| The wood-based structural insulated panels are a kind of high-strength composite board combining insulating and structural function.It enjoys the advantages of high-quality,speed of installation,thermal efficiency and energy saving.In this study,OSB and structural plywood were used as the facing material,polyurethane insulation board as the core material,and one-component polyurethane structural adhesive as adhesive.SIPs with various structures were prepared and the influence on the mechanical properties of SIPs brought by test conditions and structural components was then discussed.Finally,the ABAQUS finite element software was used to simulate and analyze mechanical properties of SIPs,and the accuracy of the model was analyzed and verified.The main research contents and experimental results are shown as follows:(1)The minimum density of polyurethane insulation boards,structural adhesive and the optimum amount of adhesive were selected to be 40 kg/m3,one-component polyurethane structural adhesive and 180 g/m2(single face).The cold pressure for preparing SIPs was determined based on using the maximum pressure within the elastic limit range of the stress-strain curve.When the density of polyurethane insulation boards was 40 kg/m3,the optimum cold pressure was 160 k Pa.(2)The ultimate load decreased with the increase of span-height ratio for the in-plane and out-of-plane bending test.In the in-plane bending test,when the span-height ratio were 6,11,and 15,the ultimate load value were 40.05 k N,30.05 k N,and 28.24 k N respectively.In the out-of-plane bending test,when the span-height ratio were 7.5,13,16 and 18,the ultimate load values were 2.89 k N,2.12 k N,1.87 k N and 1.84 k N respectively.(3)The in-plane bending strength,transverse load capacity and axial load capacity of specimens increased with the increase of the loading rate.In the in-plane bending test,the ultimate load of the loading rate for 2.00 mm/min was 8.00% larger than the loading rate of 0.50 mm/min.In the transverse load test,the average ultimate load value with loading rate of 10.00 k N/min was 11.02% larger than the loading rate of 2.50 k N/min.In the axial load test,the average ultimate load value of specimens in 1-2 min destruction was 33.80% larger than the ultimate load value of 8-15 min destruction.(4)SIPs walls were tested using the two standards with ASTM E72 and ISO 22452 respectively and the ultimate load value was different.Under the standard test of ASTM E72 and ISO 22452,the load values of transverse load test were 17.12 k N and 16.56 k N,the load values of axial load test were 196.85 k N and 189.69 k N and the load value of racking resistance test were 29.42 k N and 31.11 k N.Because the creep effects in different tests lead to different test results,the ultimate load value under one continuously loading was larger than the ultimate load value obtained under gradually loading.(5)For the in-plane bending capacity,transverse load capacity,axial load capacity and racking resistance performance,the ultimate load value of SIPs with structural plywood were 58.86 k N,17.74 k N,224.38 k N,and 28.04 k N respectively,while the ultimate load value of SIPs with OSB were 30.64 k N,5.87 k N,196.85 k N and 27.74 k N respectively.The mechanical strength of SIPs sheathing with structural plywood facing was higher than that with OSB,which indicated that the higher the facings strength,the higher the mechanical properties of SIPs.(6)The mechanical properties of SIPs increased with the thickness of the core.The ultimate load value of the in-plane bending test were 29.96 k N,30.64 k N and 41.67 k N respectively for thethe core thickness of 90 mm,110 mm and 150 mm.The ultimate load value of the transverse load test were 14.89 k N,15.87 k N and 17.30 k N respectively for the the core thickness of 90 mm,110 mm and 150 mm.The ultimate load value of the axial load test were 169.11 k N,196.85 k N,230.09 k N respectively for the the core thickness of 90 mm,110 mm and 150 mm.The ultimate load value of the racking resistance test were 27.71 k N,29.42 k N,33.39 k N respectively for the core thickness of 90 mm,110 mm and 150 mm.With the increase of thickness,the transverse load increased slowly,while the axial load increases rapidly.For the transverse load test,the load value of SIPs with the core thickness of 150 mm was 16.19 % larger than the thickness of 90 mm.For the axial load test,the load value of SIPs with the core thickness of 150 mm was 36.06 % larger than the thickness of 90 mm.For the racking resistance test,the load value of SIPs with the core thickness of 150 mm was 20.50 % larger than the thickness of 90 mm.(7)The ultimate load value of the racking resistance performance were 36.63 k N,41.58 k N,41.15 k N respectively for the SIPs shear walls of 610 mm by 2440 mm modules,1220 mm by 2440 mm modules and 1220 mm by 1220 mm modules.The failure modes of the different module combinations were different and the squeeze misalignment occurred at the module gap.(8)The failure modes varied when it came to different span-depth ratio.For the out-of-plane bending test,the core shear failure occurs when the span-depth ratio was less than 18,while the facing material and core material were separated at glue line when the span-depth ratio was larger than 18.The in-plane flexural test failure mainly occurred at the connection of the SIP component,behaving with the nail connection disability and the facing panel collapse.The failure type and location of specimens with different structural composition were basically similar.In the ransverse load test core layer shear failure mainly occurred at the edge of the specimen.In the axial load test the failures were the core fracture and the separation of core and facing material.For the racking resistance test the SIPs and wall stud were mainly pulled up,except the bottom beam.(9)ABAQUS finite element software was feasible for simulating SIPs components.In-plane bending test and axial load test were modeled and analyzed.The experimental and simulated errors of the two kinds of tests were 8.35 % and 10.41 % respectively. |
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