Licciardello L.

Marchi Maurizio I.

Metelli Giovanni

Plizzari G. A.

Reggia A.

English

Archivio istituzionale della ricerca - Università di Brescia

Lucia Licciardellol.licciardello@unibs.itDesign, defects and durabilityReally cool concrete printingCyclic Response of a 3D Printed Concrete Shear Wall Made with Concrete ExtrusionLucia Licciardello1, Adriano Reggia1, Maurizio I. Marchi2, Giovanni Metelli1 and  Giovanni A. Plizzari11University of Brescia, Italy2Global R&D, Heidelberg Cement AG, GermanyEXPERIMENTAL CAMPAIGNIn order to assess the structural performance of the unreinforced 3DPC wall madewith concrete extrusion, an in-plane quasi-static cyclic test was performed. Thedesigned wall has a height of 3 m, a length of 3 m and a thickness of 55 cm. However,according to the maximum dimensions allowed by the available test setup and bytransport operation, the wall dimensions were reduced by a scale factor of 0.70.Therefore, the specimen was 2.10 m high, 2.10 m long and 38 cm thick. To simulatethe load of a two-storey building, a vertical load of 200 kN was applied by means oftwo hydraulic jacks. The horizontal load was applied with an electro-mechanic jack..The test set-up is shown in Figure 5.INTRODUCTIONWithin this study, the attention is focused on the extrusion process. The propercontrol of the material properties and of the printing process is essential in view ofthe printing of low-rise building. The design of a 3D printed concrete wall to beapplied in modular constructions of low rising building in seismic prone areas isdescribed. The aim is to identify the main thermal, geometrical, mechanicalparameters and investigate its structural performance. A critical discussion of theexperimental results is presented. Figure 1 shows a two-storey 3D printed concretebuilding prototype taken as an example.TEST SPECIMENThe investigation of the thermal performance of the wall was the starting point.The building was located in the north of Italy and it was designed to comply withthe current Italian legislation that set a maximum value for the thermaltransmittance U = 0.26 W/m2K. The configuration with inclined diaphragms waschosen as consequence of a parametric study, as it resulted to be the mostaffecting parameter. An inclination of 37°was adopted to guarantee an integernumber of internal diaphragms if a 3 m long shear wall is considered. The externalinsulation layer was added to avoid the problem of thermal bridges at intersectionpoints (e.g. between floor and wall).U = 0.19 W/ m2KRESULTSOnce the maximum tension strength was reached, the wall showed a brittle failurewith a horizontal flexural crack running at the interface of two filament layers. Firstcracking occurred during the push phase (point A+) at a load of 192.6 kN and a drift of0.8‰. On the reversal of loading, cracking appeared during the pull phase (point A-) ata load of -192.9 kN and a drift of 1‰. A critical crack, then, developed along the entirecross section (points B+ and B-) at a load of -217.5 kN and a drift of -1.6‰. After thecracking, a rocking mechanism followed (points C+ and C- in Figure 6).CONCLUSIONSThe structural response of a 3DPC wall under quasi-static horizontal cyclic loadingand constant vertical loading is characterized by high initial stiffness and highresistance to horizontal loads. Flexural failure occurred for very limited drift values(1.6‰) when the tensile strength of the material was reached. The wall showed abrittle failure with a horizontal crack occurred at the interface between the layersthus pointing out the weakness of printed structures to interlayer delamination.After cracking, a stable rocking mechanism followed. Eventually, it has to be notedthat the friction resistance of the critical section (after failure) was sufficient toguarantee rocking mechanism and prevent the wall sliding.The designed wall is characterized by an internal part with inclined diaphragmsthat has a structural function (in blue in Figure 3), meaning it is the part thatwithstand the vertical and horizontal load and an external concrete layer with justa thermal and aesthetic function (in orange in Figure 3).Figure 1. Two storey 3D printed concrete building prototype.Figure 2. Finite element analysis using the software therm: thermal flux..Figure 3. Unreinforced 3DPC wall: plan view.Figure 4. Unreinforced 3DPC wall: printing process.Figure 5. Test setup.Figure 6. Strain field from DIC: (a) first cracking at 0.8‰ drift; (b) critical cracking (peak load) at1‰ drift; (c) cracking associated to rocking mechanism up to 5.0‰ drift.-5 -3 -1 1 3 5-250-200-150-100-50050100150200250-250-200-150-100-50050100150200250-10 -8 -6 -4 -2 0 2 4 6 8 10Drift [‰]Load [kN]Load [kN]Displacement [mm]A+C+B+A-C-B-202.5 kN98.3 kN112.9 kN217.5 kN

Cyclic Response of a 3D Printed Concrete Shear Wall Made with Concrete Extrusion

https://iris.unibs.it/bitstream/11379/577165/1/DigitalConcrete_Poster_Licciardello.pdf

Cyclic Response of a 3D Printed Concrete Shear Wall Made with Concrete Extrusion

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Archivio istituzionale della ricerca - Università di Brescia