Snow removal analysis
Snow removal – general concept
The aim of this investigation is to determine
o Under which snow load conditions the structure remains
A safe and usable: respects safety concept required by the codes
B stable:
but no longer in accordance with the required safety coefficient
o When it is necessary to remove snow from the roof in order to
A use the stadium in winter:
optional (not obligatory)
B avoid overload of the structure:
obligatory (allowable snow load exceeded)
o Where to remove snow in order to reduce the utilization of the structure
o Give a guideline of scenarios and related actions to be taken
o Describe a possible strategy for the snow removal
Snow removal – general concept
The underlying safety concept is as follows:
A In order to use the
stadium the snow load must
be kept under the allowable
characteristic snow load. In
order to ensure such
situation it is recommended
to start a removal before the
value is reached.
B In order to avoid a critical
situation the snow load
must never exceed the
Ultimate Limit Load. In order
to prevent such situation all
snow above the
characteristic allowable
snow load shall be
removed.
Increase of acceptable snow load in case of partial snow removal
Scenario 1
Within the analysis it
has been shown that:
Scenario 3
[kg/m2]
Scenario 4
increase of capacity for remaining roof
130
The effect of snow
removal decreases with
the distance to the
centre of the stadium:
capacity
120
110
scenario 1 + 3
100
scenario 1
90
-> close to needle:
big positive effect
scenario 1 + 3 +
4
80
70
-> close to
Compression Ring:
almost no effect
60
evacuated area [m2]
50
0
5000
10000
15000
20000
25000
Snow removal strategy – naming of areas
4
3
1
2
Snow removal strategy – A – criteria of usability
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
exceeded
in last 40
years
main roof
rest
< 72 kg
< 72 kg
< 72 kg
< 72 kg
< 72 kg
Usable
safe (1.5)
8
0
< 92 kg
< 92 kg
< 92 kg
< 92 kg
Usable
safe (1.5)
3
0
0
< 100 kg
< 100 kg
< 100 kg
Usable
safe (1.5)
3
0
0
0
< 108 kg
< 108 kg
No use
safe (1.5)
1
0
0
0
0
< 115 kg
No use
safe (1.5)
1
Snow removal strategy – A – criteria of usability
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
exceeded
in last 40
years
main roof
rest
< 72 kg
< 72 kg
< 72 kg
< 72 kg
< 72 kg
Usable
safe (1.5)
8
0
< 92 kg
< 92 kg
< 92 kg
< 92 kg
Usable
safe (1.5)
3
0
0
< 100 kg
< 100 kg
< 100 kg
Usable
safe (1.5)
3
0
0
0
< 108 kg
< 108 kg
No use
safe (1.5)
1
0
0
0
0
< 115 kg
No use
safe (1.5)
1
max 72kg
Snow removal strategy – A – criteria of usability
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
exceeded
in last 40
years
main roof
rest
< 72 kg
< 72 kg
< 72 kg
< 72 kg
< 72 kg
Usable
safe (1.5)
8
0
< 92 kg
< 92 kg
< 92 kg
< 92 kg
Usable
safe (1.5)
3
0
0
< 100 kg
< 100 kg
< 100 kg
Usable
safe (1.5)
3
0
0
0
< 108 kg
< 108 kg
No use
safe (1.5)
1
0
0
0
0
< 115 kg
No use
safe (1.5)
1
max 92kg
Roof in garage
Snow removal strategy – A – criteria of usability
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
exceeded
in last 40
years
main roof
rest
< 72 kg
< 72 kg
< 72 kg
< 72 kg
< 72 kg
Usable
safe (1.5)
8
0
< 92 kg
< 92 kg
< 92 kg
< 92 kg
Usable
safe (1.5)
3
0
0
< 100 kg
< 100 kg
< 100 kg
Usable
safe (1.5)
3
0
0
0
< 108 kg
< 108 kg
No use
safe (1.5)
1
0
0
0
0
< 115 kg
No use
safe (1.5)
1
snow removed
max 100kg
Snow removal strategy – A – criteria of usability
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
exceeded
in last 40
years
main roof
rest
< 72 kg
< 72 kg
< 72 kg
< 72 kg
< 72 kg
Usable
safe (1.5)
8
0
< 92 kg
< 92 kg
< 92 kg
< 92 kg
Usable
safe (1.5)
3
0
0
< 100 kg
< 100 kg
< 100 kg
Usable
safe (1.5)
3
0
0
0
< 108 kg
< 108 kg
No use
safe (1.5)
1
0
0
0
0
< 115 kg
No use
safe (1.5)
1
snow removed
max 108kg
Snow removal strategy – A – criteria of usability
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
exceeded
in last 40
years
main roof
rest
< 72 kg
< 72 kg
< 72 kg
< 72 kg
< 72 kg
Usable
safe (1.5)
8
0
< 92 kg
< 92 kg
< 92 kg
< 92 kg
Usable
safe (1.5)
3
0
0
< 100 kg
< 100 kg
< 100 kg
Usable
safe (1.5)
3
0
0
0
< 108 kg
< 108 kg
No use
safe (1.5)
1
0
0
0
0
< 115 kg
No use
safe (1.5)
1
snow removed
max 115kg
Snow removal strategy – B – criteria of characteristic resistance
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
Events in
last 40
years
main roof
rest
< 108 kg
< 108 kg
< 108 kg
< 108 kg
< 108 kg
No use
LIMIT (1.0)
1
0
0
< 150 kg
< 150 kg
< 150 kg
No use
LIMIT (1.0)
0
0
0
0
< 160 kg
< 160 kg
No use
LIMIT (1.0)
0
Snow removal strategy – B – criteria of characteristic resistance
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
Events in
last 40
years
main roof
rest
< 108 kg
< 108 kg
< 108 kg
< 108 kg
< 108 kg
No use
LIMIT (1.0)
1
0
0
< 150 kg
< 150 kg
< 150 kg
No use
LIMIT (1.0)
0
0
0
0
< 160 kg
< 160 kg
No use
LIMIT (1.0)
0
Limit 108kg
Snow removal strategy – B – criteria of characteristic resistance
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
Events in
last 40
years
main roof
rest
< 108 kg
< 108 kg
< 108 kg
< 108 kg
< 108 kg
No use
LIMIT (1.0)
1
0
0
< 150 kg
< 150 kg
< 150 kg
No use
LIMIT (1.0)
0
0
0
0
< 160 kg
< 160 kg
No use
LIMIT (1.0)
0
snow removed
Limit 150kg
Snow removal strategy – B – criteria of characteristic resistance
1
retractable
roof
2
glass roof
3
main roof
area 3
4
main roof
area 4
A
usablility
B
Structural
integrity
Events in
last 40
years
main roof
rest
< 108 kg
< 108 kg
< 108 kg
< 108 kg
< 108 kg
No use
LIMIT (1.0)
1
0
0
< 150 kg
< 150 kg
< 150 kg
No use
LIMIT (1.0)
0
0
0
0
< 160 kg
< 160 kg
No use
LIMIT (1.0)
0
snow removed
Limit 160kg
Snow removal strategy –
A – in order to maintain usability (optional)
B – in order to ensure structural integrity (mandatory)
Snow load
A provisions to maintain full usability
B consequences to avoid critical situation
0-50 kg/m2
no action
no action
50-72 kg/m2
snow removal at retractable roof + glass roof
no action
72-100 kg/m2
No use
Removal at retractable roof and glass roof
100-115 kg/m2
No use
Removal at retractable roof and glass roof and
main roof from Glass roof til rockers
snow load as per 50 year return period (code)
Note:
This table gives the recommended actions to be taken. The benchmarks for
the usability criteria A are set with a distance to the allowable limits in order to
provide enough time for the snow removal.
The actions B are mandatory.
Snow removal strategy –
Q
zima
Evaluation of the proposed
strategy for last 40 years
50 - 72 kg/m2
72 - 100 kg/m2
snow removal
inner glass area 3 area 4
roof
roof
can evacuate
recommended to evacuate
>100 kg/m2
must evacuate
data wystąpienia maksymalnej wartości maksymalna
cięŜaru pokrywy
wartość cięŜaru pokrywy
criteria
rok
1971/1972
1972/1973
1973/1974
1974/1975
1975/1976
1976/1977
1977/1978
1978/1979
1979/1980
1980/1981
1981/1982
1982/1983
1983/1984
1984/1985
1985/1986
1986/1987
1987/1988
1988/1989
1989/1990
1990/1991
1991/1992
1992/1993
1993/1994
1994/1995
1995/1996
1996/1997
1997/1998
1998/1999
1999/2000
2000/2001
2001/2002
2002/2003
2003/2004
2004/2005
2005/2006
2006/2007
2007/2008
2008/2009
2009/2010
2010/2011
miesiąc
1972
1
1973
1
1974
1
1975
1
1976
1
1976
12
1978
2
1978
11
1980
1
1981
1
1981
12
1983
2
1983
2
1984
2
1985
3
1986
2
1987
1
1988
2
1988
12
1989
12
1991
2
1991
12
1991
12
1993
3
1993
11
1995
1
1996
3
1996
3
1997
2
1998
2
1999
2
1999
12
2001
3
2002
1
2003
2
2004
1
2005
3
2006
2
2006
2
2007
1
brak Q (pokrywa 4 cm)
2009
2
2010
2
2010
12
2
dzień
[kN/m ]
31
30
16
30
20
19
23
28
31
26
30
16
18
4
2
28
25
2
9
1
22
27
29
5
13
15
10
15
19
5
20
31
26
5
8
13
14
9
18
29
0.19
0.16
0.2
0.04
0.24
0.28
0.79
0.26
0.37
0.26
0.86
0.41
0.41
0.18
0.34
0.6
0.77
0.23
0.05
0.21
0.52
0.15
0.15
0.3
0.12
0.29
0.41
0.41
0.11
0.18
0.22
0.16
0.16
0.43
0.55
0.21
0.69
0.91
0.91
0.48
20
16
22
0.37
1.4
0.65
Snow removal strategy –
Maximum daily snow fall in
last 40 years
data wystąpienia
okres zimowy
rok
miesiąc
dzień
maksymalny dobowy opad
śniegu [cm]
1971/1972
1972
1
18
7
1972/1973
1973
2
25
8
1973/1974
1974
1
11
10
1974/1975
1974
12
31
5
1975/1976
1976
1
4
8
1976/1977
1977
2
15
11
1977/1978
1978
1
30
12
1978/1979
1979
1
30
25
1979/1980
1980
1
26
8
1980/1981
1981
1
15
6
1981
1
25
6
1981/1982
1981
12
26
10
1982/1983
1983
2
12
15
1983/1984
1984
1
25
10
1984/1985
1985
2
9
8
1985/1986
1986
1
26
24
1986/1987
1986
12
22
6
1987
1
12
6
1987/1988
1988
1
26
8
1988/1989
1988
12
9
4
1988
12
14
4
1989/1990
1989
11
22
7
1990/1991
1991
2
13
10
1991/1992
1991
12
25
7
1992/1993
1993
3
28
12
1993/1994
1993
11
12
5
1994/1995
1995
1
11
7
1995/1996
1996
2
20
10
1996/1997
1997
2
18
6
1997/1998
1998
2
3
8
1998
12
8
5
1999
2
16
5
1999
2
17
5
1998/1999
1999
2
24
5
1999/2000
1999
11
18
13
2000/2001
2001
3
24
6
2001/2002
2001
12
23
8
2002/2003
2003
2
7
13
2004
2
10
8
2003/2004
2004
2
29
8
2004/2005
2005
2
17
15
2005/2006
2005
12
30
16
2006/2007
2007
1
24
17
2008
1
6
4
2007/2008
2008
3
26
4
2008/2009
2009
3
24
14
2009/2010
2010
3
14
17
2010/2011
2010
11
29
27
corresponding load [kN/m2]
fresh snow
0.07
0.08
0.1
0.05
0.08
0.11
0.12
0.25
0.08
0.06
0.06
0.1
0.15
0.1
0.08
0.24
0.06
0.06
0.08
0.04
0.04
0.07
0.1
0.07
0.12
0.05
0.07
0.1
0.06
0.08
0.05
0.05
0.05
0.05
0.13
0.06
0.08
0.13
0.08
0.08
0.15
0.16
0.17
0.04
0.04
0.14
0.17
0.27
wet snow
0.28
0.32
0.4
0.2
0.32
0.44
0.48
1
0.32
0.24
0.24
0.4
0.6
0.4
0.32
0.96
0.24
0.24
0.32
0.16
0.16
0.28
0.4
0.28
0.48
0.2
0.28
0.4
0.24
0.32
0.2
0.2
0.2
0.2
0.52
0.24
0.32
0.52
0.32
0.32
0.6
0.64
0.68
0.16
0.16
0.56
0.68
1.08
Snow removal – general remarks
Snow removal – general remarks
Uneven snow distributions must be avoided
/ extremely unbalanced snow
accumulations can be critical.
-> Start snow removal at the area with most
snow accumulation within the selected area.
-> Do not accumulate snow in one location.
-> Work parallel at all axis
Snow removal method – Inner retractable roof
Removal of snow at the retractable roof would have been required once within the last 40
years. As per this strategy it would have been recommended in five years in order to stay
within the safe side. In order to maintain the full usability even for lots of snow in further 5
of the last 40 years a snow removal would have been necessary.
Option 1 – manual movement to
glass roof. Transport to inner edge of
glass roof with conveyor belt.
Option 2 – manual movement to
glass roof. Opening in glass roof.
Snow removal method – Inner retractable roof
The recommended option considers an opening of one glass pane per glass roof frame:
Following the inclination of the retractable roof the snow can be moved to the lower edge at the
glass roof (use of brushes, tear shovels or shovels), where it can be directly fall down to the pitch.
It is recommended to conclude with the Glass roof manufacturer the design of a small light wagon
with vacuum cups in and a lifting device for removal of the glass panes. In order to prevent men
falling it is recommended to design a grate with wide mesh to be put in the opening.
Snow removal method – Outer roof area 3 & 4
Removal of snow at areas 3 and 4 within the last 40 years would have been not required in
order to maintain the structural integrity, but would have been recommended once.
Two possible Options are shown:
Option 1 – manual removal
with shovels and pulltransporters.
Option 2 – Preparation of
drop down openings (like
man holes) at the deep point
close to the rockers.
Installation of snow slides
along the valley. Shovelling
snow onto the slides.
Special Equipment Slides
Special Equipment - Slides
Demonstration
of snow sliding
on a PVC
Membrane
Special Equipment - Slides
Shown just as examples –
open pipes recommended as
used in ski resorts
Special Equipment
- Special snow removal equipment in
order to avoid damages
- Test which equipment works well
and effective without damaging the
structure. (brushes, shovels, pull
slides, ...)
.... other
Safety Equipment, H&S Plan, Fixations
- Health and safety plan
- trained workmanship
- provisions for fixation of safety lines
Comparison of the two basic options roof closed/folded for winter
Roof closed in winter
Roof in garage in winter
Snow / Ice
removal
Possibility to Remove snow
from retractable roof in case
of high snow loads in order to
maintain the usability. No use
in case of extreme snow
MUST Remove snow /ice from
garage roof frequently, to
avoid avalanches / Ice fall on
the pitch. Snow removal on
pitch.
smoke exhaust
Confirmation by authorities
w.r.t fire/smoke restrictions
required. Smoke study on
hand.
No restrictions
Boundary conditions for movement of membrane
Criteria
Boundary condition
Temperature
> 5°C (>0°C is required, but for increase of lifetime >5°recommended)
Wind
< 10m/s
Rain, Humudity
No rain in next 30 minutes,
For folding: Membrane completely dry