Titel_SS06

Poor construction procedures

Inadequate connection elements

Inadequate load behavior

Unclear contract information

Contravention of instructions

Unforeseeable events

Errors in design calculations

Reliance on construction accuracy

Complexity of project system

47

42.2

23.5

21.8

7.1

2.5

1.8

1.2

0102030405060

Primary causes of structural failure

Frequency (%)

54.3

Figure 1.11: Illustration of primary causes of structural failures (Stewart and Melchers (1997)).

It is seen that the major contributors are poor construction procedures, inadequate connecting
elements and inadequate load behaviour.

In Figure 1.12 the relative distribution of reasons for the failures and errors is illustrated. It is
seen that neglected risks and risks treated with false and insufficient measures dominate the
picture when all incidents are considered. It should also be noted that a relatively large part of
the failures and errors represent risks, which were accepted. As regards failures and incidents
leading to damage costs, loss of lives and injuries, these are dominated by neglected risks and
risks treated by false measures. In the latter cases the accepted risks contribute by a clearly
smaller percentage.

0

20

40

60

80

100

Neglected

Wrong measures

Neglected and wrong

Insufficient

Accepted risk

Not known

10

16

22

26

4

22 27

8

8

12

25

(^2030)
(^36)
29
22
10
All cases
723
Cases ofdamage
723
Cases withinjuries
(^63)
Figure 1.12: Illustration of the relative distribution of causes of failures and errors (Matousek and
Schneider (1976)).
In Figure 1.13 the relative distribution of when in the phases of the projects risks were not
adequately treated. It is seen that most of the failures and errors take origin already in the
planning and execution phases. The failures and errors with economic consequences
predominantly originate in the planning phase and in the failures and errors leading to loss of
lives and injuries in the execution phase.