The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
B Venkatarama V Reddy - One of the best experts on this subject based on the ideXlab platform.
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moisture transport in cement stabilised soil brick mortar interface and implications on Masonry bond strength
2019Co-Authors: B Venkatarama V Reddy, Vineeta Nikhil, M NikhilashAbstract:Interfacial bond development between Masonry Unit and the mortar is due to mechanical interlocking of cement hydration products into the brick pores. The paper presents results of investigations on moisture transport from fresh mortar bed to the cement-stabilised soil brick (CSSB) and its implications on the CSSB Masonry bond strength. Three types of mortars (cement mortar, cement-lime mortar and cement-soil mortar) and one type of CSSB were considered in the experiments. The results show that the CSSB’s absorb moisture rapidly in the initial soaking period and attain 75% saturation in about 20 min. The fresh mortars loose considerable amount of water due to brick suction and the water–cement ratio reduces drastically in the initial one hour of contact with the bricks. Use of partially saturated (50–75%) CSSB’s for Masonry construction yield maximum bond strength and is therefore recommended.
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prediction of solid block Masonry prism compressive strength using fe model
Materials and Structures, 2010Co-Authors: Ch Uday V Vyas, B Venkatarama V ReddyAbstract:Masonry strength is dependent upon characteristics of the Masonry Unit, the mortar and the bond between them. Empirical formulae as well as analytical and finite element (FE) models have been developed to predict structural behaviour of Masonry. This paper is focused on developing a three dimensional non-linear FE model based on micro-modelling approach to predict Masonry prism compressive strength and crack pattern. The proposed FE model uses multi-linear stress–strain relationships to model the non-linear behaviour of solid Masonry Unit and the mortar. Willam–Warnke’s five parameter failure theory developed for modelling the tri-axial behaviour of concrete has been adopted to model the failure of Masonry materials. The post failure regime has been modelled by applying orthotropic constitutive equations based on the smeared crack approach. Compressive strength of the Masonry prism predicted by the proposed FE model has been compared with experimental values as well as the values predicted by other failure theories and Eurocode formula. The crack pattern predicted by the FE model shows vertical splitting cracks in the prism. The FE model predicts the ultimate failure compressive stress close to 85% of the mean experimental compressive strength value.
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influence of shear bond strength on compressive strength and stress strain characteristics of Masonry
Materials and Structures, 2008Co-Authors: B Venkatarama V Reddy, Ch Uday V VyasAbstract:The paper is focused on shear bond strength–Masonry compressive strength relationships and the influence of bond strength on stress–strain characteristics of Masonry using soil–cement blocks and cement–lime mortar. Methods of enhancing shear bond strength of Masonry couplets without altering the strength and modulus of Masonry Unit and the mortar are discussed in detail. Application of surface coatings and manipulation of surface texture of the Masonry Unit resulted in 3–4 times increase in shear bond strength. After adopting various bond enhancing techniques Masonry prism strength and stress–strain relations were obtained for the three cases of Masonry Unit modulus to mortar modulus ratio of one, less than one and greater than one. Major conclusions of this extensive experimental study are: (1) when the Masonry Unit modulus is less than that of the mortar, Masonry compressive strength increases as the bond strength increases and the relationship between Masonry compressive strength and the bond strength is linear and (2) shear bond strength influences modulus of Masonry depending upon relative stiffness of the Masonry Unit and mortar.
Ch Uday V Vyas - One of the best experts on this subject based on the ideXlab platform.
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prediction of solid block Masonry prism compressive strength using fe model
Materials and Structures, 2010Co-Authors: Ch Uday V Vyas, B Venkatarama V ReddyAbstract:Masonry strength is dependent upon characteristics of the Masonry Unit, the mortar and the bond between them. Empirical formulae as well as analytical and finite element (FE) models have been developed to predict structural behaviour of Masonry. This paper is focused on developing a three dimensional non-linear FE model based on micro-modelling approach to predict Masonry prism compressive strength and crack pattern. The proposed FE model uses multi-linear stress–strain relationships to model the non-linear behaviour of solid Masonry Unit and the mortar. Willam–Warnke’s five parameter failure theory developed for modelling the tri-axial behaviour of concrete has been adopted to model the failure of Masonry materials. The post failure regime has been modelled by applying orthotropic constitutive equations based on the smeared crack approach. Compressive strength of the Masonry prism predicted by the proposed FE model has been compared with experimental values as well as the values predicted by other failure theories and Eurocode formula. The crack pattern predicted by the FE model shows vertical splitting cracks in the prism. The FE model predicts the ultimate failure compressive stress close to 85% of the mean experimental compressive strength value.
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influence of shear bond strength on compressive strength and stress strain characteristics of Masonry
Materials and Structures, 2008Co-Authors: B Venkatarama V Reddy, Ch Uday V VyasAbstract:The paper is focused on shear bond strength–Masonry compressive strength relationships and the influence of bond strength on stress–strain characteristics of Masonry using soil–cement blocks and cement–lime mortar. Methods of enhancing shear bond strength of Masonry couplets without altering the strength and modulus of Masonry Unit and the mortar are discussed in detail. Application of surface coatings and manipulation of surface texture of the Masonry Unit resulted in 3–4 times increase in shear bond strength. After adopting various bond enhancing techniques Masonry prism strength and stress–strain relations were obtained for the three cases of Masonry Unit modulus to mortar modulus ratio of one, less than one and greater than one. Major conclusions of this extensive experimental study are: (1) when the Masonry Unit modulus is less than that of the mortar, Masonry compressive strength increases as the bond strength increases and the relationship between Masonry compressive strength and the bond strength is linear and (2) shear bond strength influences modulus of Masonry depending upon relative stiffness of the Masonry Unit and mortar.
Alex Hakchul Shin - One of the best experts on this subject based on the ideXlab platform.
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finite element study on the impact responses of concrete Masonry Unit walls strengthened with fiber reinforced polymer composite materials
Composite Structures, 2016Co-Authors: Dongkeun Lee, Alex Hakchul ShinAbstract:Abstract Research on the impact behaviour of concrete Masonry Unit (CMU) walls strengthened with fiber-reinforced polymer (FRP) composites is considerably limited. In this study, the effectiveness of externally bonded (EB) FRP technique on the resistance of CMU walls under high-velocity impact force was therefore investigated numerically. Finite element (FE) models were developed using LS-DYNA. The Concrete Damage Rel3 model and Enhanced Composite Damage material models were used for concrete and composite materials, respectively. Furthermore, the Add Erosion and Smooth Particle Hydrodynamics options were included to accurately represent impact behaviour. The FE models were validated using literature results. Applications of various EB FRP composites to CMU walls were investigated with the parameters of fiber types, fiber direction, fiber layer, and impactor velocity. The numerical results show that the EB FRP strengthening technique is significantly effective to improve the impact resistance of CMU walls by preventing an impactor from perforating the CMU walls.
Stanley C. Woodson - One of the best experts on this subject based on the ideXlab platform.
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Blast Response of Lightly Attached Concrete Masonry Unit Walls
Journal of Structural Engineering-asce, 2005Co-Authors: James T. Baylot, Billy Bullock, Thomas R. Slawson, Stanley C. WoodsonAbstract:Exterior wall panels of structures are often constructed of concrete Masonry Units (CMUs), commonly known as concrete blocks. These walls may become a debris hazard to building occupants when high explosives, for example, a terrorist vehicle bomb, are detonated outside of a building. A recently completed series of physical experiments is being used to develop methods for predicting the hazard levels associated with CMU walls. Retrofitting techniques have been developed to mitigate these hazards. The experiments included nonretrofitted CMU walls as well as several different types of retrofits. Test data, high-speed video, and posttest inspection of the experiments were used to assess the parameters that affect the response of CMU walls and retrofit systems. The objective of the research presented in this paper is to collect data on the blast response of CMU walls so that improvements can be made to the previously developed Wall Analysis Code (WAC).
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response of 1 4 scale concrete Masonry Unit cmu walls to blast
Journal of Engineering Mechanics-asce, 2002Co-Authors: Scott T Dennis, James T. Baylot, Stanley C. WoodsonAbstract:The exterior walls of conventional structures are often constructed using concrete Masonry Units (CMUs), commonly called concrete blocks. A series of experiments was conducted at the U.S. Army Engineer Research and Development Center to determine the response of a one-way 14-scale CMU wall to the detonation of an explosive charge. Finite-element analyses were developed to predict the results of these experiments. Each CMU was modeled with eight-node continuum elements. Adjacent CMUs were tied together using a slide surface that models a rigid connection until a failure criterion is met. Based on the analyses, a charge standoff was selected to induce a near-failure response. Five blast-load experiments were conducted. Both pre- and posttest analyses compare reasonably well with experimental results.
Peter Schuderer - One of the best experts on this subject based on the ideXlab platform.
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Rolling-reactive Optimization of Production Processes in a Calcium Silicate Masonry Unit Plant Using Online Simulation
Procedia CIRP, 2018Co-Authors: Toni Donhauser, Tobias Ebersbach, Jörg Franke, Peter SchudererAbstract:Abstract In case of concatenated, complex material flow structures such as those in calcium silicate Masonry Unit plants, plan deviations pose a major challenge for an efficient order processing in production. In order to overcome the separation between the planning and operational levels in traditional production planning and control systems, this paper presents a validated concept to react immediately to critical events while maintaining efficiency using a modular, rolling-reactive optimization tool. A substantial difference to conventional rescheduling models is the intensive integration of event-discrete simulation, which delivers more realistic results and reduces the threat of an obsolete model due to simple modelling.
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efficient method for optimizing calcium silicate Masonry Unit manufacturing using simulation based optimization and decomposition
Applied Mechanics and Materials, 2016Co-Authors: Toni Donhauser, Jörg Franke, Joachim Lohse, Peter SchudererAbstract:This paper describes an overall, simulation-based optimization approach to control plant operations for manufacturing calcium silicate Masonry Units (CS), which is directed towards and thus immediately applicable to practical processes. Starting from an investigation and classification of the CS production in order to differentiate the properties of each sub-process, specific target criteria are derived. To enable the influencing of these targets, relevant parameters including their mutual interdependencies are identified. On this basis, the criticality of each process step is assessed in order to determine improvement potentials and to investigate possible adjustments to the parameters.The elementary production types indicate a mix of the discontinuous and continuous processing in CS plants. Particularly, this work shows that through interrupting the continuous material flow, the hardening process is the main criteria for a plant’s success in meeting its targets, especially concerning energy efficiency. To achieve a feasible approach, the work develops a solving method geared to an optimized hardening process.Therefore, a formulation of a measureable target system is established, which is the prerequisite for modeling the whole optimization problem. An expedient decomposition of this optimization model to smaller sub-problems provides an efficient solving of these complex job-scheduling problems, in order to direct the method towards an operative use. The paper concludes with the determination of potential solving procedures for the overall problem and appropriate algorithms for solving the sub-problems.
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Valid Methodology for Using Discrete Event Simulation to Improve the Resource Consumption for the Manufacturing of Masonry Units
Procedia CIRP, 2016Co-Authors: Toni Donhauser, Peter Schuderer, Tobias Rackow, Johannes Hirschbrunn, Jörg FrankeAbstract:Abstract Owing to a high inflexibility of the factory layout, manufacturers of Masonry Units are bound to organizational adjustments seizing optimization measures. Regarding such plants, having a given complexity based on a rigid concatenation of heterogeneous sub-processes with heavy goods to be transported, conventional measures such as Lean Management principles involve great efforts in execution. Therefore, an IT solution for planning and controlling the operational processes is to be developed. This solution will be implemented through simulation-supported optimization to support dealing with a higher complexity and setting up a more resource-efficient manufacturing process. As a basis, a corresponding factory is mapped sufficiently accurate in every detail in a discrete event analysis (DEA) model. In this paper, a methodology, how to configure an arbitrary calcium silicate Masonry Unit (CS) plant in a simulation model, is presented for the first time. Relevant data is cataloged and modelling approaches for the controlling methods are pointed out. Special regard is paid to optimization measures at the crucial point of the transition from bulk material to piece goods, which has not been regarded yet in discrete event simulation modelling. The major aspect is a comparison of a Unit-based approach and a variable-controlled approach, regarding the runtime. A case study follows conclusively, which aided in validating the methodology by simulating various scenarios. As a result, several strategic and operational optimization potentials were identified.