A practical method for optimum seismic design of friction wall dampers

Friction control systems have been widely used as one of the efficient and cost effective solutions to control structural damage during strong earthquakes. However, the height-wise distribution of slip loads can significantly affect the seismic performance of the strengthened frames. In this study, a practical design methodology is developed for more efficient design of friction wall dampers by performing extensive nonlinear dynamic analyses on 3, 5, 10, 15, and 20-story RC frames subjected to seven spectrum-compatible design earthquakes and five different slip load distribution patterns. The results show that a uniform cumulative distribution can provide considerably higher energy dissipation capacity than the commonly used uniform slip load pattern. It is also proved that for a set of design earthquakes, there is an optimum range for slip loads that is a function of number of stories. Based on the results of this study, an empirical equation is proposed to calculate a more efficient slip load distribution of friction wall dampers for practical applications. The efficiency of the proposed method is demonstrated through several design examples

Strength development of plain concrete compared to concrete with a non-chloride accelerating admixture

Purpose – The purpose of this paper is to show how the investigation into early strength gain of concrete will allow the contractor to speed up the construction process using in situ concrete, which will affect subsequent time and cost savings. If a medium dose of accelerator was found to be effective, the cost/benefit would be substantial as well as being low risk with regard to additive additions in concrete. Design/methodology/approach – Comparative examination of plain concrete, and concrete with a non-chloride accelerator additive was carried out, using the compressive strength to establish strength gain at various time intervals between one and 28 days. The additive dose was less than half of the maximum recommended to avoid the strength loss problems associated with the use of accelerating admixtures due to possible overheating. Findings – The findings showed a significant increase in strength using an accelerating admixture in the early life of the concrete, which may allow a contactor to strike the formwork earlier, due to the use of an admixture, thus speeding up the construction process to produce time/cost savings. Originality/value – The research will assist the designer, contractor and health and safety co-ordinator to strike formwork at the earliest date with greater certainty and therefore reduced risk. By using an accelerator, rather than increasing the cement content to achieve early life strength, this paper displays another way to produce sustainable buildings with a lower carbon footprint. Early life strength provides better freeze/thaw protection and a greater resistance to impact damage and therefore a potential higher quality with lower defects

Parametric Investigation of Traditional Vaulted Roofs in Hot-Arid Climates

In the Mediterranean and North African regions, traditional vaulted roof forms have been widely used due to their significant influence on enhancing thermal indoor conditions. This research parametrically investigates the thermal performance of vaulted roofs, seeking a better understanding of the reciprocal relationship between the solar irradiance received by these roofs and the resulting energy consumption in the hot-arid city of Aswan (23.58oN), Egypt. The methodological procedure is realized through two phases. The annual simulations of solar irradiance and energy consumption are carried out in the first phase, where the quantitative performance of 2,310 different cases are predicted in terms of six vaulted roof forms against eleven key influencing variables. The unsupervised technique of Principal Component Analysis is used in the second phase to reduce the higher dimensionality of the resulting dataset and extract important information from newly established orthogonal principal components. The outcomes of this work aim to provide architects and practitioners with an optimized dataset to use in the design and application of vaulted roof forms and support decision makers addressing the development strategies by providing essential data for setting regulations of newly built environments in harsh hot-arid contexts

Design procedures of reinforced concrete framed buildings in Nepal and its impact on seismic safety

The present paper analyses the design procedure and its impact on seismic safety of the structures. For this, a representative reinforced concrete frame building (WDS) is designed and the results are compared with similar buildings detailed with: i) Current Construction Practices (CCP); ii) the Nepal Building Code (NBC) and iii) the Modified Nepal Building Code (NBC+) recommendations. The seismic performance evaluation is done with global strength, inter-storey drift and displacement of the structures. Likewise, the sensitivity of the structural and geometrical parameters of the RC frame building is studied through nonlinear analysis. The study parameters considered for parametric analysis are column size, beam size, inter-storey height, bay length, bay width, and compressive strength of concrete. The results show that the influence on the structural behaviour, particularly by variation in column size and inter-storey height. Additionally, the influence of the seismic zone factor on reinforcement demand of the structure is studied. The result shows that structures designed for high to medium seismic hazard demands double the reinforcement in beams compared to structures in low seismic zone

Model Code for Energy Conservation in New Building Construction

76 pagesIn response to the recognized lack of existing consensus standards directed to the conservation of energy in building design and operation, the preparation and publication of such a standard was accomplished with the issuance of ASHRAE Standard 90-75 "Energy Conservation in New Building Design", by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., in 1975. This standard addressed itself to recommended practices for energy conservation, using both depletable and non-depletable sources. With a nationally recognized standard now available, consistent and uniform application was determined as necessary. The development of a national model building design regulatory document was accomplished through funding by the United States Department of Energy by those organizations primarily concerned with code development and writing. A model code for energy conservation in building construction has been developed, setting forth the minimum regulations found necessary to mandate such conservation. The code addresses itself to the administration, design criteria, systems elements, controls, service water heating and electrical distribution and use, both for depletable and non-depletable energy sources. The technical provisions of the document are based on ASHRAE 90-75 and it is intended for use by state and local building officials in the implementation of a statewide energy conservation program