Simplified procedure for seismic analysis of asymmetric buildings

A simplified procedure, which is a modification of the shear beam model, has been developed and applied to treat the seismic analysis of asymmetric buildings. This three dimensional procedure accounts for torsional coupling and the bending rotations at beam–column junctions and it can be used with a personal computer to give fast and reasonably accurate results, which compare well with those from comprehensive finite element analysis. This procedure will therefore be useful for preliminary seismic analysis and design of buildings.     

Deterministic and stochastic seismic analysis of buildings with uncertain-but-bounded mass distribution

The actual and the computed seismic response of buildings are in general different due to the unavoidable uncertainties involved in the definition of the mass and stiffness distributions as well as in the estimation of the ground motion spatial variability. The discrepancies are accounted for by building codes through the so-called accidental eccentricity, which defines the bounds of the actual position of the centre of mass for each floor. Therefore, the seismic analysis problem is posed as the finding of the response of a structural system with uncertain-but-bounded parameters forced by deterministic or stochastic loads. In this paper, in the framework of the interval perturbation method, a procedure for determining upper and lower bounds of the dynamic response of structures with uncertain-but-bounded mass distribution vibrating under either deterministic or stochastic input is proposed. The procedure requires the definition of a unique structural model so reducing the number of analyses to be performed. Moreover, by the proposed approach all the possible permutations are implicitly considered so to include the worst condition. Numerical results showed a very good accuracy of the proposed procedure for all the cases analyzed.     

Multiple-support seismic analysis of large structures

The effect of the spatial variation of earthquake ground motion on the dynamic response of multiple-support structures may be important. The relative performance of two simple analytical methods to model multiple-support seismic analysis of large structures is investigated. These are the relative motion method (RMM), which divides the structural response into a dynamic response component and a pseudo-static response component, and the large mass method (LMM), which attributes fictitious large mass values at each driven nodal degree of freedom (DOF) to obtain the total response of the structure. The seismic response of a four-span bridge using the traveling wave assumption is used to illustrate the practical application of the methods. It is found that the LMM is able to yield results that are almost identical to those of the RMM using large mass values equal to approximately 10⁷ times the total mass of the bridge. Parametric analyses where the travel wave speed is systematically varied show that the structural response tends to increase as the wave velocity decreases and can become significantly larger than the response obtained from synchronous excitation.     

Analysis for P−Δ effects in seismic response of buildings

A matrix formulation to account for P?Δ effects in computer seismic analysis of multistory buildings is presented. The method employs a linear solution approach requiring no iteration and can be used for static or dynamic elastic analyses. Amplified P?Δ effects resulting from inelastic displacement levels which may occur during a major earthquake can be accounted for in an approximate manner. The method has been implemented in a computer program and sample seismic analyses of a 31-story building are presented. Observations on the appropriate use and interpretation of analyses are made.     

Experience of automation failures in training: effects on trust,automation bias,complacency and performance

This work examined the effects of operators’ exposure to various types of automation failures in training. Forty-five participants were trained for 3.5 h on a simulated process control environment. During training, participants either experienced a fully reliable, automatic fault repair facility (i.e. faults detected and correctly diagnosed), a misdiagnosis-prone one (i.e. faults detected but not correctly diagnosed) or a miss-prone one (i.e. faults not detected). One week after training, participants were tested for 3?h, experiencing two types of automation failures (misdiagnosis, miss). The results showed that automation bias was very high when operators trained on miss-prone automation encountered a failure of the diagnostic system. Operator errors resulting from automation bias were much higher when automation misdiagnosed a fault than when it missed one. Differences in trust levels that were instilled by the different training experiences disappeared during the testing session.

Practitioner Summary: The experience of automation failures during training has some consequences. A greater potential for operator errors may be expected when an automatic system failed to diagnose a fault than when it failed to detect one.     

Robust seismic design optimization of steel structures

Stochastic performance measures can be taken into account, in structural optimization, using two distinct formulations: robust design optimization (RDO) and reliability-based design optimization (RBDO). According to a RDO formulation, it is desired to obtain solutions insensitive to the uncontrollable parameter variation. In the present study, the solution of a structural robust design problem formulated as a two-objective optimization problem is addressed, where cross-sectional dimensions, material properties and earthquake loading are considered as random variables. Additionally, a two-objective deterministic-based optimization (DBO) problem is also considered. In particular, the DBO and RDO formulations are employed for assessing the Greek national seismic design code for steel structural buildings with respect to the behavioral factor considered. The limit-state-dependent cost is used as a measure of assessment. The stochastic finite element problem is solved using the Monte Carlo Simulation method, while a modified NSGA-II algorithm is employed for solving the two-objective optimization problem.     

自动引导车系统的设计与仿真

在AGV车体结构初步设计的基础上,运用运动学和动力学理论,给出了车体的动力学模型。提出了通过运动误差方程式导出自动引导车的状态空间模型,根据状态空间表示式来设计路径追踪调节器,应用当今世界上应用最为广泛的计算工具MatIab中的SIMULINK对非线性部分进行图形化建模,并对整个导引系统在各种情况下进行了仿真与分析,修正了控制器的控制参数,通过仿真证明此种调节器的使用可以消除轨迹的误差,使自动引导车具有准确跟踪路径的能力。     

The automation of routine calculations and graphing for alkaline filter elution analysis on a computer-controlled liquid scintillation analyzer

The data calculations and graphing functions for the widely used alkaline filter elution technique have been completely automated. This saves considerable time and increases both efficiency and accuracy by eliminating human error. The automation was accomplished utilizing Lotus 1-2-3 and Lotus Graphwriter II on a Packard Tri-Carb 1900CA liquid scintillation analyzer containing a built-in pico-XTE computer. A batch file is used to control the overall execution of the process. It copies the data stored by the 1900CA into the Lotus subdirectory and invokes Lotus 1-2-3. A Lotus macro automatically imports the data file, performs the calculations, and prints the results. Graphwriter II is then invoked by the batch file and the charts are composed and graphed. Finally, the instrument operating software for the 1900CA is reentered and sample analysis can be resumed for any unanalyzed samples.     

Experimental study on seismic characteristics of typical mortisetenon joints of Chinese southern traditional timber frame buildings

The seismic characteristics of four typical mortise-tenon joints of Chinese southern traditional timber frame buildings were researched,including Yanwei mortise-tenon joint(including dropping Yanwei mortise-tenon joint),Shizigutou mortise-tenon joint,Ban mortise-tenon joint and Mantou mortise-tenon joint.Experiments on thirteen specimens were carried out.Failure modes,hysteresis curves,skeleton curves and rotational stiffness were studied.The results provided a theoretical basis for seismic research,protect...     

Simulation of the earthquake-induced pounding of seismically isolated buildings

Seismic isolation can significantly reduce the induced seismic loads to a relatively stiff building by inserting flexibility at its base to avoid resonance with the predominant frequencies of common earthquakes. Sometimes the width of the provided seismic gap to facilitate the large relative displacements at the isolation level of a seismically isolated building is limited. Hence, there is a possibility of poundings of the building with adjacent structures during strong earthquakes. This work investigates, through numerical simulations using a specially developed software, how potential poundings of seismically isolated buildings with adjacent structures affects the effectiveness of seismic isolation.     

Nonlinear seismic response evaluation of tunnel form building structures

The occurrences of (M_w=7.4) Kocaeli and (M_w=7.1) Duzce earthquakes in Turkey in 1999 once again demonstrate the nondamaged and high performance conditions of RC shear wall dominant structures commonly built by using the tunnel form technique. This study presents their seismic performance evaluation based on the nonlinear pushover analyses of two case studies. The contribution of transverse walls and slab-wall interaction during the 3D action, the effects of 3D and 2D modeling on the capacity-demand relation, as well as diaphragm flexibility, torsion and damping effects were investigated. An effort was spent to develop a shell element having closing-opening and rotating crack capabilities. This study shows that the applied methodology has a considerable significance for predicting the actual capacity, failure mechanism, and evaluation of the seismic response of tunnel form buildings.     

Topology optimization for the seismic design of truss-like structures

A practical optimization method is applied to design nonlinear truss-like structures subjected to seismic excitation. To achieve minimum weight design, inefficient material is gradually shifted from strong parts to weak parts of a structure until a state of uniform deformation prevails. By considering different truss structures, effects of seismic excitation, target ductility and buckling of the compression members on optimum topology are investigated. It is shown that the proposed method could lead to 60% less structural weight compared to optimization methods based on elastic behavior and equivalent static loads, and is efficient at controlling performance parameters under a design earthquake.     

Stochastic optimum design criterion for linear damper devices for seismic protection of buildings

This paper concerns a new approach for the reliability-based optimum design of linear multistory frames seismically protected by viscous dampers. A deterministic objective function, defined as the total added damping, is minimized, while stochastic restraints impose a limit to system failure probability. This latter is here related to a maximum interstory drift crossing over a given value, which is associated with damage control requirements. System failure probability is evaluated by means of the covariance analysis of a frame subject to a seismic load represented by a nonstationary modulated Kanai–Tajimi stochastic process. Numerical examples are developed, concerning a plane-shear-type frame with three floors equipped with viscous damper devices. Two different possible design solutions are performed, considering different earthquake intensities: more in detail, the first adds constant damping at each story, while the second considers a variable added damping distribution.     

A non-linear response history model for the seismic analysis of high-rise framed buildings

A materially non-linear plane-frame model is presented that is capable of analysing high-rise buildings subjected to earthquake forces. The model represents each storey of the building by an assembly of vertical and horizontal beam elements The model introduces yield hinges with ideal plastic properties in a regular plane frame. The displacements are described by the translation (sway) of each floor and the rotation of all beam–column intersections. The mass is only associated with the translations, and thus the analysis can be carried out as a static condensation of the rotations, combined with integration of the dynamic equations for the translations. The dynamic integration is here carried out by use of the Runge–Kutta scheme. This approach allows a building to be modelled by m(n + 2) degrees of freedom (where m is the number of storeys and n is the number of bays). The rank of the condensed stiffness matrix is only m. Its construction, which requires the inversion of the rotational, rank m(n + 1), stiffness matrix, is required only at time-steps where the pattern of yielding has altered from the previous time-step. This model is particularly attractive for non-linear response history analysis of high-rise buildings as it is efficient, allows each storey to have multiple redundancies, and each connection to be modelled with any suitable moment–rotation relationship.Three verification examples are presented and the results from static push-over analysis are compared with time–history results from the simplified model. The results verify that the model is capable of performing non-linear response history analysis on regular high rise buildings.     

The effects of CIM on work structures

The present communication structures of many organizations are governed by extensive manual information transfer, long processing times and receptive recording of data. The introduction of computer-integrated manufacturing (CIM) has the aim of integrating administrative data in manufacturing data, that is to say, the operational EDP-systems of all company sections will be-as far as possible-cross-linked. Existing data can be used by all departments of the company for administrative operations, due the cross-linkage of data transfer. In this way, recording and processing errors will be avoided or minimized. Transition from information processing to professional (expert) systems requires new and more efficient forms of an employee-oriented work organization.     

Possibilities and comparison of structural component models for the seismic assessment of modern unreinforced masonry buildings

This paper addresses the possibilities of structural component models for the seismic assessment of masonry buildings using pushover analysis. The ultimate goal is to allow efficient design of new unreinforced masonry buildings in seismic areas. Different modelling strategies are presented and the implementation of a simple design tool based on structural component models is described in detail. The different approaches are applied to a two-storey building with regular plan and elevation, allowing for a comparison between them. The results indicate that macro-modelling using structural component models and pushover analysis are adequate approaches for the seismic assessment and design of unreinforced masonry buildings, as the tools require very low computational resources, allow easy interpretation of results and provide satisfactory accuracy.     

Recognition of thin, flat microelectromechanical structures for automation of the assembly process

Visual recognition of microelectromechanical parts is necessary for automation of the assembly process. The visual recognition system that we have developed is based partly on neural networks and partly on digital image-processing techniques. The system takes grey-level microscope images and produces recognition code as the output as well as information about micropart position. The recognition procedure is not sensitive to micropart position. This is ensured by preprocessing based on calculation of the image moment properties. For the recognition, a supervised feedforward neural network is utilized. A combination of standard backpropagation and resilient propagation is chosen for learning the network. The performance of the system is tested on recognition of the parts of a microvalve system. The results are satisfactory with respect to recognition accuracy and recognition time.