Key Engineering Materials Vol. 517

Abstract: Fabricated hollow slab bridge is commonly used in China. It is indicated that the hinged joints between hollow slabs are easily damaged. Especially under the erosion of chloride salt, the destruction process of hinged joints will be greatly exacerbated. In this paper, deicing salt environment was simulated in the lab to corrode the commonly used hinged joints. According to static load test results, hollow slab coordinated working coefficient is explored and the regression calculation formula was established. Then, the time-varying function of the rate of hinged joint steel corrosion was introduced to the regression model. Finally, the constantly evaluating of the hinged joint durability performance of common used deep, middle and low hinged joint forms were also carried out.

Abstract: Glass fiber reinforced plastics (GFRP) is an immensely versatile material which combines lightweight with inherent strength. For the properties of sustainability, energy efficiency and reduction of CO₂ of GFRP, they can be used in green building as a kind of the energy-efficient and environment-friendly material instead of the conventional materials. Based on the less elastic modulus and lower wave-transparent properties of glass fiber reinforced plastics for unsaturated polyester resin (UPR-FRP), a new kind of glass fiber reinforced plastics based modified unsaturated polyester (MUPR-FRP) was put forward. This paper presents material behavior and technical process of the new MUPR-FRP. For the modified property, the MUPR-FRP members may have the well superiority compare with the steel and the concrete materials used in strengthening engineering and special loading resistance.

Abstract: Based on the research of the new kind of glass fiber reinforced plastics based modified unsaturated polyester (MUPR-FRP). This paper presents the result of the numerical evaluation of bearing behavior of the MUPR-FRP strengthening frame members. The MUPR-FRP strengthening members were modeled using the nonlinear finite element software ANSYS and the load deflection behavior and ultimate capacity were evaluated numerically. For the FE model, members were modeled using Tsai-Wu with tension cut-off failure criterion. The numerical results and the bearing capacity research indicated that the stress of new MUPR-FRP strengthening frame members was less than the load bearing strength and the deformation could satisfy some requirements in use.

Abstract: The thickness or the type of insulating material of cavity wall can be changed in order to satisfy different requirement of thermal insulation properties, so it suits for the hot-summer and cold-winter zone. The static test of 16 pieces of cavity wall with different depth-thickness ratio and different eccentricity has been carried out in this paper, and the failure patterns of the cavity wall, the feature of out-of-plane deformation, the characteristic of vertical deformation and the impact of binding rebar have also been analyzed. As result shows that there is interaction between the interior piece and the external piece of wall under vertical loading which leads to the improvement of the compression capacity. With theoretical analysis, a formula of vertical compression capacity of cavity wall with insulation is proposed. The result calculated by the formula is coincided with the data obtained by the test.

Abstract: The steel roof truss rod is widely used in Chinese building industrue, because of the reasonable force, the design and simple construction, the good economic indicators, attractive appearance and many other advantages. Based on a pin 24m steel roof truss static test research and the results, which is based on the rigid and hinged to calculate, show that the steel roof truss which has the property that the web member axis intersection point and the chord member centroid are coincident, is in a good agreement according the calculation of rigid or hinge compared with the actual stress state.

Abstract: There exist the problems such as low bond strength and bad durability in the ordinary grouting slurry of the ground anchor system at present. The high-performance grouting mediums RPC (Reactive Powder Concrete) and DSP (Densified Systems containing homogeneously arranged ultrafine Particles) would become the potential replacement of grouting medium in ground anchor resulting from their high compressive strength, durability and toughness. Based on a series of pull-out tests on ground anchors with different high-performance grouting medium of RPC and DSP , different bond length in the construction field, the bond performance on the interfaces between anchor bolt (deformed steel bar) and grouted medium as well as between grouted medium and rock mass was studied. The results indicate that the interfacial bond strength between RPC or DSP and deformed steel bolt ranges within 23-31Mpa, far greater than that (about 2-3MPa) between the ordinary cementitious grout and deformed steel bar. Even though the interfacial bond strength between the grouted medium and rock mass of limestone was not obtained in the test since the failure mode was pull-out of those steel bar rather than the interface shear failure between grouted medium and rock mass, the bond stress on the interface reached 6.2-8.38 MPa, also far greater than the bond strength (about 0.1-3MPa) between the ordinary cementitious slurry and rocks.

Abstract: Unprocessed rock is a massive resource of very cheap building material with very low embodied energy. However, it is highly underutilised due to the difficulty of dealing with irregular shaped blocks. We have developed a novel software application using the artificial intelligence methods of search and optimisation to simulate building three-dimensional structures in a virtual world. The aim of our software is to help builders solve the 3-dimensional jigsaw puzzle of building with rock rubble with an emphasis on its potential use for building sustainable housing and infrastructure. This paper describes our approach and the design of our software including an overview of the rock digitising, optimisation software and building methods. We present simulation results of building and testing several small drystone structures using the prototype software.

Abstract: The mix proportion of DSP for the sake of rock anchor grouting has been studied, and the effects of water-binder ratio, volume of nanometer silica added in and various curing methods on the behaviour of the grout have been investigated. Based on the test results, a appropriate proportion of DSP grout with good working and mechanical performance was successfully found.

Abstract: Tilt-up is a method for constructing concrete wall rapidly and economically without formwork. A large number of tilt-up structures have been constructed in North America and other developed countries, and it will also be an acceptable term for new construction in China. Tilt-up process can reduce the cost of labor and materials in wall construction. As the damage of earthquake, the connection of the tilt-up building is the most important part which attracts more attention to engineers. At the end of this paper, details of connection are discussed as the codes introduced.

Abstract: This paper presents a most recent experimental work for evaluating the seismic behaviors of square thin-walled steel tubular columns filled with demolished concrete lumps (DCLs). Fifteen specimens with 300 × 300 mm square section, including 10 columns filled with DCLs and 5 reference columns without DCLs, were tested under combined axial compression and lateral cyclic loading. The parameters considered in the tests are: replacement ratio of DCLs, thickness of steel tube, and axial load ratio. Research findings indicate that the seismic performances of square thin-walled steel tubular columns filled with DCLs are similar to the benchmark columns without DCLs, and the square thin-walled steel tubular columns filled with DCLs also exhibit acceptable ductilities and energy dissipation abilities.