Inappropriate design 41
an accumulated level difference mounting up to several centimeters can
occur at the highest floor levels (Figure 2.10). Although the stability of the
tall building will not be in danger, slightly inclined floors can make it very
uncomfortable to live or work at the highest floor levels.
2.5 InaPProPrIate MIx DesIgn
Design errors can also be made on the level of the concrete composition.
An inappropriate selection of the required concrete type can be made, not
duly considering the environmental aggressiveness. Or, in the case when
the right concrete type has been selected, the detailed mix design can still
be unsatisfactory. Both aspects will be explained in the following sections.
2.5.1 Inappropriate selection of concrete type
A good and durable concrete should be selected carefully considering the
potential actions of the environment (e.g. frost, chlorides, carbonation, sulfates; see also Chapter 1). In most cases, the appropriate consideration of
environmental actions and the subsequent selection of adequate concrete
type is well-known and does not pose significant problems in concrete
practice. However, there are situations where the appropriate selection of
required concrete type in order to guarantee a durable structure is somewhat
less obvious. Typical cases leading to repeated mistakes are swimming pools.
Shrinking and creeping
Concrete core
Accumulated level difference ∆
Steel skeleton
Figure 2.10 Effect of concrete core creep and shrinkage in tall buildings.
an accumulated level difference mounting up to several centimeters can
occur at the highest floor levels (Figure 2.10). Although the stability of the
tall building will not be in danger, slightly inclined floors can make it very
uncomfortable to live or work at the highest floor levels.
2.5 InaPProPrIate MIx DesIgn
Design errors can also be made on the level of the concrete composition.
An inappropriate selection of the required concrete type can be made, not
duly considering the environmental aggressiveness. Or, in the case when
the right concrete type has been selected, the detailed mix design can still
be unsatisfactory. Both aspects will be explained in the following sections.
2.5.1 Inappropriate selection of concrete type
A good and durable concrete should be selected carefully considering the
potential actions of the environment (e.g. frost, chlorides, carbonation, sulfates; see also Chapter 1). In most cases, the appropriate consideration of
environmental actions and the subsequent selection of adequate concrete
type is well-known and does not pose significant problems in concrete
practice. However, there are situations where the appropriate selection of
required concrete type in order to guarantee a durable structure is somewhat
less obvious. Typical cases leading to repeated mistakes are swimming pools.
Shrinking and creeping
Concrete core
Accumulated level difference ∆
Steel skeleton
Figure 2.10 Effect of concrete core creep and shrinkage in tall buildings.