摘要:

AbstractThis project was conducted to investigate the breakage and fallout behaviour of various types of architectural glass elements in a dry‐glazed curtain wall system under in‐plane and out‐of‐plane dynamic motions. The project was a follow‐up to an earlier project that focused exclusively on in‐plane dynamic racking performance of curtain wall glass elements. The recent data indicated that adding out‐of‐plane motions caused significantly higher amounts of glass breakage and subsequent glass fallout in most glass types that were found during the in‐plane tests to be prone to glass fallout. Specifically, 1/4 in (6 mm) annealed monolithic glass, 1/4 in annealed monolithic glass with a 0·004 in (0·10 mm) PET film (not anchored to the mullions), and 7/16 in (11 mm) fully tempered laminated glass exhibited comparable or higher fallout rates than the already substantial fallout rates that were observed during the in‐plane only racking tests. Unanchored window film was found to be ineffective in resisting post‐breakage glass fallout under dynamic racking motions. In contrast, 1/4 in (6 mm) annealed laminated glass and 7/16 in (11 mm) heat‐strengthened laminated glass exhibited no glass fallout during the out‐of‐plane tests, just as they exhibited no fallout during the in‐plane tests. Out‐of‐plane test results also showed that 3/8 in (10 mm) heat‐strengthened monolithic glass exhibited no fallout, while 3/8 in annealed monolithic glass exhibited very negligible glass fallout. The addition of torsional motions was not found to induce glass fallout in those glass types that resisted glass fallout in previous test

ISSN:0098-8847    

DOI:10.1002/eqe.4290240102

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe two numerical procedures previously presented by the authors to model crack closure during seismic fracture of concrete gravity dams are employed herein to study the 1967 performance of the Koyna dam. First, a brief description of the general procedure is given, followed by the detailed formulation of the force method for simulation of crack closure. The latter was introduced to prevent the hypothetical overlap phenomenon which was originally assumed in the modelling of crack closure by the impulse method. Also presented are the results obtained for a model of the Koyna dam tested on a shaking table to study the cracking process under simplified loading conditions. Satisfactory agreement between the test and numerical results is shown. Finally, the cracking process of the Koyna dam prototype subjected to the 1967 earthquake is evaluated numerically by employing the aforementioned techniques. From the results, it is concluded that both procedures for simulating the impact effect of crack closing predict complete penetration of the crack through the upper part of the dam, which is consistent with the observed prototype behaviour.

ISSN:0098-8847    

DOI:10.1002/eqe.4290240103

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAccelerations and displacements due to dynamic excitation by simulated traffic consisting of two trucks, were measured on the deck and tower of the Alamillo cable‐stayed bridge. Also the dynamic testing program included the measurement with accelerometers of the free‐damped vibration of the 26 cables achieved by means of quick‐releasing force. From these measurements it was possible to obtain the dynamic parameters of the bridge (natural frequencies and damping ratios) and the real forces in the cables. In the paper, only the tests, results and conclusions related to dynamic parameters of the bridge are presented. The objective of the dynamic tests herein described was to validate the mathematical modelling and the wind‐tunnel models used in the dynamic analysis of the bridge in front of traffic and wind‐forces. As the agreement between dynamic parameters of the real bridge and theoretical and scaled models was very satisfactory, the correct dynamic behaviour of the bridge in response to traffic and wind (vortex shedding, flutter, etc.) can be deduced jointly with the correct alignment and expected internal forces in the permanent state in tower

ISSN:0098-8847    

DOI:10.1002/eqe.4290240104

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractWe develop two algorithms for estimating member stiffnesses and masses of a structure from measured modal response in conjunction with a finite element model of the structure. The mathematical model has known geometry and topology and parameterized constitutive properties. A few of the natural frequencies are measured and the corresponding modes are sampled at certain locations in space. The proposed algorithms are based on the concept of minimizing the sum of the squares of errors, specified as an index of discrepancy between the model and the structure, over all of the measured modes. The recursive quadratic programming method is used to solve the non‐linear constrained estimation problem. Both proposed estimators can handle incompletely measured models, have robust convergence, and are amenable to modelling of complex structures. We demonstrate the use of our parameter estimation algorithm by applying it to identify the properties of a building from measured dat

ISSN:0098-8847    

DOI:10.1002/eqe.4290240105

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA large number of parameters affect the inelastic response of an eccentric system. The centre of resistance no longer remains constant due to continuous loading and unloading of various elements of the system in and out of the inelastic region. The objective of this study is to develop the concept of strength eccentricity for asymmetrical structures excited well into the inelastic region in the event of a severe earthquake. A single mass monosymmetric three‐element system is selected. The torsional flexibility parameter is varied so as to obtain nine eccentric configurations covering the entire spectrum of such systems. These models were subjected to S00E component of the El Centro earthquake of 1940 which is considered to be a very severe earthquake. The concept of effective strength eccentricity is introduced which is defined as strength eccentricity at the point of intersection of ductility ratio curves of REE and FEE. It is proposed to provide additional strength in the elements of a torsionally unbalanced system independent of the design eccentricity. Empirical equations are proposed to account for design eccentricity and additional strength as well as distribution of the design strength. The proposed formulation is compared with the torsional provisions of UBC 1991, NBCC 1990 and NZC 1992. It is concluded that additional ductility demand on the REE and FEE designed based on the proposed formulation is almost nil as compared to that given by the three codes. The NZC and UBC require maximum ductility on the REE. The increase in overall strength of the system is least for the proposed formulation as compared to that given by the three codes. NBCC consistently requires the maximum total strength rati

ISSN:0098-8847    

DOI:10.1002/eqe.4290240106

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper explores the potential of a new time domain identification procedure to detect changes in structural dynamic characteristics on the basis of measurements. This procedure is verified using mathematical models simulated on the computer. The experiments involve two eight‐storey steel structures with and without energy devices, and a 47‐storey building at San Francisco during the Loma Prieta earthquake. The recursive instrumental variable method and extended Kalman filter algorithm are used as identification algorithms. An exploratory investigation is made of the usefulness of various indices, such as mode shape and storey drift, that can be extracted accurately from identification to quantify changes in the characteristics of the physical system. It is concluded that the change of storey drift is the key information to the detection of changes in structural parameters, from which the proposed system identification algorithm can be applied with an appropriate inelastic model to simulate the dynamic behaviour of real structures undergoing strong ground motion excitati

ISSN:0098-8847    

DOI:10.1002/eqe.4290240107

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIn the present paper, the boundary element method with exterior collocation was applied to two‐dimensional elastodynamic problems. The stability of the numerical solution was discussed and the collocation rule of source points outside the region being studied was investigated in the frequency domain by means of the computed error in the boundary displacement and the condition number of the coefficient matrix for two typical wave propagation problems. The achieved results are helpful to the practical application of this method to earthquake ground motion analysi

ISSN:0098-8847    

DOI:10.1002/eqe.4290240108

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAn indirect boundary integral method to obtain the three‐dimensional response of an infinitely long, layered, viscoelastic valley of arbitrary cross‐section embedded in a layered viscoelastic half‐space is presented. The valley is excited by homogeneous plane waves impinging at an oblique angle with respect to the axis of the valley. The method and associated computer programs are tested by comparison with available results in the limiting two‐dimensional case of incidence normal to the axis of the valley. Additional comparisons with previous three‐dimensional results obtained by a hybrid finite element‐boundary integral method for cylindrical valleys subjected to obliquely incident waves show large differences. However, the results obtained here for an infinitely long valley appear to be in some agreement with earlier results for an elongated prolate semi‐ellipsoidal valley and with results obtained by a discrete wavenumber boundary element approach. An extensive bibliography on the dynamic response of valleys is a

ISSN:0098-8847    

DOI:10.1002/eqe.4290240109

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractDuring a severe earthquake, steel moment resisting frames are expected to experience significant inelastic deformation in their members and joints. This behaviour is dependent upon several design parameters such as member sizes, frame's overstrength, member deformation capacities and the detailing of components. In this study, the influence of such aspects on the inelastic response of frames is investigated. Inelastic static and dynamic analyses were performed on four frames of different designs for a typical six‐storey building. The frames were designed and detailed in accordance with current North American code requirements. The computed response of each frame was compared with the behaviour expected by the codes. Recommendations for a design procedure are suggested for improving the structural performance of low‐rise steel frames subjected to strong earthquake excitat

ISSN:0098-8847    

DOI:10.1002/eqe.4290240110

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractSeveral types of energy dissipation devices using viscoelastic materials have been proposed to reduce vibration in structures subjected to wind and earthquake excitations. At constant temperature and small strain levels, the mechanical behaviour of Viscoelastic (VE) materials can be described using linear operators. In general, the stiffness and damping matrices of structures using VE devices are frequency dependent; this implies that the classical second‐order differential equations for the modal co‐ordinates are not a complete model for this type of structures. In this paper, the concept of modal coupling in the frequency domain is addressed, expressions for diagonalizable frequency‐dependent stiffness and damping matrices are given, and an iterative technique for the computation of the response of viscoelastic structures is studied. Necessary and sufficient conditions for convergence of the technique are given and numerical examples are developed to illustrate the application of the m

ISSN:0098-8847    

DOI:10.1002/eqe.4290240111

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY