Shear modulus and stiffness of brickwork masonry: An experimental perspective
Masonry is a composite non-homogeneous structural material, whose mechanical properties depend on the properties of and the interaction between the composite components - brick and mortar, their volume ratio, the properties of their bond, and any cracking in the masonry. The mechanical properties of masonry depend on the orientation of the bed joints and the stress state of the joints, and so the values of the shear modulus, as well as the stiffness of masonry structural elements can depend on various factors. An extensive testing programme in several countries addresses the problem of measurement of the stiffness properties of masonry. These testing programs have provided sufficient data to permit a review of the influence of different testing techniques (mono and bi-axial tests), the variations caused by distinct loading conditions (monotonic and cyclic), the impact of the mortar type, as well as influence of the reinforcement. This review considers the impact of the measurement devices used for determining the shear modulus and stiffness of walls on the results. The results clearly indicate a need to re-assess the values stated in almost all national codes for the shear modulus of the masonry, especially for masonry made with lime mortar, where strong anisotropic behaviour is in the stiffness properties.
A Comparative Experimental Study of the Modulus of Elasticity of Bricks and Masonry .
One of the parameters identified as influencing the structural response of buildings is the dynamic Modulus of Elasticity of masonry. The Longitudinal Vibration Test Method and the Ultrasonic Pulse Methods were developed for the dynamic testing of ooncrete specimens. These two dynamic procedures are to be tested on masonry prisms to provide a verification of the methods. The first aim of this paper is to experimentally investigate the use of high frequency sinusoidal dynamic loading to determine the dynamic Modulus of Elasticity of masonry. The second aim is to compare the dynamic . Modulus ofElasticity results to the Young's Modulus obtained using quasi-static methods. The third aim is to compare the masonry prism results to masonry unit results for the Young' s Modulus, to determine the ratio of Young' s Modulus to the peak stress for the prisms and to calculate the Young' s Modulus for the mortar. A test rig has been developed for measuring the elastic properties of masonry prisms under uni axial static loading. The dynamic and quasi-static samples were tested from the same population of masonry prism samples. A single type of mortar was used for ali experimental work.
When to Cross the Spread? Trading in Two-Sided Limit Order Books
In this paper the problem of optimal trading in illiquid markets is addressed when the deviations from a given stochastic target function describing, for instance, external aggregate client flow are penalized. Using techniques of singular stochastic control, we extend the results of [F. Naujokat and N. Westray, Math. Financ. Econ., 4 (2011), pp. 299--335] to a two-sided limit order market with temporary market impact and resilience, where the bid ask spread is now also controlled. In addition to using market orders, the trader can also submit orders to a dark pool. We first show existence and uniqueness of an optimal control. In a second step, a suitable version of the stochastic maximum principle is derived which yields a characterization of the optimal trading strategy in terms of a nonstandard coupled forward-backward stochastic differential equation (FBSDE). We show that the optimal control can be characterized via buy, sell, and no-trade regions. The new feature is that we now get a nondegenerate no-...