Analysis of the Shear Capacity of Ultrahigh Performance Concrete Beams Based on the Modified Compression Field Theory

An analysis model of the shear capacity of prestressed ultrahigh performance concrete (UHPC) beams under the combined action of bending and shearing was established in this paper based on the modified compression field theory and by considering the unique material constitutive relation of UHPC. Shear tests were performed using three prestressed UHPC-T beams with different shear-span ratios to verify the correctness of the model. The results showed that the shear-span ratio greatly influenced the shear capacity and failure modes of UHPC-T beams. Upon increasing the shear-span ratio, the failure modes of the three beams were inclined compression failure, shear compression failure, and diagonal tension failure, successively. When the shear-span ratio changed from 1.04 to 2.12, the shear bearing capacity decreased greatly; however, when the shear-span ratio changed from 2.12 to 3.19, the decrease of the shear bearing capacity was very small. In addition, the MCFT analysis model was used to analyze the experimental data, and the predicted results were in good agreement, which proved the applicability of the model. Finally, according to the existing shear test results of UHPC beams and based on the main influencing factors, a simplified formula for predicting the shear capacity of UHPC beams was obtained by fitting. Comparing the MCFT model with the results of other pieces of literature, this formula accurately predicted the shear capacity of UHPC beams. The MCFT model and the simplified formula presented in this paper provide a powerful tool for predicting the shear performance of UHPC-T beams, which will contribute to the design and analysis of UHPC-T beams.

Prediction of perforation velocity of hard missile impacts on reinforced concrete wall panels

This study reviews and compares the most commonly used models for computing the local effects of hard missile impacts. The accuracies of the models in predicting perforation velocity are evaluated using a dataset of 95 impact tests collected from the literature. It is found that the majority of the models are unable to accurately predict perforation velocity or have a limited application range because of their empirical nature. To address these limitations, a semi-analytical model based on the Modified Compression Field Theory and the principle of work and energy is proposed. Unlike most existing models, the proposed model is capable of considering the influence of in-plane and shear reinforcement. The performance of the proposed model is assessed against experimental results obtained from the compiled dataset as well as other existing models.

Developing tension field action of embedded steel plates-Stiffened rebars composite reinforcement within concrete deep beams

For reinforced concrete beams, the shear failure mode is confirmed to occur in disturbed regions rather than in the Bernoulli region where stresses can be computed from the flexure formula. Thus, the provision of such regions with shear deficiencies is of great importance. In this study, a tension field system is suggested to embrace the inevitable concrete compression field originating within disturbed regions. Nine rectangular reinforced concrete beams dominated by disturbed regions are tested to verify the proposed shear reinforcement approach of the tension field concept. In this approach, the thin steel plate is embedded within shear span to resist shear strength in two different modes: with and without enhancement of reinforcement as stiffeners. All specimens were tested for failure using a four-point load testing arrangement. Test results demonstrate the feasibility of using embedded mild thin steel plate with and without ribs of rebars as tension field action against initiated concrete compression field action to upgrade the section shear capacity. As depicted by experimental results, the provided tension field system can remarkably upgrade the post cracking, stiffness, and ultimate shear capacity of the considered concrete beams. The stringer panel model is considered to verify and confirm strength improvement. The numerical solution is considered to investigate the proposed composite reinforcement provided within concrete deep beams using the concrete damaged plasticity model. The numerical investigation succeeded to depict the generation of tension field action within the suggested embedded steel plates–stiffened rebars composite reinforcement.

Study and Survey on Image Compression Techniques

In the Modern World, image is the important source for new technologies. The image compression is one of the important techniques which play a vital role in many applications. This paper presents the study of various image compression techniques which are used in the different Image Processing Applications. The advancement in the computer vision increases the demand of high data transmission speed also there is a need of large storage space. So, the image compression field is a necessary one for such applications where high volume of data is required to store and transmit. This paper focuses on the area of image compression, advantages of image compression, types of image compression and its different types of techniques. In addition to that, one of the new lossless image compression techniques ABO is explained. In this paper, it gives the overview of the ABO Framework and the ABO mechanism.