The present invention concerns a modular car park.

In particular, the present invention concerns a modular car park with one or more raised levels.

It is known that, starting from 1990, we witnessed the emergence and the gradual affirmation on the market of various modular parking systems with one and subsequently more raised levels, designed to be installed on existing asphalt surfaces, without the need for foundations of traditional type.

Columns of this type of prefabricated modular structures are mounted on steel bases, which are simply resting on the flooring and which distribute the concentrated loads of the columns over a larger area. Such bases, generally consisting of steel plates and therefore identified hereinafter as plates, receive the concentrated loads of the columns and transmit pressures to the underlying yard which, for design purposes, must be checked from time to time applying the principles of geotechnics (and the reference standards) compatible with the bearing capacity of the soil of the yard in question. For convenience of reference, in the rest of the present specification, such type of structure will be defined as “without foundations”.

Multilevel car parks with standard dimensions of the drive aisle and of the parking space can be more or less comfortable to use depending on the number and position of the columns that may be present at the side of the drive aisle, such columns interfering with the manoeuvres to enter/exit the parking space.

Car parks without foundations were born in the 90s, arranged on a 5.0 x 5.0 m structural grid, as shown by way of example in Figure 1 . A 5.0 x 5.0 m module can be used both as a drive aisle (a 5.0 m long portion of a 5.0 m wide drive aisle) and as a parking space (two parking spaces measuring 5.0 x 2.5 m). With such structural mesh, each column receives the loads, both permanent and accidental, collected by 25 m ² of floor slab for the internal columns 1 , 12.5 m ² for the perimeter columns, 6.25 m ² for the corner columns 3. Such grid makes it difficult for the driver to park, due to the large number of columns.

Another issue with such traditional parking system without foundations consists in the high pressures transmitted by the plates themselves to the road surface. Such plates, in fact, as shown in Figure 2, wherein a plate is indicated by the reference number 4 and shown under a column 5, must have a maximum size of 60-70 cm per side (i.e. in diameter, if they are circular), since, if made larger, they would pose the double issue of not being sufficiently rigid and of hindering circulation of vehicles and pedestrians.

Such dimensions of the plates 4 cause the pressure bulb to be contained in the first metre of soil. This first metre of soil must have a high mechanical strength: if it is a granular soil, the average value of the friction angle must get values of about 40 degrees.

It is reasonable to be able to get such values in the first metre of soil below the yard, as the first 10-15 cm consist of a bituminous conglomerate, the following 30-40 cm consist of a compacted mix that acts as a foundation for the flooring, while between the depth of 0.5 m and the depth of 1.0 m there is a natural soil with acceptable mechanical properties or, if this is poor, during the yard construction it will have been replaced with a covering layer, called "capping layer", obtained with backfill materials well constipated.

However, often the geotechnical investigation may find mechanical characteristics poorer than those necessary to allow the use of plates of acceptable dimensions, which makes it impossible to realise the car park using the system without foundations.

This leads to two major interlinked issues concerning car parks without foundations which make use of steel plates placed directly on the flooring, which, summarising, are:

- manoeuvring difficulties by users;

- cases wherein the system cannot be used due to insufficient strength/stiffness of the soil.

Referring to Figure 3, it is also known that traditional multi-storey car parks often use a structural mesh called "clear span", with columns 5 positioned only at the end of the parking spaces 6. Such mesh is obviously to be preferred from the point of view of the comfort of use and in fact is rapidly supplanting other types that provides for columns near the drive aisle.

The transition to the "clear-span" meshes, for a parking system without foundations, is not immediate: even using a mesh with columns spaced apart by only 2.5 m, as in the example of Figure 3, the load on each column 5, and therefore on the underlying plate, increases by 50% compared to the “standard” system without foundations, which also makes use of columns along the drive aisle.

Therefore, it is not possible to realise a car park without foundations with a “clear span” mash making use of the discharging system to the ground which provides for bases in the form of square or circular steel plates, such as those used for the 5.0 x 5.0 m structural mesh.

The solution according to the present invention fits in this context, aiming to provide a discharging system to the ground capable of allowing the realisation of a car park without foundations with a "clear span" mesh, by making bases able to distribute the loads received by the structure in elevation over areas with a much larger footprint than the systems according to the prior art and meanwhile without hindering circulation of vehicles and pedestrians.

These and other results are obtained according to the present invention by proposing a new type of support plate for the system without foundations, which is inspired by some simple considerations: it is admissible to create portions of a parking surface with slopes of the order of 10% in circumscribed zones, as for example in case of parking spaces created on a slight slope, i.e. with at least the most distant portion from the drive aisle being on a slight slope, i.e. parking spaces with a slight cross slope, or even in case of drive aisles in the middle of which an upward portion and a downward portion are placed in succession to form a speed bump.

The aim of the present invention is therefore to provide a modular car park, which allows to overcome the limits of the modular car parks according to the known technology and to obtain the technical results previously described.

A further aim of the invention is that said modular car park can be realised with substantially low costs, both in terms of production costs and in terms of management costs.

Last but not the least aim of the invention is to propose a modular car park that is simple, safe and reliable.

Therefore, the specific object of the present invention is a modular car park comprising a plurality of aligned columns, a plurality of parking spaces being on at least one side of said structural mesh, such parking spaces being arranged in a direction transverse to said structural mesh, side by side and having a rectangular shape, with one side in correspondence with said structural mesh, said modular car park further comprising a foundation system, comprising a ribbon-like base, adapted to be arranged under said plurality of columns, said base comprising an upper portion or beam and a lower portion or plate, said plate extending in a transverse direction to a greater extent than said beam, wherein at least one portion of the upper part of the cross section of said base is sloping with a height increasing from the sides towards the centre of the base itself, said sloping portion extending for a distance on each side of said structural mesh which is less than 1/2 of the length of the sides of each parking space adjacent to said side in correspondence with said structural mesh.

In particular, according to the invention, said sloping portion extends for a distance, on each side of said structural mesh, which is less than 1/3 of the length of the sides of each parking space adjacent to said side in correspondence with said structural mesh.

Preferably, according to the invention, said plate has a flat lower base.

In particular, according to the invention, the cross section of said plate is symmetrical to a longitudinal vertical plane.

Preferably, according to the present invention, said oblique sides form an angle at the base not greater than 7° (slope lower than 12%) and even more preferably they form an angle at the base not greater than 6° (slope lower than 10%).

Alternatively, according to the present invention, said base is made entirely of reinforced concrete, or said plate is made of reinforced concrete and said beam is made of steel, in both cases at least one portion of said plate can be sunk below the level of the parking surface, the sides of the upper part of said base, possibly covered with the same covering as the roadway, being at the same level as the parking surface; or said plate and said beam are made of steel and preferably said plate rests on the parking surface.

The effectiveness of the modular car park object of the present invention is evident, allowing the realisation of a car park without foundations even with a "clear span" mash, by making bases able to distribute the loads received by the structure in elevation over large footprint areas, without hindering circulation of vehicles and pedestrians.

The present invention will now be described, for illustrative but not limitative purposes, according to a preferred embodiment thereof, with particular reference to the figures of the attached drawings, wherein:

- Figure 1 shows a plan view of a car park without foundations on a 5.0 x 5.0 m structural grid,

. Figure 2 shows an elevation view of a detail of a prefabricated modular structure without foundations according to the prior art,

- Figure 3 shows a plan view of a car park without "clear span" foundations,

- Figure 4 shows a side view of a parking space with the front portion slightly sloped and of a car occupying it,

- Figure 5a shows a sectional side view of a detail of a modular prefabricated structure without foundations of the "clear span" type according to a first embodiment of the present invention,

- Figure 5b shows a sectional side view of the base of the modular prefabricated structure without foundations of Figure 5a,

- Figure 6a shows a sectional view of the base plate of the modular prefabricated structure of Figure 5a, - Figure 6b shows a representation of the distribution of the pressure applied by the ground on the plate of Figure 6a,

- Figure 6c shows a representation of the distribution of the moment induced by the ground pressure on the plate of Figure 6a,

- Figure 7a shows a sectional side view of a detail of a modular prefabricated structure without foundations of the "clear span" type according to a second embodiment of the present invention,

- Figure 7b shows a sectional side view of the base of the modular prefabricated structure without foundations of Figure 7a,

- Figure 8a shows a sectional side view of a detail of a modular prefabricated structure without foundations of the "clear span" type according to a third embodiment of the present invention, and

- Figure 8b shows a sectional side view of the base of the modular prefabricated structure without foundations of Figure 8a.

Referring in particular to Figure 4, it is evident that an inclination equal to 10% (approximately 6 degrees) of the first third of the length £ of a parking space results in a maximum slope of the car A not exceeding 2 degrees, which is perfectly compatible with the parking operations as well as the operations of entry, exit and circulation of pedestrians around the car. Similarly, a slight cross slope of the parking space is acceptable: if the slope of a sloping portion of the floor is approximately 6 degrees, the slope of a car having the two wheels of the same side on such sloping portion and the two wheels of the other side on the flat surface is much more modest, equal to about 2 degrees on the horizontal. Likewise, it is equally acceptable to provide a speed bump in the middle of an aisle, consisting of an upward portion and a downward portion.

With reference to Figures 5a and 5b, taking into consideration a central row of columns 5 in the planimetry of Figure 3, and assuming for it a ribbon-like base 10 with the smallest possible thickness, but at the same time sufficiently rigid to convert the point loads received in correspondence of the columns 1 1 under a pressure as uniform as possible on the underlying ground, according to a first embodiment of the present invention it is possible to imagine this base 10 carrying out the aforementioned distribution into two phases: a first distribution phase is carried out by the central beam 12, which receives point loads at the extrados from the columns 1 1 above it, and transmits a load distributed along its axis to the underlying plate 13 with tapered wings; while the second phase consists in the distribution of the loads received centrally by the tapered plate 13, towards its ends, in order to reach pressures as uniform as possible at the interface between the plate 13 and the ground.

Example 1

Wanting to give numerical values by way of example, consider the columns 5 of the central row of Figure 3, equidistant with a pitch of 2.5 m and their discharges equal to 25 ton: the distribution made by the central beam 12 will ensure that one linear metre of the surface of support of the beam 12 on the plate 13 will be subjected to a force per length unit equal to 10 ton/m (25 ton/2.5 m). Assuming an admissible ground pressure of 0.5 kg/cm ² (5000 kg/sqm), it will be required a width of the plate 13 at least equal to 2.0 m, in order to maintain the contact pressure between the lower face of the plate and the ground within the limits of such permissible value.

In Figure 5b is represented in section the central foundation beam 10 according to the present invention, which in Figure 6a appears limited to the tapered sole 12: a linear metre of sole receives a force of 10 ton/metre which must be balanced by a uniformly distributed pressure applied by the foundation soil equal to 0.5 kg/cm ² .

Referring to Figure 6b, by schematically representing a half of the tapered plate 13 as an embedded bracket 14, this will be subjected to a distributed load 15 of 100 kg/cm. Referring to Figure 6c, the diagram of the bending moment 16 in such bracket shows how increasing the resistant section of the plate 13 from the edge towards the centre well approximates the moment diagram.

In the example in object, the base 10 is therefore constituted by two distinct superimposed and connected elements: a beam 12 oriented in the main direction of the foundation beam is superimposed and connected to a plate 13 which, in orthogonal section, shows its faces facing up which are tapered from the centre towards the ends. Such base 10 rests on the existing parking flooring in correspondence with a row of columns 5 of the clear span system.

At its ends, the plate 13 reaches a thickness of a few millimetres (a thickness up to 8 mm it’s not an issue).

When used for parking, the tapered plate 13 constitutes a slight ramp, on which the front wheels of a parked car climb for a short distance. The ramp slope thus identified complies with the geometric rules that apply to the ground connection of the normal ramps of raised car parks. In particular, such slope cannot be higher than 10%.

The height of the central part of the plate 13, on which the beam 12 rests, will therefore be approximately equal to 1/20 of the total width of the base 10.

For the example just discussed, given the wide transverse extent of the plate 13 (total width equal to 2.0 m) and the involved reduced thicknesses (maximum height of the plate 13 in the middle of about 1/20 of the total width = 10 cm) the plate 13 must necessarily be made of steel.

The pressure on the ground that can be obtained using this base 10 in a modular clear span car park, equal to 0.5 kg/cm ² , is nearly an order of magnitude lower than the pressure applied by the normal plates of a car park without foundations, an example thereof has been described with reference to Figure 2. In fact, the plate of the modular car park with one or more raised levels according to the prior art shown in Figure 2 is normally loaded with pressures approximately equal to 12-14 ton while in use, with pressures between 3 and 4 kg/cm ² , therefore between 6 and 8 times higher than the pressure applied in the above exemplified case.

However, it should be noted that the realisation of the steel plate 13 shown with reference to Figures 5a, 5b and 6a could be particularly expensive, due to the quantity of material and its processing. Furthermore, a steel plate 13 could be not optimal in scenarios other than the one described, such as for example those illustrated below.

Example 2

Referring again to Figure 3, considering a "clear span" structure with two raised levels realised on a ground with an admissible operating load equal to 1 kg/cm ² , which is double that taken into consideration in the previous example 1 , and keeping unchanged the width of the base 10, as a consequence the loads on the base 10 are double, with the risk of generating an excessive deformability of the steel plate 13 in respect of the applied loads. Although checked for a load which is double that shown in the bracket diagram of Fig. 6b, the base 10 undergoes excessive deformations, thus failing to maintain a sufficiently uniform distribution of pressures at the interface with the ground. Such tensions are high in the areas close to the axis of the beam 12, and are reduced moving towards the edges of the plate 13.

From an engineering point of view, it is possible to compensate by increasing the height of the plate 13 in the centre of the beam 12, for example from 10 to 15 cm; however, such change is not possible, as it would not be compatible with the geometry of the ramp, whose slope at its connection cannot exceed 10%.

Example 3

At this point, it should be noted that the main interest in realising car parks without traditional foundations lies mainly in the following aspects:

- no interference with the underground utilities, whose precise location is often unknown and/or cannot be determined;

- saving the time required for realising the foundations in order to deliver the work more quickly;

- realisation of the structure in steps, keeping a portion of the existing street level car park always in use during realisation of the work, and providing for partial redeliveries of its portions, in order to ensure a minimum number of parking spaces during its construction;

- exploiting the bearing capacity of the most superficial layers of the soil, which are generally made of well-compacted chosen materials, with an excellent bearing capacity;

- avoiding the production of debris from excavation that are dangerous or simply burdensome to dispose of, if the soil below the yard is polluted;

- adapting to the possible presence of archaeological remains below the existing flooring.

A good part of these objectives, which lead to prefer, for a given site, a structure without foundations, are still achieved if the only manipulation of the soil necessary to install the structure consists in the turf removal of some portions of the yard, with the removal of minimum thicknesses of soil between 5 and 20cm.

In fact, also in order to avoid damages, the underground utilities are always installed at a minimum depth of 30 cm below the parking surface, so that, by removing soil thicknesses having a depth of up to 20 cm, no underground utilities are encountered. The removal of thin thicknesses of turfs, up to 10-20 cm of depth, can be carried out by means of road milling machines, machines capable of treating surfaces having a precise geometry and large dimensions in a very short time, if compared with the time normally required for carrying out the excavation of foundations (especially taking into account the precautions to be taken for the excavation using mechanical means, in the presence of potential unmapped underground utilities, often present in the street level car parks of city centres, hospitals, airports or railway stations).

Consequently, it is reasonable to introduce, depending on the strength of the soil and the loads involved (i.e. the number of levels of the structure), bases 20 such as the one shown in Figures 7a and 7b, sunk 10 cm below the level of the parking surface. The plate 23, once again 2.0 m wide, has a thickness of 10 cm at its edges and a maximum thickness of 20 cm in its centre. Given the greater thickness, such plate 23 can be made of reinforced concrete rather than steel, thus achieving an economic saving.

Similarly to the embodiment shown with reference to Figures 5a and 5b, also in this case the columns 1 1 do not discharge their weight directly on the plate 23, but on a beam 22 placed in correspondence with the centre of the plate 23.

Example 4

Still referring to Figures 7a and 7b, if the plate 23 has a width B of 3.6 m, assuming a sinking H of 15 cm, the height in the centre is equal to 18 + 15 = 33 cm. Such thicknesses make it possible to realise 20 bases with significant transverse stiffnesses even with the use of reinforced concrete instead of steel.

Example 5

Figures 8a and 8b show a further embodiment of the present invention, wherein the base 30 is made entirely of reinforced concrete and is, therefore, designed to be sunk by a value H below the level of the parking surface: it is shaped as a plate 33 with tapered wings, which in the central part having an increased thickness further shows a raised portion, which acts as a beam 32, with a section in the form of an isosceles trapezoid, tapered upwards, i.e. in the direction of the columns 11 .

For the proper distribution of the load of the columns 1 1 , the beam 32 is tapered upwards.

The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is to be understood that variations and/or modifications may be made by those skilled in the art without thereby departing from its scope of protection, as defined in the attached claims.