On the effect of large deflection on nonlinear behavior of an eccentric bracing system

In this article, a particular off‐center bracing system is introduced. In this system, the tensile diagonal strut is not straight. When the load is applied, the original geometry changes and thus causes the system to harden. Based on this behavior, a step‐by‐step analytical method is developed. Using this method, a Geometrically Nonlinear Analysis Program (GNAP) is designed to analyze the elastic force–displacement relation. Extension of this program to dynamic analysis led to a Dynamic Nonlinear Analysis Program (DNAP). The object of this article is to show that such bracing systems will lead to less seismic force on such structures compared to classic concentric bracing systems. On the other hand, it will be shown that the bracing system causes semi‐uncoupling of structure, and that the probable excursions in the nonlinear range during severe earthquakes will not cause significant deterioration in its strength and stiffness. Copyright © 2007 John Wiley & Sons, Ltd.     

Patterns of exits from housing in a homelessness system of care: the case of Calgary,Alberta

Public officials around the world seek to target subsidized housing as purposely and efficiently as possible. With limited availability of subsidized housing, it is helpful to know which household types require specific types of housing support and for how long. With this in mind, we undertake survival analysis and hazard models on clients placed into housing funded by the Calgary Homeless Foundation (CHF) to characterize patterns of exit from Calgary’s homeless system of care. To do this, we use data from Calgary’s Homelessness Management Information System from 1 April 2012 until 31 March 2015. We find singles without dependents to require housing support for the longest period of time, while families require the support for the least amount of time. One important finding is that women require housing support for longer periods of time than men (even though we control for employment and income).     

A recursive algorithm for generating the equations of motion of spatial mechanical systems with application to the five-point suspension

In this paper, a recursive formulation for generating the equations of motion of spatial mechanical systems is presented. The rigid bodies are replaced by a dynamically equivalent constrained system of particles which avoids introducing any rotational coordinates. For the open-chain system, the equations of motion are generated recursively along the serial chains using the concepts of linear and angular momenta. Closed-chain systems are transformed to open-chain systems by cutting suitable kinematic joints and introducing cut-joint constraints. The formulation is used to carry out the dynamic analysis of multi-link five-point suspension. The results of the simulation demonstrate the generality and simplicity of the proposed dynamic formulation.     

Optimum depth of grout curtain around pumped storage power cavern based on geological conditions

The main objective of this work was to study the design rationale for the optimum grout curtain around the power cavern of the Rudbar Lorestan pumped storage power plant. This grout curtain will prevent water inflow into the power cavern after Rudbar Dam is impounded. This study was based on a combination of geotechnical investigations, geological investigations, and numerical modeling. The power cavern is located in the Dalan Formation, which consists of limestones and dolomite limestones. Geological features such as faults and major joints in limestones as well as the close proximity of the power cavern to the downstream reservoir increase the hazard associated with water inflow from the reservoir into the power cavern. Because of this close proximity, accurately estimating the water inflow into the cavern is an essential task. Three exploratory boreholes were drilled near the power cavern, and permeability tests (Lugeon tests) were conducted in all boreholes. Records at the boreholes were employed as the main source of data for seepage calculations, and it was determined that the permeability of the limestones is approximately 1.25 × 10^?3 m/s. This study used a finite element model to estimate groundwater inflow into the power cavern after the downstream reservoir is impounded. Results show that without a grout curtain, water would seep into the cavern at a rate of about 0.8–1 m³/s, which would make it difficult to operate the power plant. Accounting for geological conditions such as the Rudbar Fault and fractured limestones, as well as the limitations on construction, a grout curtain was designed. The design calls for a curtain that is about 50 m from the power cavern and extends from 1,735 m.a.s.l. to 10 m below the cavern. Modeling the effect of the grout curtain around the cavern with the finite element method showed that the seepage would decrease to a low rate of 0.1 m³/s with the installation of the curtain.     

Use of multisensor and multitemporal geospatial datasets to extract the foundation characteristics of a large building: a case study

Bulletin of Engineering Geology and the Environment - The assessment of the ground conditions for large buildings is important because the results are sensitive to the ground conditions, especially...     

Rapid determination of soil unconfined compressive strength using reflectance spectroscopy

Bulletin of Engineering Geology and the Environment - Understanding the physical and especially mechanical properties of forest soils is very important in forest engineering operations including...     

3D experimental and numerical analysis of wind flow around domed-roof buildings with open and closed apertures

This paper presents experimental and numerical study of airflow distribution around a reduced-scale model of a common type of domed-roof building. Measurements are performed in an open loop wind tunnel. A new modified Counihan scheme is developed for constructing a part-depth atmospheric boundary layer (ABL). Measured quantities include: wind velocity profile, turbulence intensity and airflow pattern around the building. To conduct the experiments, a 1:54 scale model of a real domed-roof building with six windows and an aperture on the roof is fabricated and placed in the test section of the wind tunnel. In addition, using a numerical modeling, turbulent airflow around such scale model in the wind tunnel is simulated and airflow field inside and outside the model as well as ventilating discharge coefficient are computed. It is illustrated that, airflow around this type of building contains complex adjacent recirculation flows. The building with open apertures has acceptable discharge coefficient for ventilation, which can be a factor to ensure comfort condition for residents as well as complying with energy-saving considerations.     

加劲肋对焊缝区域应变模式的影响

通过试验和数值分析对工字形梁和箱形柱焊接连接的性能进行探讨,以获得加劲肋和柱翼缘厚度对连接耗能性能的影响。采用有限元法对试验构件进行了建模和分析,并将结果与全尺试验对比。考虑了各类加劲肋的影响,包括:柱加劲肋、侧向加劲肋、翼缘顶部和底部加劲肋。评测了各种加劲肋在塑性变形控制和连接耗能性能方面的贡献。     

Study of the antiferromagnetic phase in Sm(Mn1−xCrx)2Ge2

Magnetic and thermal expansion measurements have been carried out on the polycrystalline Sm(Mn_1−xCr_x)₂Ge₂ samples to see how the antiferromagnetie (AFMII) region in SmMn₂Ge₂ is affected by Cr substitution. It is found that the antiferromagnetic region disappears for samples with less than 2 at.% of Cr. Sharp changes in the thermal expansivity (Δl/l) at FMI–AFMII and AFMII–FMII transitions are observed, indicating first order transitions. The decrease in relative thermal expansivity at the two transitions with the increase of Cr concentration is related to the decrease in the stability and the temperature-range of the AFMII phase observed in magnetization measurements. A spin reorientation transition (T_SR) has been observed for x=0, at 148 K. It is found that the T_SR increases with the increase of Cr concentration. A magnetic phase diagram as a function of Cr concentration in Sm(Mn_1−xCr_x)₂Ge₂ has been constructed.     

Design eco-drivers

Interest in ecological design issues has increased enormously over the past few decades and ecological problems are perceived to be on the increase. This paper seeks to investigate the relative importance of the design eco-drivers contributing to ecological building design (EBD) success in the UK. A large number of eco-drivers have been extracted from literature and current design practices. To compare views from architects, data were collected from a statistically significant number of practising architects in the area of sustainable design. The data collected represent the views and ambitions of surveyed architects and not necessarily their current design practices. Ranking techniques are utilised to identify the connotation of eco-design indicators. Based on this analysis, the most important eco-design drivers are extracted. From the results of the overall ranking 'energy, efficiency, energy consumption, energy-eco-efficiency and environmentally adapted technology', eco-drivers are ranked as the most important factors amongst others. This indicates that the surveyed architects strongly perceive ecological design as being driven by energy aspects of building assets. This suggests that these findings are more sensitive to respondents' perception rather than to actual design practices. The selected eco-indicators could be used to assist designers in carrying out ecological design contextual synthesis as well as developing ecological design strategies.