Partially Replacing Fly Ash with Limestone Powder in the Paste - Influence and Characterization
Paste filling is an important research direction of coalmine "green mining" which can dispose coalmines solid waste and achieve environmental protection. The mechanical properties such as compressive strength, workability, ulti- mate tension value, shear strength and splitting strength of paste, in which the fly ash was partially replaced by limestone powder, was studied. Adiabatic temperature rise, setting time, shear strength, permeability, frost resistance and dry shrinkage of different substitution rate were investigated and the results were compared with traditional paste. The test re- sults showed that the influence of limestone powder on workability, permeability and frost resistance performance of paste was slight, the setting time of paste were shortened, adiabatic temperature rise and mechanics performance of paste were decreased, dry shrinkage value was increased with limestone powder content increasing.
Influence of Mass Fractions of Limestone Powder on Mechanical Property and Durability of Concrete
A series of experiments were carried out to investigate the effect of stone powder content and different way of mixture on the workability,different age of compressive strength,modulus of elasticity,drying shrinkage,coefficient of permeability as well as freezingthawing resistance of concrete.The mechanisms of action,the best mass fractions and optimal way of stone powder were analyzed.The studies show that the performance of concrete is the best when the stone power content is between 15% and 20%.
Geometrically Nonlinear Flexibility-Based Frame Finite Element
The paper presents a new element for geometrically nonlinear analysis of frame structures. The proposed formulation is flexibility based and uses force interpolation functions for the bending moment variation that depend on the transverse displacements and strictly satisfy equilibrium in the deformed configuration. The derivation of the governing equations and their consistent linearization are substantially more involved than for stiffness-based elements. Nonetheless, the element offers significant advantages over existing stiffness-based approaches, since no discretization error occurs and all governing equations are satisfied exactly. Consequently, fewer elements are needed to yield results of comparable accuracy. This is demonstrated with the analysis of several simple example structures by comparing the results from flexibility and stiffness-based elements.