Advanced Materials Research Vols. 243-249

Abstract: The suspendome structure is a new-type of hybrid prestressed spatial structural system which has been developing on the basis of single-layer latticed shell structure and cable dome structure. The wide application prospects of this type of structure have been presented initially since its emergence around ten years ago. Several representative engineering applications of suspendome structures are introduced, and the research status of this structure at home and abroad is summarized. Moreover, further research orientations of suspendome structures are discussed and prospected.

Abstract: In order to improve the bearing capacity of SRC which is related with deformation and stiffiness, SRC beams should be strengthened by CFRP. Based on the experiment of six pre-splitting steel reinforced concrete beams strengthened with (Prestressed) CFRP sheets, the deformation of beams are discussed. Load-deformation curves are obtained by the experiment. Considering the influence of intial bending moment on SRC beams, the calculated deformation formulas of SRC beams strengthened by (Prestressed) CFRP are deduced. The results showed that the load-deformation curves of normal and strengthened beams respectively showed three and two linear characteristics. The theoretical results which calculated by the formulas of deformation are well agreement with the experimental results.

Abstract: As for the form of a earth buildings ,rammed earth buildings have the advantages of green and environmental protection, easy and fast construction, low cost. This paper analyzes the raw material requirements ,structural types , construction technology and inspection of rammed earth buildings, focusing on the discussion of the quality inspection methods to provide a reference for the construction of rural residential adobe buildings.

Abstract: To research the safety of an underground defense project and the impact to other buildings, applying basic mechanics principles, established two types of mathematical model for arch about the project, and analyzed stress in different directions of ground arch structure. The data shows that the results were very different in different mathematical models, and mathematical models should be considered as close to actual stress situation in structural analysis. In the structural analysis involved soil, spatial finite element model is more accurate and reasonable than truss finite element model.

Abstract: End plate stiffener failures occure in a number of tests in recent years. And no relevant rules are given in design codes for steel structures. A design method for angles and thickness of stiffeners in extended end plate connecionts is derived by requiring the eqaul distribution of tensile force among bolts inside and outside of beam flange. And a balance between the force transmitted by the stiffener and by the beam flange is considered too. Comparisons with results of ANSYS show that the stiffeners designed by the proposed method in this paper are able to change the extended portion of endplates from one side clamped to 2 panels fixed on two adjacent sides. Simple formulas for calculating rotational rigidities of the connections with and/or without stiffeners were also proposed with component method, in which the end-plate stiffness, column flange stiffness and bolt stiffness are inclueded. Comparisons with results of ANSYS show that the proposed equations have good precision and can be applied to pratical engineering.

Abstract: Based on the experiments of four connections with widened beam flange section which included two arc widened beam flange connections and two welded side-plate connections specimens and one ordinary connection under cyclic loading, 3-D nonlinear finite element models were created by using ANSYS software to analyze the mechanical properties of these two types of widened beam flange connections, such as skeleton curve, ultimate load, ductility and failure mode etc. The analytical results show good agreement with those of the experiments and prove the finite models correct and applicable. According to the experimental and element analytical failure results, the PI(PEEQ Index) was introduced to investigate the plasticity development and fracture tendency at the end of the widened flange part . Furthermore, the failure patterns of widened beam flange connection were revealed.

Abstract: In order to improving the launching technique in soft layer, the paper proposed the soil-chamber under pressure on the launching technique basing on engineering practices. The main principle is: using the earth pressure equilibrium, grouting the filling material when the Shield launching, establishing the active earth pressure ahead of time, which makes in advance the action pressure supports to the coarse sand cross section, that prevents from the water and soil spouting effectively. Because the active earth pressure, enhance the initial sending safety coefficient, and shorten the reinforcement length of the initial launching, and decrease the initial launching cost.

Abstract: In this paper, the force against rigid retaining walls from backfill soil under static loads and vibration loads is analyzed within three cases. The first case is an ordinary retaining wall without expanded polystyrene (EPS) geofoam buffer. In the second and the third case, a layer of vertical EPS buffer with different density and elastic modulus is placed between a rigid retaining wall and backfill soil. Numerical simulation results show that the force against the same retaining wall in the treated cases is less than that in the untreated case, under both static loads and vibration loads. Moreover, the compression of different EPS buffer is studied. Under vibration excitation, when the density and elastic modulus of EPS buffer decreases, its compression increases and more wall force is mitigated. Simulation results accord with the physical shaking table test data. Numerical results and physical test demonstrate that EPS geofoam seismic buffers hold great promise to reduce loads against rigid retaining wall structures, especially earthquake-induced dynamic loads.

Abstract: This paper presents the development of a new remediation technology of contaminated soil and groundwater using humic acid (HA) in permeable reactive barrier (PRB) for pipeline leakage. The objective of this study was to use humic acid that could be medium within a PRB to filter complex contaminated soil and groundwater containing chromium. Leakage of pollutants (such as hydrocarbon、gasoline、oil、wastewater、heavy metal et al) has a large economic and environmental impact. When a pipeline leak is large or undiscovered for a longer period of time, substantial volumes of gases and liquids can leak into the soil and groundwater, which can develop into dangerous situations involving costly remediation works. Traditional methods for remedying contaminated soil and groundwater from pipeline leakage, such as drilling and geochemical analysis, are destructive, time consuming and expensive. A PRB was determined to be the best option for remedying groundwater that has become contaminated with a wide range of organic contaminants (i.e., benzene, toluene, methylbenzene, xylene and polyaromatic hydrocarbons), heavy metals (i.e., lead and arsenic). PRB is installed in or down gradient from the flow path of a contaminant plume. The contaminants in the plume react with the media inside the barrier to either break the compound down into harmless products or immobilize contaminants by precipitation or sorption. It is made up of humic acid that reduce contaminants. With the development of industry and agriculture, environmental contamination has become more and more serious, especially heavy metal pollution, have been a major environmental issue, drawing much scientific and public attention. Chromium is identified as “priority pollutant” by the United States Environment Protection Agency (US EPA). the measurements show a significant increase of the adsorption of Cr (VI) because of the complexion reaction between HA and Cr (VI) occurred under acidic condition. It could be concluded that HA could be used effectively on remediation of Cr (VI)-contaminated soil and groundwater in a wide range of pH, with or without sunlight.

Abstract: Nowadays, damping is still the important dynamic characteristic that is the least understood and the most difficult to quantify. The advantage of the proposed damping matrix identification method is that several low order complex modes achieved by Experimental Modal Analysis (EMA) are capable of calculation precision. In order to identify the damping matrix, this paper also proposes a general damping matrix decompositon technique, which can be used in the situation that different parts of the structure have different damping. Then a five-story frame structure is applied to demonstrate the proposed method ,and the results obtained show the suitability of this approach for damping matrix identification in frame structures.