INTERVENTION OF BUILDING RENOVATION AT THE HEADQUARTERS OF CASSA DI RISPARMIO DI CENTO S.P.A. LOCATED IN VIA MATTEOTTI N.8/B IN THE MUNICIPALITY OF CENTO (FE)
CONTRACTOR: Cassa di Risparmio di Cento S.p.A.,Via Matteotti 8/b – Cento (FE)
SERVICES RENDERED: structural executive project, structural supervision and safety during design and execution phase.
AMOUNT OF WORKS: € 3.000.000
BEGINNING/END OF WORKS: 2009/2010
CONTRACTOR: DUCTUS S.r.l., via Negrelli 13/b – Bolzano, LA PIRAMIDE S.r.l., C.so Guercino 76 – Cento (FE) and B.A. di Bertolani Alessandro via del Lavoro 2 – Carbonara di Po (MN)
As part of the renovation of the Cassa di Risparmio di Cento headquarters, the structural intervention has provided for the replacement of about 370 m2 of reinforced concrete roofing with new metal reticular structures on which are located the so-called “velari”, i.e. large square mesh windows necessary for the natural lighting of the new entrance hall of the bank and of various internal offices.
The existing roof was made with structural elements in reinforced concrete consisting of beams of different sections (generally T-shaped with dimensions Htotx Btot x banima x hala = 80x 100x30x 16 cm) placed at an interaxis of about 2.75 me pillars generally square section 30×30 cm or rectangular.
The floors, 16 cm thick, were made of concrete in the blind parts and glass in the portions between the interaxis of the beams. The existing structures object of demolition were in their turn inserted in a context structure composed of elements belonging to two adjacent buildings, in particular the support beams of the glass blocks are in simple support on the beams of these buildings so as to transmit only vertical loads.
The level of knowledge of the existing structures was provided by structural and calculation drawings related to the area of intervention from which it was possible to obtain the necessary information to detect the main geometric characteristics and constraints of the elements to be demolished, as well as information related to the analysis of loads. The original structure project dates back to 1970.
The guiding criteria for the design of the new structural elements were as follows:
1. Respect for the existing structural design in terms of constraints and load bearing arrangements;
2. Use of significantly lighter structures in order to achieve a seismic improvement assessable with the reduction of seismic masses equal to 40% at the level of the roof.
The new structures follow the existing load warps therefore the veils 2-3-4 have orthogonal warps compared to the veil n.l. The constraint systems are similar to the existing ones therefore all the veils have the three prevented translations on one end and a free translation along the warp on the other end. The canopies are made with Monier type trusses, placed at a constant distance between centres equal to l.30m in the direction of the warping, and transversal elements having a stabilizing and architectural function to create a square mesh of 1.30x l.30m. On the planimetric mesh of the trusses are obtained the areas occupied by the glazing of the veils and the blind areas made of corrugated sheet metal floors and cast collaborating for a total thickness of 90mm. The blind parts constitute transversal stiffening and constraint for the upper beams of the trusses.
All trusses are composed of loose bolted elements. The spans involved are as follows:
1. Velario n.3: average light of the main trusses is about 12.20m; light of the transversal trusses is about 10.40m;
2. Velario n.1: average light main trusses equal to 11.SO m plus a cantilevered portion beyond the beam in e.a. equal to l.SOm about; light transverse trusses equal to 7.80m about. The structural scheme of the main truss is simply supported beam with an overhang at one end similar to the existing structure scheme.
3. Velario n.4: medium light trusses main equal to 11.SOm approximately; light trusses transverse equal to 2.60m approximately;
4. Velario n.2: average light main trusses equal to 8.20m about; light transverse trusses equal to 2.60m about.
The anchorages to the existing structures are realized through systems of chemical anchorage. The translations along the longitudinal axis of the main trusses are realized by means of asciate plates.
The structural analysis and the current checks on the profiles have been carried out using the Win-Strand 2009 calculation code produced by ENEXSYS S.r.l. Via Tizzano 46/2 Casalecchio di Reno (Bologna) and the post-processor dedicated to steel structures called Win AciVer. The calculation method used was the limit state method according to DM 14/01/2008.