Vladimir G. Haach

Experimental Analysis of Reinforced Concrete Block Masonry Walls Subjected to In-Plane Cyclic Loading

An innovative system for reinforced concrete masonry walls based on the combination of vertical and horizontal trussed reinforcement is proposed. The mechanical characterization of the seismic behavior of such reinforced masonry walls is based on static cyclic tests carried out on panels with appropriate geometry. The influence of the factors influencing the in-plane cyclic behavior of concrete masonry walls, such as the horizontal reinforcement, precompression, and masonry bond pattern, is discussed. The results are analyzed in terms of failure modes and force versus displacement diagrams, from which the seismic performance is assessed based on the ductility and energy capacity dissipation. The results stressed that the increase on the precompression level leads to a stiffer and more brittle lateral behavior of the masonry walls. The presence of horizontal reinforcement ensures better control and better distribution of cracking, even if only a marginal increase of lateral strength was found in the particular testing program.

Assessment of compressive behavior of concrete masonry prisms partially filled by general mortar

The usage of general mortar for embedding and partially filling units in masonry prisms was evaluated through compressive tests. Filled and unfilled prisms were tested to verify the differences in their compressive behavior. Four mortar mixes with three water/cement ratios for each mix were used in tests. Results indicated small differences between filled and unfilled masonry prisms. Mortar had a slight effect on the compressive strength of the masonry. A more significant effect, however, could be observed on secant elastic modulus, compressive fracture energy and deformations of masonry prisms. An analytical model to represent the stress versus strain diagram of masonry prisms was proposed which depends on the compressive strength of mortar and masonry prisms. Furthermore, results indicate that the use of general mortar for embedding and filling masonry prisms can offer a solution in terms of building technology.

Proposal of a Design Model for Masonry Walls Subjected to In-Plane Loading

AbstractMasonry walls subjected to in-plane loading exhibit a complex behavior because of the influence of several parameters such as axial load, aspect ratio, and the strength of materials. In high-rise buildings or seismic areas, large tensile stresses may arise in these walls, and vertical and horizontal reinforcement is often used to provide proper resistance, which increases the complexity of the structural behavior. This work presents (1) an overview of the experimental behavior of unreinforced and reinforced masonry walls; (2) an overview of distinct design methods aimed at calculating the in-plane lateral resistance; and (3) a proposal of a new design model for reinforced masonry walls subjected to in-plane loading. The proposed model considers the coupling interaction of the flexural and shear resisting mechanisms and updates the role of the vertical and horizontal reinforcement to the lateral resistance. A database composed of experimental results of the in-plane lateral resistance of 101 masonr...

Improved Construction of Concrete Viaducts with Movable Scaffolding Systems in Spain

The current paper relates the state of the art of construction of viaducts with a movable scaffolding system (MSS). Two different procedures are introduced: the traditional sequence and the new sequence applied to some viaducts in Spain. The traditional sequence consists of two phases: first, concreting the bottom slab and webs, and then concreting the top slab of the deck. Once the first and second casting phases are completed, the total prestressing force is introduced. The new sequence consists of concreting a self-supporting core (i.e., the bottom slab, webs, and only a portion of the top slab). Once the self-supporting core has hardened, a partial prestressing force is introduced so that the scaffolding can be advanced to the next span; the central zone of the top slab is cast in a second phase. Both sequences are described here with their constructive peculiarities and issues.

Dependency of modeling parameters for the construction of influence surfaces by the finite element method

The concept of influence surface has been largely used for the determination of the internal forces of bridge decks. Differently from the load that acts on usual building structures in bridge decks, those loads are in movement; therefore, a more careful evaluation must be conducted for the determination of the maximum efforts. Equilibrium, Müller-Breslau and Adjoint methods are alternative methodologies for the construction of influence surfaces. This manuscript addresses the implementation of such methods through the finite element method and the application of influence surfaces for the obtaining of internal forces. Parameters, as mesh density and shape functions of finite elements are explored through a numerical example. The results show the three procedures provided similar influence coefficients for shear and bending moments, in nodes distant from the reference point and very sensitive values to the mesh density and shape functions of finite elements in the reference point. The convergence values found for the internal forces calculated with the distributed load of the wheel did not show a strong dependency on the parameters under analysis.