دانلود رایگان مقاله اثر بستری در محل هندسه پانل قالب های پی وی سی بر رفتار خمشی دیوار بتن مسلح

ABSTRACT

The use of stay-in-place (SIP) formwork has become an increasingly popular tool for concrete structures, providing advantages in construction scheduling and labor reduction. Previous research suggests that PVC provides an enhancement to reinforced concrete strength and ductility. The research herein outlines tests on reinforced concrete walls with a compressive strength of 25 MPa, utilizing two types of PVC panels: flat or hollow, in order to further understand the polymer's contribution to flexural resistance. Variables studied included concrete core thickness (152 mm, 178 mm, and 203 mm), reinforcing ratio (3–10 M bars or 3–15 M bars), and panel type (hollow or flat). The walls were tested in four point bending. Walls failed due to steel yielding followed by concrete crushing, PVC buckling, and/or PVC rupture depending on the reinforcement ratio and panel type. The hollow panel encased specimens also experienced slip of the panels on the tensile face. The PVC encasement enhanced the yield load, ultimate load, ductility, and toughness of the concrete walls. Concrete cores were taken from the tested PVC encased specimens and compressive strength was found to be the same as the control walls.

4. Conclusions

The following conclusions can be made from the experimental results: 1. All PVC encased specimens failed by steel yielding on the tension side and concrete crushing and PVC buckling on the compression side. Differences in failure mode were a result of the PVC panel tension rupturing (flat panel) or experiencing differential elongation (hollow panel). 2. PVC encasement improved the load capacity of the reinforced concrete walls. For flat panel encased walls, the average improvement at yield and ultimate loads was 21% and 27% respectively. Hollow panel encased walls recorded average yield and ultimate load improvements of 8% and 27% respectively. The effect of the PVC encasement lessened as the reinforcing ratio or wall thickness increased. Lightly reinforced, thin walls had the highest improvement. 3. A comparison was made between walls with the SIP PVC system and walls that were conventionally constructed and 25 mm (1″) thicker. The yield and peak loads were very similar in this comparison, suggesting the potential for using the SIP system as a means to reduce the wall thickness and achieve the same structural performance. 4. PVC encasement improved the ductility at ultimate load level and the toughness of the reinforced concrete walls by an average of 50% and 96%, respectively. 5. There was no statistically significant difference observed in the concrete strength of PVC encased walls and traditionally formed concrete.