Uncertainty Bounding of CFRP Beams Towards Robust Control of Flexible Composite Structures

As composite materials are becoming increasingly applied in actively controlled flexible structures, the need for practical uncertainty bounding to capture the effect of normal manufacturing variations on their dynamic behavior is also increasing. Currently, there is a lack of quantification of manufacturing variation of composite materials cast in a robust control framework. This work presents a simple experimental study on a particular case of composite member. The modal parameters of a set of 12 unidirectional carbon fiber reinforce polymer beams are identified. A nominal finite element model is numerically fit to the average experimental natural frequencies and antiresonances. The model is augmented with real parametric uncertainties placed on the modal parameters. The bound on the uncertainties is found both deterministically, to capture all experimentally observed data, and stochastically using a predetermined confidence interval. The two uncertainty bounding approaches are compared through the resulting bound on the beam model frequency response. Also, simulations are conducted to compare possible time responses using the two uncertainty bounds. It is found that the utilized structure of parametric uncertainties is effective at capturing the experimentally observed behavior.

Elasto-kinematics design of an innovative composite material suspension system

In this paper, a lightweight suspension system for small urban personal transportation vehicle is presented. A CFRP (Carbon fiber reinforce polymer) beam spring has been used to efficiently integrate the functions of suspension control arm and anti-roll bar. Composites materials were chosen to tailor the required behavior of the beam spring and to reduce the weight. Furthermore, larger space for engine compartment has been provided thanks to the compact arrangement of beam suspension components. This suspension could be installed on electric/hybrid vehicles and conventional automobiles.

Comparison of Seismic Behaviour for a Single Unit Tunnel Form RC Building before and after Repaired

Repairing and strengthening the structures are gaining more attention from many researchers and structural engineers after the structures suffered damages from natural disasters. Tunnel form RC buildings which are not designed according to seismic code of practice are very vulnerable to ground motion when located to near field earthquake. This paper presents the method of repair and strengthening of 3-storey tunnel form building subjected to in-plane lateral cyclic loading. The building was strengthened using the combination method of steel angle, steel plate and Carbon Fiber Reinforce Polymer (CFRP) sheet. The results show that the lateral strength capacity is increase by 15.66%, ductility increase by 53.57% and equivalent viscous damping increase by 28.88% for the first cycle and 33.65% for the second cycle. However, the stiffness of the structure reduce by 56.6%. It can be concluded that this method can be adopted for the damage of tunnel form building system.

Calculation of Shear Capacity of Steel Reinforced Concrete Beams Strengthened with Near-Surface Mounted CFRP Rods

Some calculated methods of shear capacity of RC beams strengthened with NSM(near-surface mounted) CFRP(Carbon fiber reinforce polymer) rods are reviewed based on the experimental data on shear capacity of RC beams strengthened with NSM CFRP rods. Therefore, according to the destruction forms of steel reinforced concrete beam strengthened with NSM CFRP rods, the formula for calculating the shear capacity of the beam is given. The formula is expressed clearly, simple and easy to use.

Calculation of Flexural Capacity of Steel Reinforced Concrete Beams Strengthened with Near-Surface Mounted CFRP Rods

Based on earlier theoretical works on RC beams ,the mechanical properties of steel reinforced concrete beams strengthened with NSM (near-surface mounted) CFRP (Carbon fiber reinforce polymer) rods are further investigated theoretically including theirs failure mechanism and load ability. According to the stress patterns of steel reinforced concrete beams strengthened with NSM CFRP rods and different position between neutral axis and steel, the discriminant formula of the boundary destroys and the formula of cross-section flexural capacity calculation are put forward by using limit equilibrium theory.The formula is expressed clearly, simple and easy to use.The depth of compressive region is given in view of different failure types.

Cyclic Behavior of Concrete Confined by Active and Passive Jackets

Shape memory alloy (SMA) wire jackets for concrete are distinct from the conventional jackets of steel or FRP since they provide active confinement that can be easily archived due to the shape memory effect of SMAs. This study uses NiTiNb SMA wires of 1.0 mm diameter to confine concrete cylinder with the dimension of 300 mm × 150 mm (L × D). The NiTiNb SMAs have a relative wider temperature hysteresis than NiTi SMAs and, thus, are more applicable for severe temperature-variation environment which civil structures are exposed to. Steel jackets of passive confinement are also prepared to compare the cyclic behavior of active and passive confined concrete cylinders. For this purpose, monotonic and cyclic compressive loading tests are conducted to obtain axial and circumferential strain. The both of strains are used to estimate volumetric strains of concrete cylinders. Also, plastic strains from cyclic behavior are also estimated. For the NiTiNb SMA jacketed cylinders, the monotonic axial behavior differs from the envelope of cyclic behavior; this should be studied in future. The plastic strains of the active confined concrete show a similar trend to those of the passive confinement. The trend of plastic strain of this study does not match with that of CFRP (Carbon Fiber Reinforce Polymer) jackets. For the volumetric strain, the active jackets of the NiTiNb SMA wires provide more energy dissipation than the passive jacket of steel.