Abstract
The AEC industry is highly interested in effective ICT adoption and deployment, including its utilization within the design process. However, its capabilities have not yet been fully exploited and it is an obvious area for further research. Architects and engineers tend to have some technological support to monitor and evaluate the possible impacts of decisions made throughout the design process. Many aspects are left out of consideration and the entire project is broken up into independent fragments or domains that are combined together at a later, post hoc stage. Impact of separate decisions on each others have to be interpreted on a person-to-person basis between the involved design stakeholders.
This paper attempts to evaluate current design practice and associated challenges towards design integration with advanced technologies, such as BIM, by conducting an online survey targeted at designers and engineers, who are most affected by its emerging issues. The outcomes of this study are presented and analysed, concluding that the current design process fails to meet expectations and needs improvements. It goes further to propose the requirements for an integrated system as a means for an effective solution for the identified problem.
Key Words
integrated design; evaluation; current practice; integrated platform; online survey; designers
Address
Abdelaziz H. Fadoul and Walid Tizani: Centre for Structural Engineering and Informatics (CSEI), Faculty of Engineering, University of Nottingham, Coates Building, NG7 2RD, Nottingham, United Kingdom
Abstract
The Micro circular diaphragm (MCD) is the mechanical actuator part used in the micro electro-mechanical sensors (MEMS) that combine electrical and mechanical components. These actuators are working under harsh mechanical and thermal conditions, so it is very important to study the mechanical and thermal behaviors of these actuators, in order to do with its function successfully. The objective of this paper is to determine the thermo-mechanical behavior of MCD by developing the traditional bulge test technique to achieve the aims of this work. The specimen is first pre-stressed to ensure that is no initial deflection before applied the loads on diaphragm and then clamped between two plates, a differential pressure (P) and temperature (Tb) is leading to a deformation of the MCD. Analytical formulation of developed bulge test technique for MCD thermo-mechanical characterization was established with taking in-to account effect of the residual strength from pre-stressed loading. These makes the plane-strain bulge test ideal for studying the mechanical and thermal behavior of diaphragm in both the elastic and plastic regimes. The differential specimen thickness due to bulge effect to describe the mechanical behavior, and the temperature effect on the MCD material properties to study the thermal behavior under deformation were discussed. A finite element model (FEM) can be extended to apply for investigating the reliability of the proposed bulge test of MCD and compare between the FEM results and another one from analytical calculus. The results show that, the good convergence between the finite element model and analytical model.
Key Words
bulge test; thermo-mechanical behavior; micro circular diaphragm; finite-element analysis; and MATLAB software
Address
Wael A. Altabey:
1) International Institute for Urban Systems Engineering, Southeast University, 210096, Nanjing, China
2) Department of Mechanical Engineering, Faculty of Engineering, Alexandria University, 21544, Alexandria, Egypt
Abstract
Collapse was one of the typical common geological hazards during the construction of tunnels. The risk assessment of collapse was an effective way to ensure the safety of tunnels. We established a prediction model of collapse based on Bayesian Network. 76 large or medium collapses in China were analyzed. The variable set and range of the model were determined according to the statistics. A collapse prediction software was developed and its veracity was also evaluated. At last the software was used to predict tunnel collapses. It effectively evaded the disaster. Establishing the platform can be subsequent perfect. The platform can also be applied to the risk assessment of other tunnel engineering.
Key Words
76 large or medium collapses; Bayesian Network; prediction model of collapse; collapse prediction software; engineering application
Address
Jing WANG, Shucai LI, Liping LI, Shaoshuai SHI, Zhenhao XU and Peng LIN: Research Center of Geotechnical and Structural Engineering, Shandong University, Jinan 250061, China
Abstract
This study aimed to investigate the effect of initial member length an imperfection in the load carrying capacity of double-layer domes space structures. First, for the member length imperfection of each member, a random number is generated from a normal distribution. Thereupon, the amount of the imperfection randomly varies from one member to another. Afterwards, based on the Push Down analysis, the collapse behavior and the ultimate capacity of the considered structure is determined using nonlinear analysis performed by the OpenSees software and this procedure is repeated numerous times by Monte Carlo simulation method. Finally, the reliability of structures is determined. The results show that the collapse behavior of double-layer domes space structures is highly sensitive to the random distribution of initial imperfections.
Key Words
reliability; Monte Carlo simulation method; progressive collapse; imperfection; double layer
grids; space structures; domes
Address
Mehrdad Gordini, Mohammad Reza Habibi and Mehrzad Tahamouliroudsari: Department of civil Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
Mohammad Reza Sheidaii: Department of Civil Engineering, College of Engineering, Urmia University, Urmia, Iran
Abstract
Over the past couple decades, externally bonded fiber reinforced polymer (FRP) composites have emerged as a repair and strengthening material for many concrete infrastructure applications. This paper presents an analytical investigation of the use of carbon FRP (CFRP) for a specific problem that occurs in concrete bridge girders wherein the girder ends are damaged by excessive exposure to deicing salts and numerous freezing/thawing cycles. A 3D finite element (FE) model of a full scale prestressed concrete (PC) I-girder is used to investigate the effect of damage to the cover concrete and stirrups in the end region of the girder. Parametric studies are performed using externally bonded CFRP shear laminates to determine the most effective repair schemes for the damaged end region under a short shear span-to-depth ratio. Experimental results on shear pull off tests of CFRP laminates that have undergone accelerated aging are used to calibrate a bond stress-slip model for the interface between the FRP and concrete substrate and approximate the reduced bond stress-slip properties associated with exposure to the environment that causes this type of end region damage. The results of these analyses indicate that this particular application of this material can be effective in recovering the original strength of PC bridge girders with damaged end regions, even after environmental aging.
Key Words
finite element; prestressed concrete; FRP; repair; bridge girder; end region
Address
Ian D. Shaw and Bassem Andrawes: Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 N. Mathews, Urbana, IL 61801, USA
Abstract
This paper shows optimal dimensioning for the corner combined footings to obtain the most economical contact surface on the soil (optimal area), due to an axial load, moment around of the axis X and moment around of the axis Y applied to each column. The proposed model considers soil real pressure, i.e., the pressure varies linearly. The classical model is developed by trial and error, i.e., a dimension is proposed, and after, using the equation of the biaxial bending is obtained the stress acting on each vertex of the corner combined footing, which must meet the conditions following: 1) Minimum stress should be equal or greater than zero, because the soil is not withstand tensile. 2) Maximum stress must be equal or less than the allowable capacity that can be capable of withstand the soil. Numerical examples are presented to illustrate the validity of the optimization techniques to obtain the minimum area of corner combined footings under an axial load and moments in two directions applied to each column.
Key Words
corners combined footings; optimization techniques; contact surface; more economical dimension; optimal area
Address
Sandra López-Chavarría, Arnulfo Luévanos-Rojas and Manuel Medina-Elizondo: Institute of Multidisciplinary Researches, Autonomous University of Coahuila, Blvd. Revolución No. 151 Ote, CP 27000, Torreón, Coahuila, México
