EN$2400$ Structural Analysis and Design

DESIGN SHORT $4-$ ANALYSIS AND DESIGN OF A STEEL AND CONCRETE INFILL

ERAME

The owner of a building complex has planned to infill the space between two existing adjacent buildings with a new multi$-$bay single storey building and roof garden. The new $30-$metre long structure will comprise frames at $5m$ centres that support a pre$-$cast concrete roof deck. A cross$-$section through one of the internal frames is shown in Figure $4\mathrm{.}1.$ The variable load to be supported by the roof deck has been calculated to allow for a garden area and a set of light$-$weight free$-$standing structures. You are required to design both an internal concrete frame and a steel frame to support the roof structure and associated loads, assuming that both frames are continuous structures.

You should undertake a series of analyses by hand using the stiffness$-$based matrix method. Details of the analysis cases to be considered are given on page $2$ of this design brief. You should NOT undertake a computer analysis of these frames.

You are required to provide full calculations and sketches to support your answers.

You should assume the following:

The roof deck comprises $250$ thick precast concrete units that span between the frames, overlaid with a $50mm$ mortar screed. The total characteristic permanent load of the units and screed is $5k\frac{N}{m^2}.$

The characteristic variable load is $7\mathrm{.}5k\frac{N}{m^2}.$

The beams are pinned at their intersection with the existing buildings.

The existing buildings have structural elements capable of supporting the beam loads at the necessary locations.

The columns are supported by an existing raft foundation located $1000mm$ below the finished floor level $($FFL$)$ of the new structure.

There are pinned supports at the base of the columns.

The beam$-$column connections should be considered continuous $($i$.$e$.$ moment carrying$).$

All dimensions are in mm$.$

Figure $4\mathrm{.}1.$ Cross$-$section through an internal frame