Device that limits the extent of roof collapse due to local damage

专利摘要:
The invention relates to devices located between trusses (5) and (5 ') in the form of load-bearing elements (6) and (6'). In the event of a local collapse of the roof, the load-bearing elements (6) and (6 ') give a corresponding limitation on the size of the damage area as if pillars were placed in the position of the load-bearing elements' connection to the roof trusses.
公开号:SE1300115A1
申请号:SE1300115
申请日:2013-02-14
公开日:2014-08-15
发明作者:Jörgen Thor；Tomas Fagergren
申请人:Fagergren & Thor Inv Ab；
IPC主号:

专利说明:

not detected during the prescribed routine inspection and which suddenly fails with an increased load.
Collapse of a load-bearing structure due to local fire is also counted as accidental load. This case may include, for example, a locally limited fire in a food hall that results in a collapse of e.g. a pillar or part of a truss. When the fire has reached such a size that the load-bearing capacity of the structures is jeopardized and a local collapse is risked in connection with the fire, no mare, including personnel from the rescue service, can be in the vicinity of the fire due to the radiant heat caused by the fire.
The important thing in this context is then that the primary local damage caused by the fire does not propagate far outside the fire area or results in a so-called progressive race. Current design standards therefore contain requirements for sufficiently strong connections and requirements for cohesion between individual construction elements or a limitation of the permitted total collapse area due to local crime as a result of an accidental load. The greater the span and the greater the load, the greater the requirements for the required cohesive forces to limit the size of the damage as a result of an accidental load.
Regarding local collapse due to fire in current types of buildings, the National Board of Housing, Building and Planning has specified both the size of the fire and the requirement for a maximum permitted collapse area or damage area outside the fire area in EKS (Boverket's regulations and general advice on applying Eurocodes).
In this context, the National Board of Housing, Building and Planning has expressed an interpretation regarding how the claims area is to be calculated that deviates from current practice applied by the industry for more than 50 years. When assessing the size of the damage area that can be considered dangerous to humans, the above-mentioned cohesion between the various construction elements must not be taken into account. In practice, this means that when calculating the size of the damage area, it must be assumed that the entire structure damaged locally at some point falls "flat" to the ground between its vertically supporting supports. If, for example, a roof truss is damaged locally due to a fire in connection with a pillar or other storage, an area of damage corresponding to the entire distance from this storage to the second storage of the roof truss and in the perpendicular direction the entire 3 distance from the damaged truss to the roof trusses on either side of this lying unaffected. If the damage area calculated in this way extends somewhere outside the circle area which, according to EKS, is accepted as the damage area in the event of a local fire, the construction is not considered to meet current requirements. In principle, this means that trusses with span widths greater than 12 meters cannot be managed. In current types of premises, the spans are often larger.
One way to then meet the requirements according to EKS for, for example, a truss with a larger span in the types of buildings in question is to protect the truss from fire in a certain prescribed fire technical class. In this way, it is assumed that the time is delayed until a crime occurs due to the fire. There is then no requirement to assess the size of the damage area according to the above. However, protecting the most common type of roof post from this type of building, namely a steel truss, is very costly. The cost of fire protection is usually as high and in some cases even higher than the cost of the truss itself.
Another alternative is, of course, to shorten the spans through the pillars and thereby limit the area of damage in the event of a local crime. This then instead comes into conflict with the company's requirements for a limited number of disruptive pillars.
The present invention solves the problem of limiting the damage area in the event of a local crime due to a fire according to EKS, or due to another accidental load, without the need for a disturbing pillar and without the need for costly fire protection of the trusses.
The invention is described in more detail with reference to the accompanying drawings, of which Figure 1 shows a plan and a section of a typical hall building with specified assumed fire impact and acceptable damage area Figure 2 shows estimated damage area in case of fire according to the above interpretation Figure 3 shows how current damage area is limited within acceptable damage area through the device according to the present invention Figure 4 shows how load-bearing forces are activated via the device according to the invention Figure 5 shows how forces generated when needed are passed on to the foundation Figure 1 shows in plan and section a typical hall building.ex. a food hall with a roof structure built up of primary beams, secondary beams and profiled sheet metal. As typical spans, 12 meters have been chosen for the primary beams and 24 meters for the secondary beams with a center distance of 6 meters.
A dimensioning fire 1 according to EKS is placed in the fi guren located in the middle of a primary beam. The figure also shows according to EKS accepted damage area 2 as a result of the fire.
Figure 2 shows the current damage area 3 of the fire determined in the National Board of Housing, Building and Planning's opinion. This means that the fire-exposed primary beam 4 is assumed to collapse completely between its column supports and that the secondary beams 5 and 5 'are assumed to completely collapse between their supports on the primary beam and the respective supports in the facade. The current damage area is thus largely outside the accepted damage area. The roof construction is thus considered not to meet current fire requirements for the current type of building.
Figure 3 shows the size 3 of the damage area for the same fire 1 as before but with a device according to the present invention. The device connects the 24 meter long secondary trusses to each other via load-bearing elements 6 and 6 ', in the present case placed in a position corresponding to about half the span of the secondary trusses. The load-bearing elements have no static function in the normal load case. In the event of a breach of the primary beam 4 and the secondary beams 5 and 5 'in connection with the fire, on the other hand, a similar effect on the damage image and the damage area is achieved via the load-bearing elements 6 and 6' as if additional pillars had existed in the position of load-bearing elements truss 5 and 5 '. The trusses 8 and 8 'and 9 and 9', respectively, are adjacent trusses to the roof trusses locally affected by the fire.
Figure 4 shows how, in the event of a break due to the fire as above, a certain deformation occurs in the position of the load-bearing elements 6 and 6 'connection to the roof trusses 5 and 5'. Thereby, tensile forces 7 'and 7' are activated in the load-bearing elements, which tensile forces are transmitted and absorbed by adjacent pairs of secondary trusses 8 and 8 'and 9 and 9', respectively, according to Figure 4.
The size of the tensile forces 7 and 7 'and the dimensions required thereon on the load-bearing elements are i.a. a. a function of the load area and the load per unit area that in the event of a fire should have loaded an imaginary pillar in the position of the load-bearing elements' connection to the secondary roof trusses. Adjacent trusses 8, 8 'and 9, 9', respectively, to which the resulting forces are transmitted are dimensioned to be able to absorb the widespread roof load in the event of a fire, plus the loads applied via the load-bearing elements.
The load-bearing elements 6 and 6 'can be anchored to the top, bottom of the trusses or in a suitable position in between.
The load-bearing elements 6 and 6 'can be made of steel and then preferably in the form of steel wires with high strength. The elements can be long and continuous between fl era or all trusses alternatively consist of short parts with a length corresponding to the distance between two trusses. In this case, they can have devices at each of their ends, for example in the form of cabin hooks, which means that they can be quickly anchored between the roof trusses.
Figure 5 shows how, depending on the design and dimensioning of the roof and depending on the load reduction of horizontal forces normally occurring in the roof panel, the tensile forces 7 and 7 'activated by fire in the load-bearing elements can be lowered to the ground via special devices 10 and 10 '.

权利要求:
Claims (7)
[1]
Devices located between trusses (5) and (5 ') in the form of load-bearing elements (6) and (6'), characterized in that in the event of local collapse of the roof the load-bearing elements (6) and (6 ') give a corresponding limitation of the size of the damage area as if pillars were placed in the position of the load-bearing elements' connection to the trusses.
[2]
Device according to Claim 1, characterized in that the load-bearing elements (6) and (6 ') are made of steel structures.
[3]
Device according to Claim 2, characterized in that the load-bearing elements (6) and (6 ') are made of steel wires.
[4]
Device according to one of the preceding claims, characterized in that the load-bearing elements (6) and (6 ') are connected to the center of the respective span of the respective truss.
[5]
Device according to one of the preceding claims, characterized in that the load-bearing elements (6) and (6 ') extend between all adjacent trusses for which a limiting width limitation is required.
[6]
Device according to one of the preceding claims, characterized in that the load-bearing elements (6) and (6 ') are dimensioned to support a load corresponding to the load which would be loaded on pillars placed in the corresponding position as the load-bearing elements (6) and (6'). ) connection to the trusses (5) and (5 ').
[7]
Device according to one of the preceding claims, characterized in that the 9: 7 forces (7) and (7 ') activated in the load-bearing elements (6) and (6') are transmitted for receiving adjacent unaffected trusses (8). and (8 ') and (9) and (9'), respectively. Device according to one of the preceding claims, characterized in that the load-bearing elements (6) and (6 ') consist of a number of short parts with a length corresponding to the distance between the trusses. Device according to Claim 8, characterized in that at the end of each part the device is provided for rapid mounting to the roof trusses.

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同族专利:

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公开号 | 公开日

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SE539307C2|2017-06-27|

引用文献:

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公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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法律状态:
2021-09-28| NUG| Patent has lapsed|

优先权:

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申请号 | 申请日 | 专利标题

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SE1300115A|SE539307C2|2013-02-14|2013-02-14|Device that limits the extent of roof collapse due to local damage|SE1300115A| SE539307C2|2013-02-14|2013-02-14|Device that limits the extent of roof collapse due to local damage|