PSD testing of bridges A numerical validation study

Pseudodynamic (PSD) tests were conducted on plywood-sheathed conventional Japanese three-dimensional (3D) wooden structures. Lateral load was applied to the edge beam of specimen structures to generate eccentricity loading. Specimens were based on a combination of shear walls with openings in the loading direction and horizontal diaphragms with different shear stiffness. The principle deformation of the horizontal diaphragm was torsion for rigid diaphragms and shear deformation for flexible diaphragms. Lumped-mass time-history earthquake response analysis was conducted on the tested structures, and additional calculations were conducted on structures with different eccentricity rates. Dynamic analyses were conducted by varying the masses and the resistance of the walls in the loading direction. The simulated peak displacement response in the loading plane agreed comparatively well with the PSD test results. The maximum displacement response on changing the wall resistant ratio showed almost the same tendency as that obtained by changing the mass ratio up to an eccentricity rate of 0.3; however, the maximum displacement response increased markedly beyond an eccentricity rate of 0.4. It was proved that the lumped-mass 3D model proposed in this study was appropriate for conducting a parameter study on the 3D dynamic behavior of timber structures.

The effectiveness of seismic retrofitting of multi-storey multi-bay reinforced concrete (RC)-frame buildings by converting selected bays into new walls through infilling with RC was studied experimentally at the ELSA facility of the Joint Research Centre in Ispra (Italy). A full-scale model was tested with the pseudo-dynamic (PsD) method and consisted of two four-storey (12 m tall) three-bay (8,5 m long) parallel frames linked through 0,15 m slabs with the central bay (2,5 m) infilled with an RC wall. The frames were designed and detailed for gravity loads only and were typical of similar frames built in Cyprus in the 1970s. Different connection details and reinforcement percentages for the two infilled frames were used in order to study their effects in determining structural response. The results of the pseudo-dynamic and cyclic tests performed on the specimen are presented, and conclusions are drawn.

Chapter 12 - Pseudo-Dynamic Tests and Analysis on Semi-Rigidly Jointed Steel Frames

The pseudodynamic (PSD) test method imposes command displacements to a test structure for a given time step. The measured restoring forces and displaced position achieved in the test structure are then used to integrate the equations of motion to determine the command displacements for the next time step. Multi‐directional displacements of the test structure can introduce error in the measured restoring forces and displaced position. The subsequently determined command displacements will not be correct unless the effects of the multi‐directional displacements are considered. This paper presents two approaches for correcting kinematic errors in planar multi‐directional PSD testing, where the test structure is loaded through a rigid loading block. The first approach, referred to as the incremental kinematic transformation method, employs linear displacement transformations within each time step. The second method, referred to as the total kinematic transformation method, is based on accurate nonlinear displacement transformations. Using three displacement sensors and the trigonometric law of cosines, this second method enables the simultaneous nonlinear equations that express the motion of the loading block to be solved without using iteration. The formulation and example applications for each method are given. Results from numerical simulations and laboratory experiments show that the total transformation method maintains accuracy, while the incremental transformation method may accumulate error if the incremental rotation of the loading block is not small over the time step. A procedure for estimating the incremental error in the incremental kinematic transformation method is presented as a means to predict and possibly control the error. Copyright © 2009 John Wiley & Sons, Ltd.

Application of the endurance time methodology on seismic analysis and performance assessment of hydraulic arched tunnels

Steel multi-tiered concentrically braced frames (MT-CBFs) represent a bracing configuration where two or more concentric bracing panels are stacked between the ground and roof levels in tall single-storey buildings. A large proportion of MT-CBFs in Canada are located in low-to-moderate seismic regions (seismic category 0–3) where limited ductility CBFs are often preferred in design. Nevertheless, brace tensile yielding may not occur in all tiers of such frames. Additionally, the analysis and design procedure adopted by the 2019 Canadian steel design standard (CSA S16-19) can become tedious in tall frames with multiple panels. In this paper, the seismic behaviour of limited ductility MT-CBFs in moderate seismic regions of Canada is examined to propose a simplified design method. A set of 16 prototype MT-CBFs is designed in accordance with CSA S16-19, excluding the design requirements prescribed for MT-CBF columns. Nonlinear dynamic analyses are then performed to examine their seismic response. Finally, an efficient design method is proposed in the framework of CSA S16-19.

Testing of a transfer plate by pseudo-dynamic test method with substructure technique

Brookhaven National Laboratory (BNL) is a multidisciplinary laboratory that maintains a primary mission focus the physical sciences, energy sciences, and life sciences, with additional expertise in environmental sciences, energy technologies, and national security. It is managed by Brookhaven Science Associates, LLC, (BSA) under contract with the U. S. Department of Energy (DOE). BNL's Fiscal year 2008 budget was $531.6 million. There are about 2,800 employees, and another 4,300 guest scientists and students who come each year to use the Laboratory's facilities and work with the staff. The BNL Laboratory Directed Research and Development (LDRD) Program reports its status to the U.S. Department of Energy (DOE) annually in March, as required by DOE Order 413.2B, 'Laboratory Directed Research and Development,' April 19, 2006, and the Roles, Responsibilities, and Guidelines for Laboratory Directed Research and Developlnent at the Department of Energy/National Nuclear Security Administration Laboratories dated June 13, 2006. Accordingly, this is our Annual Report in which we describe the Purpose, Approach, Technical Progress and Results, and Specific Accomplishments of all LDRD projects that received funding during Fiscal Year 2008. BNL expended $12 million during Fiscal Year 2008 in support of 69 projects. The program has two categories, the annual Open Call LDRDs and Strategic LDRDs, which combine to meet the overall objectives of the LDRD Program. Proposals are solicited annually for review and approval concurrent with the next fiscal year, October 1. For the open call for proposals, an LDRD Selection Committee, comprised of the Associate Laboratory Directors (ALDs) for the Scientific Directorates, an equal number of scientists recommended by the Brookhaven Council, plus the Assistant Laboratory Director for Policy and Strategic Planning, review the proposals submitted in response to the solicitation. The Open Can LDRD category emphasizes innovative research concepts with limited management filtering to encourage the creativity of individual researchers. The competition is open to all BNL staff in programmatic, scientific, engineering, and technical support areas. Researchers submit their project proposals to the Assistant Laboratory Director for Policy and Strategic Planning. A portion of the LDRD budget is held for the Strategic LDRD (S-LDRD) category. Projects in this category focus on innovative R&D activities that support the strategic agenda of the Laboratory. The Laboratory Director entertains requests or articulates the need for S-LDRD funds at any time. Strategic LDRD Proposals also undergo rigorous peer review; the approach to review is tailored to the size and scope of the proposal. These Projects are driven by special opportunities, including: (1) Research project(s) in support of Laboratory strategic initiatives as defined and articulated by the Director; (2) Research project(s) in support of a Laboratory strategic hire; (3) Evolution of Program Development activities into research and development activities; and (4) ALD proposal(s) to the Director to support unique research opportunities. The goals and objectives of BNL's LDRD Program can be inferred fronl the Program's stated purposes. These are to (1) encourage and support the development of new ideas and technology, (2) promote the early exploration and exploitation of creative and innovative concepts, and (3) develop new 'fundable' R&D projects and programs. The emphasis is clearly articulated by BNL to be on supporting exploratory research 'which could lead to new programs, projects, and directions' for the Laboratory. We explicitly indicate that research conducted under the LDRD Program should be highly innovative, and an element of high risk as to success is acceptable. To be one of the premier DOE National Laboratories, BNL must continuously foster groundbreaking scientific research. At Brookhaven National Laboratory one such method is through its LDRD Program. This discretionary research and development tool is critical in maintaining the scientific excellence and long-term vitality of the Laboratory. Additionally, it is a means to stimulate the scientific community and foster new science and technology ideas, which becomes a major factor in achieving and maintaining staff excellence and a means to address National needs within the overall mission of the DOE and BNL.

초록·키워드 목차 오류제보하기 등록된 정보가 없습니다. ABSTRACT1. 서론2. 실험계획 및 방법3. 실험 결과 및 분석4. 결론참고문헌요약

Recent vibration serviceability problems of many structures have drawn researchers' attention to the walking-induced vibration modelling and assessment of floors and footbridges. Stochastic nature of human-induced vibration and its dependency on numerous conditions significantly reduce the accuracy of the current non-stochastic design procedures and consequently the level of confidence on them. This paper tends to study the performance of two of the most recent design guidelines, UK National Annex to Eurocode 1 (2008) [1] and French Sétra guideline (2006) [2], on real structures and to highlight their advantages and disadvantages. These methods are used to calculate dynamic reactions of a slender and lightly damped pre-stressed concrete slab strip and an as-built footbridge using various loading scenarios such as group loading, spatially unrestricted flow of pedestrians, and crowd loading. The calculated structural responses under first and second harmonics of walking load are further compared with their corresponding experimentally acquired reactions to examine their accuracy and efficiency. Various potential sources of discrepancy in the results of these procedures in comparison with the experimental data, such as missing human-structure interaction effects (e.g. damping), invalid 'perfect periodicity' assumption, limited applicability and unrealistic people correlation are then discussed. Finally the effects of using stationary pedestrians' added damping on performance of considered design models are investigated and briefly discussed. The results of this analysis can provide a comprehensive insight into current design procedures' accuracy and shall be taken as a good starting point for future researches in this area.

Determination of dynamic collapse limit states using the energy-based method for multi-story RC frames subjected to column removal scenarios

This study uses two-dimensional (2D) nonlinear dynamic analyses and one-dimensional (1D) inverse analyses of accelerations from virtual vertical arrays to examine the effect that a flexible shear beam model container has on the dynamic stresses that developed within centrifuge models of level saturated sand. The 2D dynamic analyses are performed using the finite difference program FLAC2D 9.0 with the user-defined constitutive model PM4Sand to obtain cyclic stress ratios on horizontal planes (CSRxy) in the soil. The 1D inverse analyses, which assume 1D shear beam responses, are performed using virtual vertical array data extracted from the 2D dynamic models (i.e., horizontal nodal accelerations along columns) to also obtain cyclic stress ratios on horizontal planes (CSR1D,Σma). Temporal and spatial differences between the CSR1D,Σma and CSRxy from the same analysis model provide a basis for estimating potential errors in the CSRs from either 1D dynamic or 1D inverse analyses of centrifuge array data. The 2D nonlinear dynamic and 1D inverse analysis methods are described, followed by results for three different centrifuge model scenarios. The container effects on cyclic stress ratios for this class of problem are summarized and discussed.

Seismic performance assessment of timber braced frames with dowel connections and slotted-in steel plates: Drift- and energy-based performance indicators

Given the vast advancements in computing power in the last several decades, nonlinear dynamic analysis has gained wide acceptance by practicing engineers as a useful way of assessing and improving the seismic performance of structures. Nonlinear structural analysis software packages give engineers the ability to directly model nonlinear component behavior in detail, resulting in improved understanding of how a building will respond under strong earthquake shaking. One key component, in particular, for understanding the behavior of moment-resisting frames is the plastic rotation of the flexural hinges. Performance-based standards typically use plastic rotation as the primary parameter for defining the acceptance criteria in moment-resisting frames. Since plastic rotation is a key parameter in the seismic damage assessment, the concept as well as the method to calculate this quantity must be understood completely. Though engineers rely on the plastic rotation output from seismic structural analysis software packages to determine acceptable performance, the actual calculation methods used in achieving such plastic rotation quantities usually lay within a so-called “black box”. Based on the outputs obtained from most structural analysis software packages, it can be shown that running an algorithm considering material nonlinearity by itself will produce reasonably accurate results. Moreover, separately running an algorithm considering geometric nonlinearity also can produce accurate results. However, when material nonlinearity is combined with geometric nonlinearity in an analysis, obtaining accurate results or even stable solutions is more difficult. The coupling effect between the two nonlinearities can significantly affect the global response and the local plastic rotation obtained from the analysis and therefore needs to be verified through some analytical means. Yet, the verification process is difficult because a robust analytical framework for calculating plastic rotation is currently unavailable and urgently needed. In view of this gap, an improved analytical approach based on small displacement theory is derived to calculate the plastic rotations of plastic hinges at various locations of moment-resisting frames. Both static and dynamic analysis with nonlinear geometric effects will be incorporated in the derivation. Here the element stiffness matrices are first rigorously derived using a member with plastic hinges in compression, and therefore the coupling of geometric and material nonlinearity effects is included from the beginning of the derivation. Additionally, plastic rotation is handled explicitly by considering this rotation as an additional nonlinear degree-of-freedom. Numerical simulation is performed to calculate the nonlinear static and dynamic responses of simple benchmark models subjected to seismic excitations. Results are compared with various software packages to demonstrate the feasibility of the proposed method in light of the output results among software packages in calculating plastic rotations.

The structural engineering community often deals with the issue of inelastic incursions of the structural response. Although buildings situated in seismic regions are usually designed using elastic analysis, most encounter significant inelastic deformations when major events occur. In general, material nonlinearity is the most important source of nonlinearity considered in the dynamic analysis commonly performed in structural design. In this paper, the recent concept of the force analogy method for 3D structures is developed and integrated into an accurate computational efficient algorithmic routine for nonlinear dynamic analysis of reinforced concrete frames. Moreover, a unique straightforward mathematical model for the numerical implementation of degrading cyclic behavior of structural elements is proposed and further used to simulate the response of a 10 story reinforced concrete frame structure. A set of nonlinear dynamic analyses are performed using the proposed algorithm in order to assess the structural damage in case of different peak ground accelerations seismic recordings. The seismic structural damage is evaluated using both structural response parameters expressed in terms of displacement and energy concepts.