STUDY ON HYSTERESIS BEHAVIOUR OF REINFORCED HYBRID FIBER REACTIVE POWDER CONCRETE BEAM-COLUMN SUB-ASSEMBLAGES

• Main Author: Muslim prayogo, Gigih
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62415
• Institution: Institut Teknologi Bandung

High performance of compressive strength and durability of RPC material has implications for poor ductility property of RPC itself, but this issue could be eliminated by adding several fibers at once, such as steel fibers and synthetic fibers like polyropylene which known as hybrid fiber reactive powder concrete (HFRPC). Investigation of the hysteretic behavior of the exterior beam-column joint (BCJ) structure made of HFRPC at the joint region through 3D-finite element (FE) modeling was carried out using commercial software LS-DYNA by using implicitstatic analysis solution. Concrete damage plastic model (CDPM) was chosen as the material model for the concrete material. The monotonic and cyclic uniaxial response of compression and tension of normal concrete, the confinement effect, the effect of strain penetration through the bond-slip reinforcement mechanism, and the hysteretic response of the exterior BCJ structure with normal concrete were validated against the experimental results. Pushover analysis was carried out to investigate strain penetration effect through bond-slip reinforcement mechanism, due to the bond-slip reinforcement formulation being limited to monotonic response only. The exterior BCJ structure to be validated consists of two models, namely BCJ with the normal concrete material without stirrup reinforcement at the joint (NCJT- 0) and BCJ with stirrups at the joint as required by ACI-318 (NC-JT-1). Pushover results of the exterior BCJ model with bond-slip reinforcement can increasing accuracy in terms of stiffness and maximum load prediction on the experimental results, but in general, pushover analysis fails to capture the experimental backbone curve. Hysteretic response of the numerical models NC-JT- 0 and NC-JT-1 shows a good agreement in terms of force at each loading cycle. The initial stiffness of the experimental results cannot be captured properly by the FE model, where the average error value for the initial stiffness of the NC-JT-0 and NC-JT-1 models when the drift reaches 0.75% are 40.3% and 46.1% respectively. Results of the cumulative energy dissipation of the FE model while drift load reach 2.5% have a fairly good response to the experimental results, but after reached those drift, the results of cumulative energy dissipation yields a larger error along with the drift increased. At the end of loading cycle, NC-JT-0 and NCJT- 1 models has 28.2% and 67.8% error value compared to experimental results. Uniaxial compressive and tensile response of HFRPC material were validated against experimental results. BCJ model with RPC material without stirrups at the joint region (RPC-JT-0) can increase the joint shear strength by ±25.6% compared to the NC-JT-0 model. Failure type of numerical models NC-JT-0 and RPC-JT-0 is in accordance with the experimental results, which is joint shear failure. Shear strength increasing of the RPC-JT-1 model against NC-JT-1 is ±4.0%, shear strength of the JT-1 model has limitation on beam flexural capacity, which yields beam failure phenomenon. Ductility property of RPC-JT-0 the model at ultimate and failure load condition was decreased by ±23.0% and ±26.0% against the NC-JT-0 model. There is no decreasing on ductility property of the RPC-JT-1 model against the NC-JT-1 model, where the ductility value tends to be the same, which is 8.5% and 1.3% greater under ultimate load and failure load respectively. The stiffness degradation of BCJ made of RPC and NC are having similar property, but the model with the joint made of RPC had a slightly higher initial stiffness compared to joint made of NC. A significant increasing of cumulative energy dissipation property at the end of the loading cycle due to uses of RPC material, only occurs in the BCJ model without joint hoops reinforcement. The strength prediction of structural components such as joint shear strength and beam flexural strength through several analytical methods was also carried out with intention of adding another verification method of numerical results.