General Aspects for the construction of parapets or balustrades.
(n.b. Referring to Italian Legislation)
Terrace or staircase parapets, being a key guard for the protection against falling into the void of people or things are constructively bound to the respect of dedicated rules, this article is published with a view to clarifying the basic aspects of design and construction of parapets.
With reference to D.M. D.L. and D.P.R. the main constraints are:
- Height: The railing must be at least 1 meter high from floor level - workplace safety (D.P. 27-4-1955 No. 547) - overcoming architectural barriers (D.M. 14-6-1989 No. 236).
- Bosses on the inside: they must not have in the interior protrusions located at a height from the floor so as to favor the foot support and overtaking by the children.
- Maximum void size: must be fixed in such a way as to prevent the passage of objects; they must not let a sphere of 10 cm in diameter pass - overcoming architectural barriers (D.M. 14-6-1989 No. 236).
- Horizontal thrust resistance: the parapets must be able to withstand a horizontal thrust according to D.M. 14.01.08 applied to the height of the upper edge
From point a. it is evident that most of the parapets built from the 1960s until recently have not been conformed to the fact that the parapet is hardly 100cm high from the treadmill (it is not unusual to stand in front of 80-90cm high parapets). you should consider the height meter starting from the first horizontal that is usually placed 3-5cm from the floor bringing the total height of the parapet to at least 105cm from the floor of the floor.
By examining points b. and c. it is obvious that it is hardly correct (in terms of law) to make parapets with horizontal elements as they support the foot and favor the overtaking by children, these artifacts hardly have lights below 10 cm, an important feature in the construction of horizontal parapets the predisposition of an anti-scale system, making it inaccessible from the inside the first 75 cm in height of the parapet with appropriate mesh or glass protection systems, an interesting article on the subject and published by the upi ringhiere e parapetti.pdf
More complicated becomes respect for what D.M. 14/01/2008, which, although providing for home-made balustrades located in unusual and non-crowded areas (category a), a horizontal bearing resistance to the handrail floor at least 1kn / ml (100kg / ml) is the opinion commonly discussed widely through appropriate information seminars to consider Ballatoi Terrazzi and Scale as "Areas subject to crowding", so the load of vertex to be considered at design stage will be 2kN / ml.
3 BUILDING ACTIONS
3.1 INDUSTRIAL CIVIL WORKS
3.1.4 VARIABLE LOADS
Variable loads include loads related to the intended use of the work; the models of such actions may consist of:
- uniformly distributed vertical loads qk [kN / m2];
- vertical loads concentrated Qk [kN];
- Horizontal horizontal loads Hk [kN / m];
The nominal and / or characteristic values qk, Qk and Hk are reported in Table 3.1.II. These values include ordinary dynamic effects, provided there is no risk of resonance of the structures. Vertical concentric loads Qk are subject to separate local checks and do not overlap the corresponding vertical loads allocated; they must be applied on appropriate footprints for use and shape of the screen; in the absence of precise indications it may be considered a form of square footprint equal to 50 x 50 mm, except for remittances and car parks for which carriages apply on two 200 x 200 mm imprints, axially spaced by 1.80 mI values reported in Table 3.1.II refer to current use conditions of the respective categories. Other regulations may impose higher values, depending on specific requirements.
In the presence of atypical loads (such as machinery, tanks, internal deposits, plants, etc.) the intensity must be assessed on a case-by-case basis, depending on the foreseeable maximum: these values should be explicitly stated in the project documentation and static testing.
188.8.131.52 Horizontal variable loads
The horizontal (linear) loads indicated in Table 3.1.II must be used for local checks and do not add up to the loads used in building inspections as a whole.
Horizontal loads Hk shall be applied to walls at a height of 1.20 m from their respective floor planes and railings or sliding to the upper edge.
In this respect, it should be specified that such local verifications relate, in relation to the conditions of use, to the two-dimensional vertical elements such as scaffolding, walls, external blinds, however, realized, excluding movable dividers (which, however, must ensure sufficient stability in operation).
Prescription satisfaction can also be documented experimentally, and in any case by taking into account the constraints the artifact has and all the resources that the constructive type allows.
Table 3.1.II - Values of the workloads for the different categories of buildings (sourceD.M. 14/01/2008)
Environments susceptible to crowding
Libraries, archives, warehouses and environments for industrial use.
Cat. E1 Libraries, archives, warehouses, warehouses, manufacturing laboratories
Garage and Parking
Shells and enclosures
* It does not cover the horizontal actions possibly carried out by stored materials
Below we list the interlaces that can be used for certain sections of commonly used platforms for the construction of parapets (for continuous sections) using as a reference a 110cm high anchored anchoring parapet (without plates or mechanical anchors) with a 2kN lateral thrust, Obviously the data below is purely indicative because it does not take into account the singularities of each realization, the parapet verification can be carried out by professionally qualified personnel also in experimental as provided by the aforementioned DM
|Using the Elastic Resistance Module as a Calculation Criterion Wfel||Using the plastic resistance module as a calculation criterion S.L.U. Wfpl|
|Pillar section||Materials||Wfel||Permissible wheelbase||Wfpl||Permissible wheelbase (S.L.U.)|
It is obvious that if you are at your home at a height of at least 100cm, with pillars of 25x25mm section located at a distance of about 100-150cm as is commonly the case, you may be afraid that you will not have a product suitable for the purpose has been built, or at least does not respond in any way to the rules in question.
It is also noted that it is common opinion, widely discussed in a technical context through conventions, consider balconies and stairs as areas subject to crowding, therefore the parcel load for the parapets will be 2kn (200kg / ml).
This is just an indicative table that does not take into account factors that may be critical to the strength of your parapet, as you believe your railing does not conform to the standards, we recommend that you contact your trusted technician, Engineer, Architect, or Expert to evaluate the artifacts and, if appropriate, to identify the actions for the whole set!
According to the reference provisions, glazing structures must be verified with the static loads prescribed by the new D.M. 14/1/2008 "Technical Standards for Buildings" G.U. N ° 29 of 4/2/08 and subsequent updates and subject to the mandatory impact safety requirement as required by UNI 7697: 2007 ("safety criteria in glass applications") (L.206 6/9 / '05 ).
Compliance with UNI 7697 is an obligation since Law No. 206/2005 sets the norm 7697: 2007 as a rule.
This standard has about the features, the glass realizations.
With reference to the glass parapets, the requirements of UNI 7697: 2007 in point 8.2.4 - prospectus 1 are: Glass applications Applications and / or stresses Risks Minimum performance class 8.2.4 Glass plates of balustrades, parapets, internal partitions, bulkheads, divisions, etc.
Shock due to the impact of persons falling in vacuum 1 B 1 according to UNI EN 12600
It is also necessary that the parapet analysis be carried out in accordance with D.M.I. of 14.01.2008 and of the Circular of the Ministry of Infrastructure and Transport N ° 617 of 02.02.2009, PUBLISHED ON THE OFFICIAL JOURNAL ° 47 of 26/02/2009 suppl. Ordinary No. 27; and that the choice of glass type according to the particular application is made, and if it defines the thickness to bear loads and overloads, using the UNI 7143 computation method, it is also necessary to apply UNI EN 12600 "Test of pendulum - Impact test method and classification for flat glass "legislation classifies flat glass for building in three categories, based on impact performance and breaking mode.
The test used is the so-called "pendulum test" in which flat glass samples for building use are affected by a special semirigid body that simulates the accidental impact of a human body on the glass.
The pendulum consists of two special tires, whose characteristics are defined in a specific regulation and weighs 50 ± 0.1 kg.
The observed breaking mode, together with the height from which the pendulum was launched, are the parameters that allow to classify the various types of glass by means of the pendulum test it is necessary to test all the parapet system and not just the glazed slab, so in order to classify the conforming system 1B1, it is necessary to test on a sample that represents reality in the whole, glass, supports, planks, etc .. .