节点局部加强钢框架的抗震性能分析

对节点局部加强的抗弯钢框架的抗震性能进行研究,考虑地震和模型误差。根据已有的研究成果,建立局部加强节点模型,模拟3个按现有标准设计的不同高度的建筑。为反映阶段变化,在性能化地震工程方法中采用增量动力分析。在考虑和不考虑模型误差的两种情况下,对多个响应水平下的结构性能进行概率评估。为进行模型误差分析,将能很好反映结构变化的参数数量设为随机变量。使模型变量在平均值附近变化,进行一系列敏感性增量动力分析,并确定多项式响应面。建立节点响应面,并采用蒙特卡罗模拟,可在不同的结构响应水平下进行全概率性能分析。变更预测性能时模型误差对结构单元研究的影响不大。     

Adapting aspects of GBTool 2005—searching for suitability in Taiwan

One of the main areas of activity in the concept of Sustainable Building (SB) is the development of methods and tools used to assess the environmental performance of buildings. GBTool is the software implementation of the Green Building Challenge (GBC) assessment method, which has been under development since 1996 by International Initiative for a Sustainable Built Environment (iiSBE) and participating teams from more than 20 countries. The method also places emphasis on the ability of local users to adjust the system to suit regional technical and cultural issues. This study seeks to explore regional customization of GBTool2005. That is, we will utilize the AHP method to investigate the priority of the so-called “Issues” and “Categories” of the GBTool2005, by compiling and completing an experts’ questionnaire. This questionnaire is aimed at proposing a separate set of feasible weightings for Issues and Categories of GBTool2005 by the AHP method, and to present the “critical” assessment factor for Taiwan.     

First exploratory study on dynamic characteristics of rammed earth buildings

Rammed earth construction is attracting a renewed interest throughout the world thanks to its “green” characteristics in the context of sustainable development. Several studies have been carried out to investigate this material and evaluate its durability along with its mechanical, thermal and earthquake capacities. This paper presents a study on the parameters needed for the seismic design of rammed earth buildings in accordance with current earthquake standards. First, the dynamic parameters of buildings such as natural frequencies and damping ratios-which were necessary to determine the equivalent static seismic force-were identified using in-situ dynamic measurements. Then, these experimental values were compared with the values calculated by empirical formulas suggested in Eurocode 8 to demonstrate that these formulas were applicable for the cases of rammed earth structures. Then, modeling was done to find a simple suitable model for rammed earth structures. Laboratory experiments were developed to measure the Poisson’s ratio which was necessary for the models. The results provided by the shear-beam model were close to that of in-situ experiments, which showed a shearing behavior of rammed earth structures. Elements which influenced the dynamic behavior of this structural type were also discussed. Understanding the dynamic characteristics of rammed earth structures will help engineers in their design of new rammed earth buildings but also in earthquake analyses of existing rammed earth buildings.     

A Monte Carlo based method for the dynamic “fragility analysis” of tall buildings under turbulent wind loading

This paper presents a numerical algorithm for the simulation of the along-wind dynamic response of tall buildings under turbulent winds, using Monte Carlo (MC) integration methods. The proposed MC numerical procedure was used to compute the power spectral density of the buffeting loads, and to derive the statistics of the dynamic response in the presence of uncertainty in the wind loading. The CAARC prototype building was utilized to validate the proposed algorithm. This paper also presents the computation of the structural fragility curves of the CAARC building under extreme winds; preliminary investigations were conducted to assess the applicability of the proposed algorithm to a performance-based assessment.The results of these studies validated the appropriateness of the developed algorithm through comparison to reference values obtained from the literature for the CAARC building. Furthermore, structural “fragility curves” were utilized for a preliminary performance analysis, based on simulated along-wind response serviceability limit states.     

Robust control of civil structures with parametric uncertainties through D‐K iteration

Active control is an alternative method to suppress the civil structural vibration, which is more effective than the passive control or strengthening the structural components. The performance of active control is dependent on the control strategy and the accuracy of the structural model. However, there always exist some uncertainties in the model, such as mass, damping and stiffness uncertainties. This paper presents a robust H_∞ controller design for civil structures with consideration of the parametric uncertainties. The formulation to extract the parametric uncertainties from the structural model matrices is proposed through the linear fractional transformations approach. The robust H_∞ controller design for the civil structures with the parametric uncertainties is achieved through the D‐K iteration method. The linear matrix inequality is then used in the H_∞ optimization procedure of the D‐K iteration. The robustness of the controller is first numerically validated by a four‐story building example and then experimentally corroborated by a shaking table test of a two‐story frame with one active mass damper. The results show that the robust H_∞ controller can consider the parametric uncertainties in the civil structural model and achieve the robust performance. Copyright © 2015 John Wiley & Sons, Ltd.     

Energy performance of traditional bath buildings

This paper presents the results of a recent research effort to collect and analyze data pertaining to traditional bath buildings (“hammams”) in Egypt, Turkey, Morocco, Syria, and Algeria. Thereby, the energy performance of and the thermal comfort conditions in five such buildings were studied. Moreover, empirically calibrated building performance simulation models of a number of objects were generated in order to predict the consequences of alternative thermal retrofit measures. The results provide the opportunity for an objective assessment of the actual energy and indoor environmental performance of these buildings.     

Study of a semi-rigid steel braced building damaged in the Bam earthquake

A steel frame building with an X-bracing system, infill panels in both directions and “Khorjini” connections damaged in the Bam earthquake was studied using nonlinear dynamic analysis. To model the nonlinear force-deformation characteristics of columns, infill panels and braces, the specifications given in FEMA-356 were used, whereas for the Khorjini connections experimental results demonstrated these specifications.The comparison criterion for damage was life safety performance. The results show good correspondence of the building’s overall behavior in a story drift event. The extent of damage to columns and infill panels is in excellent correlation with the real damaged structure.It was also shown that most of the energy was absorbed by the infill panels, and for this complex system the infill panels played a crucial role in preventing the structure from collapse.     

Effect of parametric uncertainties on wind excited structural response

This paper addresses the influence of parametric uncertainties on the wind excited response of structures. Based on the available experimental data from both laboratory and field studies, the variability in the parameters related to the wind environment and meterological data, kinematics of wind flow field, wind-structure interaction and structural properties is assessed. The random variability in the parameter space is propagated to ascertain its influence on the structural response statistics utilizing a Monte Carlo simulation technique. By means of an example, the influence of parametric uncertainties on the dynamic response of a tall reinforced concrete chimney is presented. The analysis of simulated data suggests a need for further improvement in the modeling of wind-structure interaction, prediction of natural frequencies and damping, and a reduction in the variability of extreme wind estimates.     

Seismic performance of the Accordion-Web RBS connection

A new type of Reduced Beam Section (RBS) connection, “Accordion Web RBS (AW-RBS)”, is presented in this research. RBS connections are commonly known as connections with reduced flange width within a limited area near the column face. However, the AW-RBS decreases the web contribution in moment strength and a reduced section is developed in the beam. In an AW-RBS, the flat web is replaced by corrugated plates (L-shape folded plates, used here) at the expected location of the beam’s plastic hinge. While the corrugated web has adequate shear strength, its provided moment strength and flexural stiffness are negligible. Two relatively identical specimens including AW-RBS connections have been tested under cyclic loading. Both specimens provide at least 8% story drift, without any significant strength loss, which is more than current requirements for qualifying connections in special moment frames. The accordion effect of the corrugated web and the cyclic performance of the connection are verified by analytical results. According to the analytical and experimental results, the inelastic rotations of the connection are mostly provided by reliable and ductile rotation at the reduced region rather than in the connection plates or panel zone.     

A simplified method for collapse capacity assessment of moment-resisting frame and shear wall structural systems

A simplified methodology for predicting the median and dispersion of collapse capacity of moment-resisting frame and shear wall structural systems subjected to seismic excitations is proposed. The method is based on nonlinear static (pushover) analysis. Simple mathematical models denoted as “generic structures” are utilized to model moment-resisting frames and shear walls. After examining a wide range of structural parameters of the generic structures, a comprehensive database of collapse fragilities and pushover curves (using ASCE 7-05 lateral load pattern) are generated. Based on the obtained pushover curves, closed-form equations for estimation of median and dispersion of building collapse fragility curves are developed using multivariate regression analysis. Comparing the estimates of the median collapse capacity calculated from the closed-form equations with the actual collapse capacities determined from nonlinear response-history analysis indicates that the simplified methodology is reliable. The effectiveness of this methodology for predicting the median collapse capacity of frame and wall structures is further demonstrated with two case studies of structural systems designed based on current seismic provisions.     

Thermal comfort and workplace occupant satisfaction—Results of field studies in German low energy office buildings

The issues of comfort and workspace quality in buildings have gained much importance with the European “Energy Performance of Buildings Directive” of 2001. New energy efficient building concepts and technologies require a revision of comfort standards, which were developed for air-conditioned buildings only. Particularly, the question of recommendable upper indoor temperature limits needs further investigation. In addition, a broader approach to occupant satisfaction in buildings is necessary with respect to overall building performance.     

Relating Sick Building Symptoms to Environmental Conditions and Worker Characteristics

Abstract Recent concern has centered on “sick buildings” in which there has been an unusually high percentage of health complaints by the building's occupants. Typically, these symptoms are thought to be tied to indoor air quality characteristics, such as high levels of respirable particles or volatiles, thermal conditions, etc. In addition, recent studies have drawn connections between “sick building syndrome” (SBS) symptoms and non-environmental variables, i.e., personal and occupational factors. This paper presents a brief review of a study by Hedge et al. (1995) and additional analyses of their data. In a study of 27 air-conditioned office buildings, Hedge et al. measured nine indoor environmental conditions at various locations within each building and concurrently questioned workers on sixteen SBS symptoms and a number of other personal factors. The additional analyses presented in this paper attempt to draw formal statistical connections between SBS symptoms and both personal worker characteristics and indoor air pollutants simultaneously. The analyses were based on symptom severity response variables whic include information not only on the frequency with which an individual experienced a symptom, but also on how much the symptom disrupted the individual's work. Results from sixteen linear mixed effects models indicate that significant predictors are primarily personal and occupational in nature rather than environmental. For a number of the symptoms, additional variability attributable to buildings exists. However, any physical explanation of this variability remains unclear.     

Energy retrofit of historical buildings: theoretical and experimental investigations for the modelling of reliable performance scenarios

The paper suggests a multi-criteria approach for the energy refurbishment of historical buildings, proposing methodologies for the performance analysis, coupling several experimental and numerical studies. The target consisted in a rigorous evaluation procedure, in order to guarantee the necessary reliability of a numerical model of the system “building envelope/technical plants”, on which testing the technical and economical convenience of energy retrofit solutions.The paper collects the long work carried out by several Institutions during the last years, on Building “Palazzo dell’Aquila Bosco-Lucarelli”, a historical building located in Benevento (Southern Italy), currently analyzed in order to define the technical adoption of possible improving actions.The carried out studies, beyond the proposition of an operational methodology, are aimed to evidence a best-practice specified for the Italian territorial context, which has several historical buildings needing restoration.Carefully applied investigations, based on various methodologies and through several instrumentations, allowed the definition of a numerical model correspondent to the real building, defined also comparing the results with the historical requests of gas and electricity. Moreover, dynamic energy simulations tested the effectiveness, singularly and coupled, of several solutions for the building energy optimization. A significant potentiality of energy and economic optimization has been demonstrated.     

钢框架螺栓连接迟滞力学信息模型

强震作用下,钢和组合框架梁-柱螺栓连接节点的性能对其结构响应有着显著影响。其滞后响应表现为高度地无弹性特性以及刚度、强度和延展性的不断变化,从而影响结构的抗力。因此,为准确进行地震评估和设计,精确的螺栓连接滞回模型必不可少。提出了一种新的混合建模方法,可用于描述强震作用下框架螺栓连接节点复杂的滞回性能。该方法假定并非连接响应的所有特征均服从力学模型,因此,以信息为基础的替代方案是可行的。传统力学模型通过以信息为基础的模型单元对复合力学信息模型(HMIM)进行补充。信息单元了代表力学模型的各个方面。通过板件的翼缘连接展示了HMIM的效果,该连接表现出捏缩迟滞特性。     

Improving the energy performance of the built environment: The potential of virtual collaborative life cycle tools

Advances in information and communication technologies [ICTs] offer the opportunity to improve the way energy profiling tools and techniques are used to measure and inform the energy performance of buildings throughout their life cycle. The exploitation of this potential is one of the goals of a current EU FP7 funded project, entitled “IntUBE — Intelligent Use of Buildings' Energy Information”. The overall aim of the project is to improve the energy performance of new and existing buildings via the intelligent use of buildings' energy information. The main aim the energy profiling research being conducted as part of the IntUBE project is to contribute to the development of virtual collaborative ‘life cycle’ building tools to support energy efficient building design, operation and retrofit. In order to illustrate how this may be achieved this paper defines the functions of energy simulations within the IntUBE system, outlines the systems architecture necessary to those functions and presents a case study illustrating some of the functionality under development.     

Project leaders as boundary spanners: Relational antecedents and performance outcomes

Research has shown that NPD project leaders should engage in boundary-spanning activities. The present study tested the impact of four boundary-spanning activities on NPD project performance and analyzed the antecedents of these activities. We hypothesized that NPD project leaders' abilities to perform these activities depend on the characteristics of their personal networks — structural holes, strength of ties, vertical and horizontal bridging ties. A Partial Least Squares test on 73 NPD projects showed that (a) “obtaining political support” and “scanning for ideas” are the boundary activities with the greatest impact on performance, (b) project leaders with strong ties in their network are more effective at these activities, (c) project leaders with structural holes in their networks are more effective in another boundary activity, “protecting the team”, although this activity does not affect NPD outcomes. These results represent an important contribution to understanding how team leaders contribute to project performance.     

Cost-benefit evaluation of self-centring concentrically braced frames considering uncertainties

Self-centring concentrically braced frame (SC-CBF) systems have been developed to reduce post-earthquake damages in braced frames. However, due to special details required by the SC-CBF system, the construction cost of an SC-CBF is expected to be higher than that of a conventional CBF. In this study, the seismic performance and economic effectiveness of two prototype buildings utilising SC-CBFs are assessed and compared with buildings utilising conventional CBFs by evaluating the annual probabilities of exceeding various damage levels, expected annual losses, life cycle costs (under seismic hazard) and economic benefit of using SC-CBFs considering prevailing uncertainties. The results of this study show that the SC-CBF buildings have lower drift-related losses but higher acceleration-related losses. The SC-CBF is found to be beneficial for the 6-storey configuration, but not for the 10-storey configuration. For the 6-storey buildings studied here, if the construction cost of the SC-CBF is assumed to be twice that of the CBF, the pay-off time is expected to be 12 to 21 years, with a probability of 68%, considering the uncertainties in the demand, capacity, loss parameters and initial construction costs. Finally, appropriate probabilistic engineering demand parameter model formulation is critical for generating accurate loss analysis results.     

Uncertainty analysis in building performance simulation for design support

Building performance simulation (BPS) has the potential to provide relevant design information by indicating directions for design solutions. A major challenge in simulation tools is how to deal with difficulties through large variety of parameters and complexity of factors such as non-linearity, discreteness, and uncertainty.The purpose of uncertainty and sensitivity analysis can be described as identifying uncertainties in input and output of a system or simulation tool [1], [2] and [3].In practice uncertainty and sensitivity analysis have many additional benefits including: (1) With the help of parameter screening it enables the simplification of a model [4]. (2) It allows the analysis of the robustness of a model [5]. (3) It makes aware of unexpected sensitivities that may lead to errors and/or wrong specifications (quality assurance) [6], [7], [8], [9] and [10]. (4) By changing the input of the parameters and showing the effect on the outcome of a model, it provides a “what-if analysis” (decision support). [11].In this paper a case study is performed based on an office building with respect to various building performance parameters. Uncertainty analysis (UA) is carried out and implications for the results considering energy consumption and thermal comfort are demonstrated and elaborated. The added value and usefulness of the integration of UA in BPS is shown.     

Composite (steel-concrete) highway bridge fatigue assessment

Steel and composite highway bridges are currently subjected to dynamic actions with variable magnitudes due to the action of vehicles crossing on the deck pavement. These dynamic actions can generate the nucleation of fractures or even their propagation in the structures. Depending on the magnitude and intensity, these adverse effects can compromise the structural system response and the reliability which may also lead to a reduction of the expected bridge service life. A composite (steel-concrete) bridge with a 12.50 m roadway width and 0.23 m concrete deck thickness, spanning 40.0 m by 13.5 m was investigated in this work. The computational model, developed for the composite bridge dynamic analysis, adopted the usual mesh refinement techniques present in finite element method simulations, and was implemented in the ANSYS program. The proposed analysis methodology and the procedures presented in the design codes were initially assessed to evaluate the bridge fatigue response in terms of its structural service life. The stress cycle counting techniques and the cumulative damage rule application had been analyzed through S-N curves, based on an extensive revision of steel and composite bridges’ service life and theoretical fatigue aspects in steel structures. The investigation also considered the recommended procedures used for the steel and composite structures’ main codes. The main conclusions of this paper focused on alerting structural engineers to the possible distortions, associated with the steel and composite bridges’ service life when subjected to vehicles’ dynamic actions.