Abstract: This paper aims to investigate on producing lightweight aggregates made from the waste stone sludge. It was utilizing the mechanism of high temperature solid solution method as well as in coordination with the production method of reservoir sediments lightweight aggregates to conduct an investigation on the development of lightweight aggregate using stone sludge. The investigation shows that the analysis results for the stone sludge are not in the limits of the expandable region of the ternary diagram due to the high content of FeOx. That caused the expandable temperature range was narrow, the expandability of aggregate was poor and the aggregate particle density was relatively high. But, it still could be producing lightweight aggregates made from the waste stone sludge in this paper. The better solution may be to add the high-content organic materials to adjust chemical composition, such as water purification sludge, sewer sludge, reservoir sludge etc.
Abstract: Precast construction is gaining importance during recent past. Most of the studies reported on precast beam-column joints are to select the appropriate connections to be adopted particularly for regions of low to moderate seismicity. This paper reports on a comprehensive review of literature on the investigations carried out to analyze and evaluate the behaviour of precast concrete structural systems assembled with typical connections or joints under simulated earthquake loading. The seismic performance of precast concrete structure very much depends on the ductility of the joints framed by precast beams and columns. It has been understood that (1) moment resistance beam-column connection and (2) ductile connectors seems to be the most widely used in the precast construction in seismic regions. Further, refinement and research could be carried out in order to optimize such connections to be recommended in low seismicity regions.
Abstract: Beam-column joint in moment resisting frames is very crucial particularly for non-seismically designed cases, which requires strengthening by various methods. This paper reports on shear strength reduction in exterior beam-column joints using haunch elements. Numerical analysis has been performed on exterior beam-column joint of moment resisting frame with and without a haunch element using SAP software. A parametric study has been performed for optimum haunch location (L) along the beam length (Lb) (10%, 12.5%, 15%, 20%, 25%, 40% and 50% of Lb) and the angle of the haunch element along column axis (15°, 30°, 45° and 60°). It has been observed that the optimum location of the haunch element is at 0.2Lb along the beam at an inclination of 45° with the column axis. The analysis results show that the addition of haunch element significantly reduced the joint shear strength.
Abstract: The behaviour of reinforced concrete deep beams is complex due to small shear span-to-depth ratios, which deviates its behaviour from the classical Bernoullis beam behaviour. Such behaviour is predominant in cases where members are supported over small spans carrying heavy concentrated or distributed loads. Such is the case in the structural members like pile cap, transfer girder, panel beam, strap beam in foundation, walls of rectangular water tank, shear wall etc. This paper reports on the influence of Poly propylene fibers combined with and without steel fibers on the stiffness, spall resistance and shear strength of RC deep beams. A total of 21 beams were tested to failure under two-point loading, which were compared with the ACI code provisions. The shear span-to-depth ratios adopted were 0.7 to 0.9 incorporating three steel fiber volume fractions of 0%, 1%, 1.25% along with two different fibers of Steel and Poly propylene with volume fractions of (1.0 + 0.0) %, and (1.0 + 1.0) %. The beams with shear span-to-depth ratios 0.7, 0.8 and 0.9 showed an increase of 21.9%, 23.43% and 23.9% in the ultimate load carrying capacity with combined steel and poly propylene fibers as replacement of web reinforcement with reference to that of the beam without web reinforcement. With the above combinations, the shear strength and stiffness of the beams have been found to be improved. When the horizontal shear reinforcement was increased, the shear strength was found to increase.
Abstract: Cantilever casting construction has been commonly used in construction of continuous rigid frame bridge and the implementation of construction control plays an important role in ensuring the line-type of built bridges and the forced state in construction stage is within the design requirements range. It tends to construct across the winter possibly. Based on an analysis of a typical continuous rigid frame bridge construction stage, this paper takes the impact of winter intermission on pre-camber in construction stage into consideration and the research has guiding significance for the construction of the similar bridge to a certain degree.
Abstract: There is heavy traffic on many expressway bridges in mountainous areas volume, and particularly there are often heavy duty vehicles in the coal-producing regions. Most bridges show different degrees of disease in the operations many years later. Combing the bridge disease investigation, materials inspection and load test done on the background of the interchanges over Yicheng-Houma expressway, this paper will make assessment of the frequently-used box-girder bridges' bearing capacity in the expressway to provide a reference for bearing capacity assessment of the old expressway bridges in mountainous regions.
Abstract: The paper examines the elastic stability of pressed sheet metal flange of a box girder. Mathematical interpretation of elastic stability is performed on the model plate with two freely supported and two elastically restrained edges subjected to combined loads. The research is based on the energy analysis approach, using the principle of minimum deformation energy and the method of cross-sectional girder element decomposition. The plate elastic stability mechanism is investigated in an interactive environment that simulates local loads and compressive longitudinal forces produced by global stress. The significant geometric parameters, as well as support and load conditions affecting the loss of stability, are identified. The research results can be applied as a constraint on the local flange stability in the optimization of box girders.
Abstract: Optimal prioritization of maintenance and rehabilitation (M&R) activities for pavement sections can enable significant time and cost-savings. In this study, we used the particle swarm optimization (PSO) method to achieve optimal prioritization of 135 pavement sections based on eight pavement condition parameters. The parameters included standard deviation (SD) for smoothness, rutting, deflections, cracking, pothole, bleeding, patching, and shoving. SD for smoothness, rutting, and deflections were inspected using instruments, while cracking, pothole, bleeding, patching, and shoving were surveyed visually. The PSO method was used to quickly calculate the synthetic pavement condition for each pavement section and then obtain the optimal prioritization of pavement sections. With this approach, pavement engineers are able to efficiently perform appropriate and timely M&R activities for pavement sections, according to their priority. This study provides an alternative solution to current approaches for prioritization of pavement sections.
Abstract: Artificial cementation is a technique commonly used to improve the mechanical properties of soils for use in geotechnical engineering works, because it often provides economic and environmental advantages. In order to study the factors that influence the behavior of cemented dune sand from Natal, series of unconfined compression and splitting tension tests were performed. These tests showed that increasing the cement content and decreasing void ratio are effective ways to improve compressive strength. The same applies to tensile splitting strength. It was also established that both unconfined compressive and splitting tensile strengths can be related to a quotient between volume of void-space and cement content.