Integrated design of Smart Structures

Much of structural control research and applications in civil engineering have been concerned with structures equipped with passive, hybrid, or active control devices in order to enhance structural performance under extraordinary loads. In most cases, the structure and the control system are individually designed and optimized. On the other hand, an exciting consequence of structural control research is that it also opens the door to new possibilities in structural forms and configurations, such as lighter buildings or bridges with longer spans without compromising on structural performance. Moreover, this can only be achieved through integrated design of structures with control elements as an integral part. This paper addresses the integrated design of structures with imbedded control systems and devices. Simultaneous optimization of such controlled structures is considered, showing that new structural forms and configurations can be achieved through integrated design. © 2008 Trans Tech Publications, Switzerlan

Narrow-Band Excitation of Hysteretic Systems

The stationary response of smooth and bilinear hysteretic systems to narrow-band random excitations is investigated by using the quasistatic method and digital simulation. It is shown that the response is qualitatively different in different ranges of values of the ratio of the excitation central frequency to the natural frequency of the system. In the resonant zone, the response is essentially non-Gaussian. For bilinear hysteretic systems with strong yielding, stochastic jumps may occur for a range of values of the ratio between nonresonant and resonant zones

Integrated Design of Smart Structures

Much of structural control research and applications in civil engineering have been concerned with structures equipped with passive, hybrid, or active control devices in order to enhance structural performance under extraordinary loads. In most cases, the structure and the control system are individually designed and optimized. On the other hand, an exciting consequence of structural control research is that it also opens the door to new possibilities in structural forms and configurations, such as lighter buildings or bridges with longer spans without compromising on structural performance. Moreover, this can only be achieved through integrated design of structures with control elements as an integral part. This paper addresses the integrated design of structures with imbedded control systems and devices. Simultaneous optimization of such controlled structures is considered, showing that new structural forms and configurations can be achieved through integrated desig

Integrated design of inelastic controlled structural systems

This paper addresses the integrated design of civil engineering inelastic structures with embedded control systems and devices. Simultaneous optimization of such controlled structures is considered, showing that new structural forms and configurations can be achieved through integrated design. An optimization procedure for controlled structural systems is developed. The optimal design of (i) an SDOF steel portal frame and (ii) an 8-DOF shear-type structure is used as examples to illustrate the feasibility of the proposed approach, which reduces the structural weight of the buildings by incorporating active control elements while preserving the same performance objectives. The numerical results illustrated by these two examples show practical applicability, especially for the case of high-rise buildings

The influence of maternal weight correction formulas in Asian Down syndrome screening using alpha-fetoprotein and free beta-human chorionic gonadotropin

Objective: To investigate the relationship between maternal weight and serum alpha-fetoprotein (AFP) and free beta-human chorionic gonadotropin (beta-hCG) levels and to determine the methodology of correction formulas for influencing the results of Down syndrome screening in an Asian population. Methods: 8.194 normal singleton pregnancies without any congenital anomalies were screened using AFP and free beta-hCG between 14 and 22 weeks of gestation. Down syndrome risk was calculated by bivariate gaussian algorithm that combined information from the two biochemical measurements and maternal age. The all points regression method and median regression method were used to approach the study cases. Linear and quadratic regression correction formulas for AFP and free beta-hCG, either in analyte multiples of the median (MoM) or log analyte MoM, against maternal weight have been proposed in this study. Results: The mean maternal weight is 54.95 +/- 7.36 kg in Taiwanese pregnant women during the second trimester. There is a distinctly inverse relationship between maternal weight and serum marker levels. The log quadratic regression correction formula was the most satisfactory equation fit to the distribution of both AFP and free beta-hCG levels with a wide weight range, Routine weight correction may have the small benefit of reducing the screen-positive rate 0.36% at the risk cut-off level of 1:270. Conclusions: Maternal weight may affect the AFP and foe beta-hCG levels. Although there is no discernible effect in maternal weight adjustment, it is worth making weight corrections for serum marker levels in order to reduce individual variance

Integrated Design of Smart Structures

Much of structural control research and applications in civil engineering have been concerned with structures equipped with passive, hybrid, or active control devices in order to enhance structural performance under extraordinary loads. In most cases, the structure and the control system are individually designed and optimized. On the other hand, an exciting consequence of structural control research is that it also opens the door to new possibilities in structural forms and configurations, such as lighter buildings or bridges with longer spans without compromising on structural performance. Moreover, this can only be achieved through integrated design of structures with control elements as an integral part. This paper addresses the integrated design of structures with imbedded control systems and devices. Simultaneous optimization of such controlled structures is considered, showing that new structural forms and configurations can be achieved through integrated design