Bearing Capacity of Concrete Filled Steel Tube Circular Arch under the Six-Point Uniformly Distributed Loading and Its Engineering Application

The influence of rise-span ratio on the bearing performance of concrete filled steel tube (CFST) circular arch was studied in this paper, three groups of CFST circular arch specimens with different rise-span ratios (0.154, 0.207, and 0.26) were selected, the six-point uniformly distributed loading was performed, and bearing performance experiments on CFST circular arch specimens with fixed ends were carried out. In this study, the ultimate bearing capacity and deformation failure characteristics of CFST circular arch specimens were obtained. The comparative analysis shows that the deformation evolution of CFST circular arch specimens has experienced compaction stage, elastic stage, elastic-plastic stage, and plastic stage. In the elastic-plastic and plastic deformation stages, the circular arch shows good ductility and bearing capacity. The bearing capacity of the circular arch is significantly affected by the rise-span ratio. Compared with circular arch specimens with a rise-span ratio of 0.154, the yield load of specimens with a rise-span ratio of 0.207 and 0.26 is increased by 50.8% and 61.5%, and the ultimate bearing capacity is increased by 42.7% and 68.3%, respectively. The larger the rise-span ratio, the greater the yield load and ultimate bearing capacity of the specimen and the stronger the deformation resistance of circular arch. The numerical simulation on the bending resistance process of circular arch was performed by ABAQUS to present the compression failure process of steel tube and core concrete. The simulation results are in good agreement with the experimental results. The experimental and simulation results show that the circular arch first yields at the inner side of the arch foot, and the curvature of different positions of the specimen is no longer consistent. When the ultimate bearing capacity is reached, the steel pipe at the arch foot obviously heaves, and the hooping effect of the steel pipe on the concrete is invalid. Based on the above research results, a closed composite support scheme of “bolt mesh shotcrete + vertical elliptical CFST support + steel fiber concrete shotcrete layer + reinforced anchor cable” was proposed for the extremely soft rock roadway and successfully applied in the Qingshuiying coal mine.

Study on Compound Mode Crack Propagation Law of Semi Circular Arch Roadway Under Impact Load

Various kinds of defects are usually contained in the underground roadway. When the roadway is impacted by external load, the location of defects will influence the roadway with different degrees. In order to study the effect of the location of defects on crack propagation in roadway, in this paper, the stress wave produced by the bullet impacting the incident rod was used as the impact load. Meanwhile, the variations of speed, displacement and dynamic stress intensity factor (DSIF) of cracks, during crack propagation, were obtained by using the experimental system of digital laser dynamic caustics (DLDC). And the extended finite element software ABAQUS is used for numerical simulation. Based on the method of experimental-numerical simulation, the crack propagation path is verified and the impact fracture behavior of semi-circular arch roadway with different defect positions is presented. It can be concluded that when the prefabricated crack is located at the central axis of sample, the crack propagation belongs to pure mode I; when the prefabricated crack is 5mm away from the central axis, the crack propagation appears between mode I and I-II mixed mode alternately; when the prefabricated crack is at the edge of semi-circular arch roadway, the crack propagation follows I-II mixed mode

The circular arch viaduct: reduce, re-use & recycle in practice

<p>This paper describes a proposal for a Circular Arch Viaduct. The proposal was submitted for a competition for innovation launched by Rijkswaterstaat, the Dutch Directorate-General for Public Works and Water Management, under the title ‘SBIR (Small Business Innovation Research) Circular Viaducts and Bridges’. The authors of this paper are part of a consortium consisting of BESIX NL and Ney &amp; Partners. They have currently rounded up the first phase of the competition (Figure 1).</p><p>Our society has become accustomed to the permanent availability of raw materials; our economy has been running on them for decades. At the same time, the demand for mobility and reliable infrastructure continues to grow. How do we transform the construction industry to use 50% less primary raw materials in 2030 on the way to full 100% circularity in 2050? To answer this question the Circular Arch Viaduct was developed, based on three principles: (1) the reduction of raw materials, (2) the differentiation of materials in function of required strength, and (3) the reduction of waste through re-use and recycling<b>.</b></p><p><br clear="none"/></p><p>Figure 1. The current concept of the Circular Arch Viaduct.</p>