Design of Reinforced Concrete Structures

Construction site visit 07. Nov. 2019at Budapark Project by Kopaszi dam

The construction details of the floor above ground floor level of one residential building and the trench space view of

the neighbouring office building was shown to us by the representative of the general constructor firm Market

Construction Co. Balázs Csernyak.

On the photo below in the foreground the reinforcement of the rc floor is being mounted. To the left the concrete

has already been poured on it (you see the fresh concrete reflecting another building almost ready.

The fresh concrete's side pressure is supported by a plastic mesh. Orange tubes containing electricity wires

distributed from a central vertical shaft are placed upon the bottom mesh reinforcement of the rc slab. Below the

bottom reinforcement you see white-grey plastic tubes, in which circulation of hot (or during summer cold) water

will serve ceiling heating or cooling respectively. The execution project of the floor construction is, accordingly,

common job of the architect, the structural engineer, the electric engineer and of the installation engineer.

The photo above taken from the terrace shows the way of separation of the interior and exterior by means of stone

wool insulation (below the red strip). The anticorrosion steel bars – designed both for moment (top bars) and shear

(bent down bars from interior to exterior) intersect the thermal insulation.

Staircase and elevator shafts surrounding rc walls – which are the main contributors to the spatial rigidity of the

building – were constructed in advance by use of liftform technology (climbing formwork). You see the strips of

holes on it with the elements of reinforcement passing through, which serve the junction of the floor slabs to be

constructed upwards.

Inside the staircase and elevator block the internal partially prefabricated rc partition walls – double side cca 8 cm

thick prefab walls with protruding reinforcement into the cavity in between – so called ,,pocket walls,, are seen on

this photo on the 1st storey level, before concreting the interior cavity of the pocket walls. The opening on left is the

space for the stair flights, which are again prefabricated and will be placed later.

The main structural problem of rc flat slab floors is the punching (shear failure) of the slab around the column head.

Because of the very intensive reinforcement designed for negative moment above the column, there is restricted

possibility to place the shear reinforcement there designed against punching. One up-to-date solution of the

problem is to place double-headed steel dowels in position as seen on this photo. The inclined cracks due to shear

intersect the axis of the dowels which work in tension and are anchored at both top and bottom ends in the

concrete. The dowels are to arrange around the column head in circles. No. and spacing of circles, diameter and

spacing of dowels along the circles are parameters to be designed. because of technical reasons dowels are

interconnected by straight steel strips by welding, and arranged in radial directions with respect to the circles.

The neighbouring office building will have three underground levels. On the photos above -2 and -3 levels can be

seen. The trench space is surrounded by slurry walls, tied back by prestressed steel tirants anchored along the -2

level part of the wall. The excavation of the -1 level was made with inclined surrounding earth walls, stabilized by

shotcreting (see on photos to come!).

In the right corner the placement of the formwork of the floor above -3 level is shown.

Further to left you see mounting of the reinforcement and formwork of rc columns and perimeter walls (inside the

slurry wall). In the background the columns have already been concreted and their formwork removed.

More further to left direction you see the protruding part above the soil of the pile foundation. 4 to 4 piles will

support one rc column. The top of 4 piles are united by one rc pile head. which will support one rc column in the

middle. Placing of the concrete into one of the pile heads is just going on the next photo.

The pile head to the left had already been concreted. Formwork for the 2nd phase of concreting is still seen on the

photo.

The photo below shows formworks on walls and columns in the background and one ready-made wall in front with

the removed formwork leaning to the wall

It is a pity that only one third of the group was present on the construction site visit

András Draskóczy