GRP – Group Selection Elements

See also: SYST,PSEL,LC,GRP2

GRP

Item Description Unit Default

NO Group number − ALL

default ALL = all groups

VAL Selection LT _FULL

OFF The group is not used YES The group is used

FULL Use of group + result output LIN YES, but material linear

LINE FULL, but material linear (TH2, TH3 not affected)

FACS Factor for group stiffness / see also GRP2 STEA-QUEA

− -

PLC Number of the primary load case − * Default as in SYST

GAM Parameter of an additional kN/ m3 ₀

H analytical primary state m ₀

K − 1

SIGN σ_{-z = GAM·(Z-H) + SIGN} kN/ m2 ₀

SIGH σ_{-x =}σ_{-y = K · σ-z + SIGH} kN/ m2 ₀

FACL Factor of loads from primary stress PLC − 1 FACD Factor of dead weight in defined dead

weight direction (SYST GDIR from SOFIMSHA, SOFIMSHC)

− 0

FACP Factor of stress from primary load case PLC − FACL (FACT Temperature replaced by the record TEMP

from HYDRA)

HW Ordinate of the ground water level m _±99999.

GAMA Weight under water kN/m3 γ_-10

RADA Raleigh damping factor for mass proportion- al damping

1/ sec 0.

Item Description Unit Default RADB Raleigh damping factor for stiffness propor-

tional damping

sec _0.

MODD Modal damping factor − -

CS Construction stage for tendons − -

PREX Element prestress in local x direction kN, m ₀

PREY QUAD prestress in local y direction kN, m ₀

PHI Creep coefficient (see record CREP) − 0

EPS Shrinkage coefficient − 0

RELZ Relaxation of prestressing steel − 0 AUTO automatic determination

input 0.03 means loss of 3%

PHIF Creep coefficient for springs and foundation − PHI Creep coefficient for elements which do not

consist of concrete (composite structures)

PHIS − 0

T1 Stiffness development of elements with con- crete according to the modified concrete age T1

dys _-

HING Beam pin-joint temporarily for precast bridges

− ACTI

ACTI pin-joint

FIX fixed connection

example: Single Span Girder with Auxiliary Support

FACB Factor for bedding properties of the QUAD elements

− FACS

CSDL Dead load of a later construction stage − - MNO Material number of PHI and EPS if in a

group different materials occur →CSM

− -

The record GRP defines the participating elements as well as the stress state which is available at the beginning of the analysis. At first the defaults for all groups are defined with GRP ALL or GRP - , e.g. GRP -FULL. The following input for a group overwrites then this default, e.g. GRP 5 NO.

An input to GRP usually enforces a newbuilding of stiffness file $d1. It will also be unusable for further load cases. The storage of this stiffness file is possible with the record CTRL.

The group number of each element is obtained by dividing the element number by the group divisor GDIV (see SOFIMSHA/SOFIMSHC manual SYST..GDIV). The defaulted group selection is that one of the last analysis call or input block. Without any inputs all elements are used. With an input only the specified groups are activated.

If the subdivision of the elements occurs in groups, it should be kept in mind that the specification of the analytical primary state may require in certain cases a finer subdivision than the one assumed initially by the user.

GRP input without any group number set only the given parameters for the pre- vious defined groups. Example:

GRP 1,2

GRP CS 5 $ without group number $

Only the groups 1 and 2 are activated with CS 5.

A stiffness reduction may be defined with FACS for beams with calculation ac- cording to 2nd

/3r d

order theory (1/γm-multiple).

The values GAM-SIGH, FACT, HW and GAMA are only applicable to volume elements (BRIC), i.e. only then an analytical primary stress state is reasonable. By contrast, all control parameters of a primary state from a previous analysis have effect to all elements.

The processing of a temperature field from the program HYDRA was expanded essentially with the record TEMP. The input GRP FACT is not anymore permis- sible.

The primary state is necessary for non-linear analysis and in addition it facilitates the determination of loads due to changes of the static system. The analytical component is defined with the load SIGN which is effective in a height H and an increase GAM. The horizontal component is obtained by means of the lateral pressure coefficient and the vertical stress. The item GAM has usually the same values as the items GAM/GAMA of the material record, however, it is indepen- dent of them.

Figure 3.2: Analytical stress states

The loading components from the stresses of the primary state are multiplied by FACL to the load case which is to be calculated. FACD defines a dead weight loading with the values GAM/GAMA of the material record in dead weight direc- tion. This loading is usually in equilibrium with the primary state. The loads from FACL and FACD act in all load cases of the input block.

If the old loads of the primary load case ( PLC) are applied simultaneously to a system with the loads from the primary stresses with FACL=1, these both loading cancel themselves. New deformations do not result. Therefore the loads from the primary stresses oppose the old loads.

The item HW specifies the phreatic level in the corresponding group. Contin- uum elements (BRIC) located below HW are analysed under buoyancy. The default setting fo HW is "infinitely deep". Depending on the direction of gravity the phreatic level is set to ±99999m, in this case.

The analysis of the tendons is controlled by CS similar to the program AQBS. Depending on the value of CS the empty duct or the duct with the tendon or of the grouted duct are used. If CS is not input, tendons are used with CS 998 (=bonded, if not ICS1=999 in TENDON for unbonded tendons). More explana- tions see prestressed_slab.dat

Prestress of elements via record GRP: GRP - PREX PREY

In the program SOFIMSHA/SOFIMSHC a prestress which is considered during the calculation of stiffness can be input only at TRUS-CABL-SPRI.

With GRP ... PREX PREY a real prestress can be defined in addition to TRUS- CABL-SPRI also for QUAD and BEAM elements. This acts, first of all, as a normal prestressed load. However, it is considered also with the factor CTRL PRES for the initial stiffness. In this way membrane and cable structures can be calculated more simply according to the third-order theory. A membrane high

point should be input via the record HIGH.

The value from GRP ... PREX PREY is interpreted in kN/m for QUAD, and in kN for BEAM, TRUS, CABL and SPRI.

The GRP prestress acts also for linear calculation. A stabilization for the er- ror estimate can be achieved in this way at displaced systems. In addition the prestress is considered also for an eigenvalue determination!

Differences of the input of a truss or cable prestress in the program SOFIMSHA/- SOFIMSHC for the GRP prestress:

- PRE acts in all load cases as long as a primary load case (PLC) is not used. - GRP-PREX acts only in ASE calculations in which it is input, however, in the

record GRP in addition to a prestress of a primary load case. Creep for composite systems concrete + steel

A separate item PHIS can be input in the record GRP for elements which do not consist of concrete. Elements of concrete are processed with GRP ... PHI,EPS. Springs, boundary elements and elastic foundations are processed with GRP ... PHIF without shrinkage. Elements whose cross section material is not concrete are processed with GRP ... PHIS. Shrinkage of these elements is considered with the value EPS·PHIS/PHI.

For BEAM composite cross sections and BEAM prestressed concrete cross sec- tions creep and shrinkage have to be processed with the program AQB.

The prestressing steel relaxation of the QUAD tendons is determined automat- ically with the input RELZ AUTO in combination with the time duration input T in record CREP. The material values STEE ... REL1+REL2 from the program AQUA are used..

Stiffness development of elements with concrete

For input of the temperature adjusted concrete age T1 in GRP...T1, the devel- opment of stiffness of concrete elements is taken into account. The program CSM (version 11.57) automatically adjusts T1 in dependence on the given tem- perature. The development is plotted for the first concrete material (for ECHO

MAT FULL for all concrete materials and also for calculations with primary load case).

Temporary BEAM pin-joints can be fixed with GRP HING FIX. Thus a construc- tion stage can be calculated with pin-joint and a final stage without pin-joint. The results can be superpositioned and designed. All pin-joints are active with the default GRP HING ACTI.

Example see ase6_two_span_girder_construction_stages.dat Later construction stages

With GRP CSDL the dead load of a later construction stage can be activated already for composite beam cross sections with activated stiffness of the cross section construction stage CS (green concrete dead load).