Analysis of building framework from monolithic reinforced concrete and its principal bearing elements

Design model of the structure represents monolithic framework that contains walls, columns, slabs and beams. Foundation is the monolithic slab on piles (bored piles). The structure represents two 25-storey sections that are supported with stylobat 2-storey part. Both static and dynamic loads (appropriate to local building codes) are applied to design model

Description

‘Alter Ego’ – the premium class multifunctional housing estate (underground parking, fitness centre, swimming pool, restaurants) located in Kiev centre. Total area of housing estate is 55 000 m2.

Design model

Design model represents 3D shell-bar FE model. Model generation and analysis of stress strain state were carried out in MONOMAKH-SAPR software. 3D framework of the structure was generated in BUILDING module of MONOMAKH-SAPR program. Elements of the framework were designed in modules SLAB, WALL, COLUMN and BEAM.

According to design input, two design models were generated. They differ in a special design feature of floor slabs:

first variant - framework with slabs of thickness 0.28m with void fillers and class of concrete B35;
second variant – solid monolithic slabs 0.22m and class of concrete B35.

Design model of the monolithic floor slab with void formers was generated in LIRA-FEM software. 3D model was generated in graphical environment of VISOR-SAPR module, the stiffness parameters of bars were computed in the Cross-section Design Toolkit module of LIRA-FEM program.

To ensure optimal behaviour of the building framework, different classes of concrete were used in vertical elements: concrete of lower classes is used at the upper stories of the building (from B60 to B30).

Peculiar features

In model simulation process, two basic requirements of the customer were implemented:

First – to carry out strength analysis of foundation slab and design it without construction joints. It was justified by complexity in generation of foundation slab. Analysis was carried out using NL Engineering system (NonLinear Engineering Design), so nonlinear behaviour of concrete and reinforcement are considered.

Second – to carry out analysis of structure with void formers in floor slabs and analysis of structure with solid floor slabs; then to draw conclusions as to effectiveness of each option.

Stiffness of the slab with the void formers was computed for its characteristic parts. In this case, the mutual influence of the vertical and horizontal elements of the framework was taken into account. Solids, plates and bar finite elements (FE 32) were used during generation of models of floor slabs.

To determine the most adequate design model of the floor slab with void formers, several design models were generated:

with plate elements (FE 42, 44);
with solids (FE 32, 34, 36);
with bar elements (stiffness is computed in Cross-section Design Toolkit module of LIRA-FEM program);
with bar and plate elements (stiffness is computed in Cross-section Design Toolkit module of LIRA-FEM program).

With MONOMAH-SAPR and LIRA-FEM software packages it was possible to completely solve such problems.