the maximum for the range multiplied with SFAC is incor- porated as the minimum reinforcement. The design is done separately in each case for each load, however, so that the user can recognize the relevant load cases. 1 2 3 4 Section 1 SECT BEAM SPAN GLOB Section 1 Sect. 2
Figure 3.4: Distribution of reinforcements
As the existing reinforcement has a considerable impact on the shear design, AQB will perform an intermediate superposition after the design for normal force and bending moments. However, use of minimum reinforcement in ultimate load design has also a detrimental effect on the shear reinforcement, since the lever of internal forces is reduced. The user can take the appropriate precautions by specifying a minimum lever arm in AQUA.
Since this latter effect is especially strong with tendons, AQBS can give special effect to the latter in ultimate load design. This option is controlled with ZGRP:
ZGRP = 0 Tendons are considered with both their area and their pre- stressing. Normal reinforcement is specified at the minimum
percentage.
The relative loading capacity is found.
ZGRP> 0 Tendons are specified with their full prestressing, but with their
area (stress increase) only specified in so far as necessary. Normal reinforcement if installed only if the prestressing steel alone is not sufficient.
A required area of prestressing steel is determined.
ZGRP< 0 Tendons are specified with their prestressing, only specified in
so far as necessary, otherwise the same like ZGRP> 0.
If ZGRP< >0 has been specified, the tendons are grouped into tendon groups.
The group is a whole number proportion which comes from dividing the iden- tification number of the tendon by ZGRP. Group 0 is specified with its whole area, the upper group as needed. Any group higher than 4 is assigned group 4. The group number of the tendons is independent of the group number of the non-prestressed reinforcement.
Assume that tendons with the numbers 1, 21, 22 and 101 have been defined. With the appropriate inputs for ZGRP, the following division is obtained:
ZGRP 0 All tendons are minimum reinforcement
ZGRP 10 Tendon 1 is group 0 and minimum reinforcement Tendons 21 and 22 are group 2 and extra
Tendon 101 is group 4 and extra
ZGRP 100 Tendons 1, 21 and 22 are minimum reinforcement Tendon 101 is group 1, extra
An example of the effect can be found in Section 5.1.5.3. Notes: Parameters for determining reinforcement
The following parameters are not to be changed by the user in general:
Default Typical P7 Weighting factor, axial force 5 0.5 - 50
P8 Weighting factor moments -2 -2
When designing, the strain plane is iterated by the BFGS method. The required reinforcement is determined in the innermost loop according to the minimum of the squared errors.
F1 = P7 · (zm − zmn)P8 F2 = P7 · (ym − ymn)P8
The default value for P8 leads to the same dimensions for the errors. The value of P7 has been determined empirically. With symmetrical reinforce- ment and tension it is better to choose a smaller value, with multiple layers and compression a larger one. For small maximum values of the reinforce- ment the value of P7 should be increased.
Default Typical P9 Factor for reference point of strain 1.0 1.0 P10 Factor for reference point of moments 1.0 0.2-1.0 Lack of convergence in the design with biaxial loading can generally be attributed to the factors no longer shaping the problem convexly, so that there are multiple solutions or none. In these cases the user can increase the value of P7 or can vary the value of P10 between 0.2 and 1.0, for indi- vidual sections. In most cases, however, problems are caused by specify- ing the minimum reinforcement improper.
P11 Factor for preference outer reinforcement
Reinforcement which is only one third of the lever arm, is allowed to be maximum one third of the area of the outer reinforcement. P11 is the factor to control this. For biaxial bending P11=1.0, for uniaxial bending P11=0.0