Petros Christou

An economic analysis of Cyprus’ residential buildings’ energy retrofits potential

Cyprus’ building stock energy saving potential is considerably high due to the absence of legislation and regulations governing the energy performance of buildings, prior to the countrys accession to the European Union. In this study, a methodology is proposed and applied to a typical residential building to assess the financial attractiveness of alternative retrofit scenarios. An advanced simulation software tool is utilised to measure the energy performance of a typical residential building in terms of envelope characteristics, construction materials and Heating, Ventilation and Air Conditioning system. The thermal model is used to assess the impact of alternative retrofitting scenarios. Then, an economic model is developed to evaluate the financial impact over the investment horizon. Finally, a risk analysis is conducted to investigate the stochastic behaviour of key input variables.

Implementing slack cables in the force density method

Purpose – The purpose of this paper is to present a solution strategy for the analysis of cable networks which includes an extension to the force density method (FDM) in an attempt to support cable elements when they become slack. The ability to handle slack cable elements in the analysis is particularly important especially in cases where the original cable lengths are predefined, i.e. the cable structure has already been constructed, and there is a need for further analysis to account for additional loading such as wind. The solution strategy is implemented in a software application. Design/methodology/approach – The development of the software required the implementation of the FDM for the analysis of cable networks and its extension to handle constraints. The implemented constraints included the ability to preserve the length in the stressed or the unstressed state of predefined cable elements. In addition, cable statics are incorporated with the development of the cable equation and its modification ...

Quality evaluation of residential houses: the development of a real-time quality assessment tool

The construction industry has been heavily affected by the economic crisis. Product differentiation and cost reduction through improved qualities could be the way out. However, applying quality control to the construction industry is a challenging task since construction projects are highly customised, constituting the application of statistical process control principles extremely difficult. This paper presents the constituting elements of a real-time quality assessment tool for the residential housing sector. It has been designed to be used primarily for internal company purposes. In particular, utilising the tool for assessing, in real-time, the quality of the projects currently in-progress and comparing the quality of completed projects and consequently drawing conclusions about the company’s quality progress. The tool’s structure comprises of 1a model of the construction process 2a checklist 3a quality scoring algorithm 4an application methodology 5an accompanied software tool. The forthcoming challe...

A Real-Time Quality Assurance Tool for the Cyprus Construction Industry

Abstract Current economic crisis severely affected construction industry across the Globe. Major construction companies seek product differentiation through improved quality. However, Quality Assurance applied to the construction industry proves to be a challenging task since construction projects are highly customised constituting application of Statistical Process Control principles extremely difficult. Within this context, this paper presents the ongoing activities relating to the development of a real-time quality assurance tool for the Cyprus construction industry. The framework of this tool comprises of (a) a model of the construction process, (b) a list of construction processes, (c) a checklist and (d) an application methodology. Further work to the tool completion is also described.

The Evolution of Analysis Methods for Laterally Loaded Piles Through Time

Today’s structures impose a higher demand on their foundations as their height increases and their designs are more daring and complex. Naturally, the use of pile foundations, which provide the means for transferring the loads to greater depths, is increasing. Despite the advances in the construction of such foundations as well as the advances in software and technology, the analysis of pile foundations and especially those loaded laterally remains a challenge to the engineers. This paper reviews the literature regarding the development of the analysis methods through time going all the way back to 1867 and the subgrade reaction method by winkler and reaches today and the current state of the art. The analysis methods are grouped into the subgrade reaction methods, the ultimate limit state methods, the continuum methods and finally the finite element method. The main objective is to present the fundamentals of each method in an effort to make a contribution to the design of pile foundations by providing a reference and a critical discussion to the geotechnical engineers.

Construction and Retrofit Methods of Stone Masonry Structures in Cyprus

Natural stone is a durable construction material which has been used through centuries for various types of structures. These structures are exposed to corrosive and degradation factors such as climate change and pollution, natural ageing, earthquake actions, increasing urbanization and even human negligence, potentially exposing them to irreversible structural damage and loss. Considering the large number of traditional structures and the historic value of a great number of stone masonry structures, the necessity of maintenance, repair, retrofit and restoration of stone masonry structures is imposed. The process which leads to the preservation of such structures consists of three stages: 1) the in-situ and laboratory study of the degree of damage and of the factors which cause the natural damages on the materials of these buildings, 2) the detailed drawing of the layout and the elevations. This stage also includes the selection of the appropriate measures for the maintenance and retrofits according to the special characteristics of the structure and the design of the intervention method, and 3) the execution of all the intervention works. This paper presents a description of various types of natural stones found in Cyprus, the most commonly used construction methods as well as methods for the retrofit of stone masonry structures.

Analysis of Tensegrity Structures with Redundancies, by Implementing a Comprehensive Equilibrium Equations Method with Force Densities

A general approach is presented to analyze tensegrity structures by examining their equilibrium. It belongs to the class of equilibrium equations methods with force densities. The redundancies are treated by employing Castigliano’s second theorem, which gives the additional required equations. The partial derivatives, which appear in the additional equations, are numerically replaced by statically acceptable internal forces which are applied on the structure. For both statically determinate and indeterminate tensegrity structures, the properties of the resulting linear system of equations give an indication about structural stability. This method requires a relatively small number of computations, it is direct (there is no iteration procedure and calculation of auxiliary parameters) and is characterized by its simplicity. It is tested on both 2D and 3D tensegrity structures. Results obtained with the method compare favorably with those obtained by the Dynamic Relaxation Method or the Adaptive Force Density Method.