Seismic Performance of Anchored Brick Veneer

A study was conducted on the out-of-plane seismic performance of anchored brick veneer with wood-frame backup wall systems, to evaluate prescriptive design requirements and current construction practices. Prescriptive requirements for the design and construction of anchored brick veneer are currently provided by the Masonry Standards Joint Committee (MSJC) Building Code, the International Residential Code (IRC) for Oneand Two-Family Dwellings, and the Brick Industry Association (BIA) Technical Notes. Laboratory tests were conducted on brick-tie-wood subassemblies, comprising two bricks with a corrugated sheet metal tie either nail- or screw-attached to a wood stud, permitting an evaluation of the stiffness, strength, and failure modes for a local portion of a veneer wall system, rather than just of a single tie by itself. Then, full-scale brick veneer wall specimens (two one-story solid walls, as well as a one-and-a-half story wall with a window opening and a gable region) were tested under static and dynamic out-of-plane loading on a shake table. The shake table tests captured the performance of brick veneer wall systems, including interaction and load-sharing between the brick veneer, corrugated sheet metal ties, and wood-frame backup. Finally, all of these test results were used to develop finite element models of brick veneer wall systems, including nonlinear inelastic properties for the tie connections. The experimental and analytical studies showed that the out-of-plane seismic performance of residential anchored brick veneer walls is generally governed by: tensile stiffness and strength properties of the tie connections, as controlled by tie installation details; overall grid spacing of the tie connections, especially for tie installation along the edges and in the upper regions of walls; and, overall wall geometric variations. Damage limit states for single-story residential brick veneer wall systems were established from the experimental and analytical studies as a function of tensile failure of key tie connections, and the seismic fragility of this form of construction was then evaluated. Based on the overall findings, it is recommended that codes incorporate specific requirements for tie connection installation along all brick veneer wall edges, as well as for tie connection installation at reduced spacings in the upper regions of wall panels and near stiffer regions of the backup. Residential anchored brick veneer construction should as a minimum be built in accordance with the current prescriptive code requirements and recommendations, throughout low to moderate seismicity regions of the central and eastern U.S., whereas non-compliant methods of construction commonly substituted in practice are generally not acceptable.published or submitted for publicatio

Experimental assessment and retrofit of full-scale models of existing RC frames

PSD tests on two full-scale models of existing non-seismic resisting RC frame structures are described. The testing program covered several aspects, namely assessment of seismic performance of existing frames without and with infill panels, retrofitting of the bare frame using Selective Retrofitting techniques, strengthening of the infill panels using shotcrete and retrofitting of the frame using K-bracing with shear-link dissipators. The main results from the tests are summarized and discussed and the conclusions are drawn. The tests on the bare frame have shown how vulnerable are existing structures constructed in the 60’s and the beneficial effects of infill panels were confirmed from the tests on the infilled frame. Important improvements, in terms of seismic performance, were achieved by the retrofitting of the frames. However, it was also confirmed that strengthening of the existing infill panels in poorly detailed frames may lead to dangerous ‘local’ failures, such as the shear out of the external columns

Dissipative behaviour of reinforced-earth retaining structures under severe ground motion

This paper focuses on the seismic performance of geosynthetic-reinforced retaining walls (GRWs) that several evidences have shown to be generally adequate. This can be attributed to the dissipation of energy produced by the internal plastic mechanisms activated during the seismic shaking, and to an overall ductile behaviour related to the large deformation that can be accommodated by the soil-reinforcement system. Using a number of numerical computations, this work compares the behaviour of three idealized structures that were conceived in order to have a similar seismic resistance, that however is activated through different plastic mechanisms. The analyses include numerical pseudo-static computations, carried out iteratively to failure, and time-domain nonlinear dynamic analyses, in which acceleration time-histories were applied to the bottom boundary of the same numerical models used for the pseudo-static analyses. The results of the dynamic analyses were interpreted in the light of the plastic mechanisms obtained with the pseudo-static procedure, confirming that GRWs develop local plastic mechanisms during strong motion resulting in a significant improvement of their seismic performance

Experimental and Numerical Studies of the Seismic Performance of Precast Segmental Concrete Columns

Precast segmental concrete column has many advantages, but its applications are limited due to insufficient knowledge about its seismic performance. This thesis aims to investigate the seismic performance of precast segmental column. Cyclic tests and shake table tests were carried out to evaluate the static and dynamic performance of the precast segmental column. Extensive numerical studies were also conducted as supplementary to the experimental results for better understanding of its seismic performance

Seasonally Frozen Soil Effects on the Seismic Performance of Highway Bridges

INE/AUTC 12.0

Assessment of seismic performance of adobe structures in Pakistan and Portugal

Adobe buildings exist in different parts of the world. The construction of these buildings can be carried out economically, using locally available materials and skills that do not require use of modern machinery. Therefore, adobe buildings provide an economic housing option. The construction of adobe structures is carried out based on traditional construction practices which vary from region to region. This paper presents the results of a study which was conducted to study the construction practices of adobe buildings in Pakistan and Portugal in the context of their seismic vulnerability. The adobe buildings in both these countries were found to be subjected to seismic hazard levels which, although is low in some regions, may cause significant damages. Lack of essential elements or details for the adequate seismic performance was found in the adobe buildings in both regions

PEER Testbed Study on a Laboratory Building: Exercising Seismic Performance Assessment

From 2002 to 2004 (years five and six of a ten-year funding cycle), the PEER Center organized the majority of its research around six testbeds. Two buildings and two bridges, a campus, and a transportation network were selected as case studies to “exercise” the PEER performance-based earthquake engineering methodology. All projects involved interdisciplinary teams of researchers, each producing data to be used by other colleagues in their research. The testbeds demonstrated that it is possible to create the data necessary to populate the PEER performancebased framing equation, linking the hazard analysis, the structural analysis, the development of damage measures, loss analysis, and decision variables. This report describes one of the building testbeds—the UC Science Building. The project was chosen to focus attention on the consequences of losses of laboratory contents, particularly downtime. The UC Science testbed evaluated the earthquake hazard and the structural performance of a well-designed recently built reinforced concrete laboratory building using the OpenSees platform. Researchers conducted shake table tests on samples of critical laboratory contents in order to develop fragility curves used to analyze the probability of losses based on equipment failure. The UC Science testbed undertook an extreme case in performance assessment—linking performance of contents to operational failure. The research shows the interdependence of building structure, systems, and contents in performance assessment, and highlights where further research is needed. The Executive Summary provides a short description of the overall testbed research program, while the main body of the report includes summary chapters from individual researchers. More extensive research reports are cited in the reference section of each chapter

Improving the structural reliability of steel frames using posttensioned connections

In this paper, various moment-resisting steel frames (MRSFs) are subjected to 30 narrow-band motions scaled at different ground motion intensity levels in terms of spectral acceleration at first mode of vibration in order to perform incremental dynamic analysis for peak and residual interstory drift demands. The results are used to compute the structural reliability of the steel frames by means of hazard curves for peak and residual drifts. It is observed that the structures exceed the threshold residual drift of 0.5%, which is perceptible to human occupants, and it could lead to human discomfort according to recent investigations. For this reason, posttensioned connections (PTCs) are incorporated into the steel frames in order to improve the structural reliability. The results suggest that the annual rate of exceedance of peak and residual interstory drift demands are reduced with the use of PTC. Thus, the structural reliability of the steel frames with PTC is superior to that of the MRSFs. In particular, the residual drift demands tend to be smaller when PTCs are incorporated in the steel structures.Peer ReviewedPostprint (published version