Abstract. In the view of the project problem that concrete strength grade is lower than C15in reinforced concrete beam, we consider a composite technology strengthened with CFRP, and do some monotonic loading experiments on these beams with eight different methods, and discuss the beam force behavior including ultimate bearing capacity, failure model and crack propagation. This paper finds out that the composite reinforced scheme, which with ticking trough, planting steel displaces concrete and gluing and then pasting CFRP, has a remarkable improvement than pasting CFRP immediately, and that there is a high coherence workability in the old and new concrete, so we can give full play to their role as the CFRP high strength.
Based on the test by the split Hopkinson Pressure Bar (SHPB), in this papaer the research on the dynamic mechanical properties of concrete under high temperture has been conducted, the influence law of temperature and strain rate on the mechanical peoperties has been analyzed, and the dynamic stress-strain curves of concrete under high temperature have been obtained. Analysis indicate that the concrete strain rate hardening effect is coupled with the high temperature weakening effect. Therefore, on the basis of classical damage theoretical model, in accordance with the concrete high-temperature dynamic mechanical characteristics, a unified equation is established to describe the whole process of concrete dynamic stress-strain relationship under high temperature, which is well coincided with the test results.
SPHB tests of concrete under different temperatures and various loading conditions are completed, and high-temperature dynamical behavior of concrete is obtained. Dynamical mechanical behavior of concrete with high temperature is affected by not only the strain rate effect, but also the high temperature weakening effect, and the strain rate hardening effect is coupled with high temperature weakening effect, but the latter has greater influence. Concrete failure evolution is described on basis of the damage factor, the intercoupling strain rate hardening effect and temperature weakening effect are simply set as mutually independent factors, each parameter is respectively fitted with test data, finally, concrete constitutive equation under high-temperature dynamical conditions is established, and comparative analysis with test data are conducted, indicating good coincidence with test results.
This paper proposed a lane detection algorithm for urban environment. The algorithm was concerned on selecting an appropriate limited region of interest (ROI) by OTSU segmentation. Then candidates of lane markers were extracted by Canny, finally the lane boundaries were detected by Hough transform. The limited ROI helps to identification lane in an appropriate region. This process have the effect of enhancement in the speed of operation. The proposed algorithm was simulated in MATLAB. The test databases were shared by Fondazione Bruno Kessler (FBK). The experiments show that lane boundaries can be detected correctly although they are fade. Feature-based method is usually affected by intension of image. Several characteristics of roads need to be considered further for detection more precisely.
The cold-formed thin-walled tube has been widely applied in high seismic fortification intensity region and post-seismic reconstruction area because of light quality, high strength and small deformation. But the connection mode and mechanical properties of beam-column connections still need further study. According to the "strong column and weak beam" seismic design principle and the thinking of control the position of plastic hinge, adding haunch slabs at the end of beam to reduce the number of repeated welding and avoid brittle fracture. Through the low cyclic loading experiment, four beam-column connections with welded haunch under different axial compression ratios have been studied, and connection’s hysteretic performance, energy-dissipating capacity, bearing capacity, rigidity and failure mode have been discussed. The result shows that: 1) the ultimate bearing capacity of connection with welded haunch is much great, and the energy dissipation capacity is very well, which can make this connection to absorb and consume great energy in earthquake. This connection can meet the need of seismic design very well. 2) The connection with welded haunch experiences much cycling time, has long yield platform after yield, has great cumulative energy-dissipating capacity and well ductility. 3) the final destruction of connection with welded haunch is caused by the beam’s local buckling. And the yield surface is almost located at the outside of connections. 4) The axial compression ratios has great effect on the hysteretic performance, bearing capacity and stiffness degradation for the connection with welded haunch.
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