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Non‐structural elements (NSEs) are not designed to be part of the structural load‐bearing system of a building but are subjected to the same dynamic environment as the supporting structure during an earthquake. Non‐structural damage and ensuing losses have exceeded structural damage and losses in many buildings during recent earthquakes that have occurred in urban regions around the world. Damage to NSEs is strongly influenced by the amplitude, the frequency content and the duration of floor motions. Although the effects of amplitude and frequency content of floor motions are well captured by floor response spectra, little attention has been given on the characterisation of floor motion duration and how it can impact damage to NSEs, particularly for those responding in the inelastic range. To contribute to a better understanding of these issues, this paper develops a probabilistic strong floor motion duration model through multiple stripes non‐linear time‐history analyses of a population of 100 code‐compliant reinforced concrete frame building models designed for a medium‐to‐high seismicity site in Italy. The resulting probabilistic model can be used when selecting historical or generating synthetic floor motions for the seismic response assessment of NSEs or when generating shake‐table test records for the seismic qualification of NSEs. [ABSTRACT FROM AUTHOR]

The economic losses observed in the last decades following moderate and large seismic events have demonstrated the importance of considering structural and nonstructural responses to evaluate the seismic performance of a building. In this regard, the implementation of fluid viscous dampers can improve the seismic performance of buildings, however, the conventional seismic design procedures of viscously damped structures focus on reducing the induced structural displacement while neglecting the acceleration response, ignoring the influence of different design parameters on the overall seismic response. This study assesses the seismic performance of steel moment-resisting framed buildings retrofitted with fluid viscous dampers by comparing their expected annual loss. To achieve this, three archetype buildings were retrofitted with different configurations of fluid viscous dampers and were subjected to nonlinear time-history analysis using the FEMA P695 far-field ground motion set as seismic input, retaining their peak story drifts, residual drifts, and peak floor accelerations, and computing their probability of collapse. The archetype buildings were also equipped with nonstructural elements and contents typical of office use, and the expected annual loss was computed using the procedure and tools proposed by the FEMA P-58 methodology. The results show that the design parameters of fluid viscous dampers can have a significant effect on the expected annual loss, with some configurations showing expected losses larger than those of the archetype buildings without dampers. In addition, it was observed that the lower expected annual loss tends to be associated with fluid viscous dampers with high axial stiffness and mid-range values of the other design parameters, such as 20% of supplemental damping and velocity exponent values near 0.5. • Inefficient implementations of fluid viscous dampers can lead to high expected annual loss values. • Highly nonlinear viscous dampers can exhibit high expected annual loss values. • The axial stiffness of the maxwell material significantly modifies the response of the buildings. • Smaller expected annual losses were obtained with fluid viscous dampers that balanced acceleration and displacement responses. [ABSTRACT FROM AUTHOR]

Observations from recent earthquakes have repeatedly demonstrated that damage to non-structural elements can significantly compromise the capacity of critical facilities to continue services during times of crises. Performance-based seismic design requires the harmonization of performances between structural and non-structural elements. Among the multitude of non-structural typologies, the seismic performance of piping systems is of paramount importance in order to guarantee the immediate post-event functionality of critical facilities. Few research studies are available in the literature that provide information on the seismic response of piping systems, and in particular of suspended piping restraint installations. This paper presents and discusses the results of an experimental program designed to evaluate the seismic behavior of suspended piping restraint installations. Four typologies of suspended piping restraint installations were tested under monotonic and reversed cyclic loading to determine their hysteretic responses and failure modes and to evaluate key response parameters. [ABSTRACT FROM AUTHOR]

Summary: The achievement of adequate performance objectives for buildings under increasing seismic intensities is not only related to the performance of structural members but also to the behavior of nonstructural elements. The need to properly design nonstructural elements for earthquakes has been largely demonstrated in the last few years and has become an important objective within the earthquake engineering community. A crucial aspect in the proper design of nonstructural elements is the definition of the seismic demand in terms of both absolute acceleration and relative displacement floor response spectra. In the first part of this study, relative displacement and absolute acceleration floor response spectra were computed for four reinforced concrete moment‐resisting archetype frames via dynamic time‐history analyses and were compared with floor response spectra predicted by means of two recent simplified methodologies available in the literature. It was observed that one of the existing methodologies is generally unable to predict consistent absolute acceleration and relative displacement floor response spectra. An improved procedure is developed for estimating consistent floor response spectra for building structures subjected to low and medium‐high seismic intensities. This new procedure improves the predictions of a relative displacement floor response spectrum by constraining its ordinates at long nonstructural periods to the expected peak absolute displacement of the floor. The resulting acceleration and relative displacement response spectra are then consistently related by the well‐known pseudo‐spectral relationship over the entire nonstructural period range. The effectiveness of the proposed methodology was appraised against floor response spectra computed from nonlinear time‐history analyses. [ABSTRACT FROM AUTHOR]

Thin-wall water piping systems are key to the functionality of important facilities, such as hospitals and schools. Recent earthquakes have demonstrated the vulnerability of these systems. Conventional bracing of thin-wall water piping systems does not guarantee adequate seismic performance. Due to their flexibility, dynamic amplification of long piping runs between bracing elements can occur. This paper evaluates, through a case study, the feasibility of introducing viscous dampers within bracing elements of suspended thin-wall water piping systems to improve seismic performance. Three-dimensional dynamic response analyses were conducted on a suspended thin-wall water piping system under seismic floor motions of various intensities. The dynamic response of the piping system with viscously damped bracing is compared to that of the unbraced and conventionally braced piping system. The numerical results indicate an improvement in seismic response for viscously damped braced configurations. The properties of the viscous dampers that causes the largest reductions in the seismic response of the piping system are noted and practical implementation aspects are discussed. [ABSTRACT FROM AUTHOR]

Rigid wall-flexible diaphragm (RWFD) buildings are a common type of single-story construction in North America, Europe, and New Zealand that incorporate rigid in-plane concrete or masonry walls and flexible in-plane wood, steel, or hybrid roof diaphragms. RWFD buildings have shown poor seismic performance during past earthquake events. In particular, it has been observed that the global seismic response is dominated by the response of the diaphragm, which is mainly attributed to large in-plane diaphragm displacements that significantly exceed the displacements of in-plane walls. In this study, the concept of distributed yielding in the flexible diaphragm by weakening certain intermediate diaphragm zones is explored as a cost-effective means to improve the seismic collapse capacity of RWFD buildings and mitigate their seismic vulnerability. A two-dimensional numerical framework was developed specifically for analyzing RWFD buildings and was used to evaluate the proposed concept. Results of nonlinear dynamic time-history response analyses conducted on a typical RWFD building incorporating a wood roof diaphragm show that distributing the inelastic response of the flexible diaphragm along its span is beneficial to the seismic collapse capacity of RWFD buildings. A seismic design approach based on this concept is also formulated. [ABSTRACT FROM AUTHOR]

This second of two companion articles examines the efficiency of a number of hysteresis models to simulate the nonlinear moment-rotation behavior of sprinkler piping tee joints made of various materials and connection types. The proposed hysteresis models are capable of capturing the strength degradation, change of stiffness during unloading, as well as energy dissipation of full-scale sprinkler joints tested by the authors in a previous study. The hysteresis models were then embodied in nonlinear rotational springs at joints combined with elastic beam elements for the piping segments to capture the seismic response of full-scale fire sprinkler piping systems. These system level numerical models were validated through simulations based on the seismic tests presented in the first companion article. Nonlinear dynamic response-history analyses adequately predict the seismic response of the test specimens in terms of displacement, acceleration, and moment-rotation at the piping joints. The proposed numerical models represent a useful tool to assess the seismic demands of pressurized fire sprinkler piping systems in buildings. [ABSTRACT FROM AUTHOR]

This first of two companion articles presents the results of an experimental program designed to evaluate the seismic behavior of fire extinguishing sprinkler piping systems. Three full-scale pressurized sprinkler piping specimens made of different materials and joint arrangements were tested with various levels of seismic bracing under dynamic loading on the University at Buffalo Nonstructural Component Simulator. All three fully braced specimens performed well under a Maximum Considered Earthquake (MCE) level of loading, validating current code-based requirements for bracing system design. However, unbraced systems, which are typically installed in low to moderate seismic regions or could exist in older construction in active seismic zones, did not perform as well as the fully braced systems. Damage to sprinkler heads, failures of vertical hangers, as well as a complete branch line fracture, were observed during the tests. [ABSTRACT FROM AUTHOR]

A planar rigid-body dynamics formulation describing the seismic behavior of a squat rectangular rigid body initially resting on an inclined rigid plane is presented. The downslope motion of the body is limited by a rigid boundary perpendicular to the inclined plane. This type of problem appears in several practical applications. Coulomb and hysteretic friction with velocity- and pressure-dependent properties are considered at the body-to-ground interface. The weaknesses of hysteretic friction models incorporating static and kinetic velocity-dependent components are identified and remedied. Impact models for collision of the body with the rigid boundary and the inclined plane are also derived. The formulation is embodied in a numerical model through a dedicated computer code. A comparative study is conducted to demonstrate the effects on the body response of major model characteristics, including the rigid boundary; inclination angle; Coulomb, hysteretic, and combined Coulomb-hysteretic friction; and velocity dependence of the frictional properties. It is shown that the presence of the rigid boundary considerably affects the body response, and that small inclination angles can significantly limit the outward body displacement. [ABSTRACT FROM AUTHOR]

A simple numerical model to predict the dynamic characteristics, quasistatic pushover, and seismic response of woodframe buildings is presented. In this model the building structure is composed of two primary components: rigid horizontal diaphragms and nonlinear lateral load resisting shear wall elements. The actual three-dimensional building is degenerated into a two-dimensional planar model using zero-height shear wall spring elements connected between adjacent diaphragms or the foundation. The degrading strength and stiffness hysteretic behavior of each wood shear wall in the building can be characterized using an associated numerical model that predicts the walls load-displacement response under general quasistatic cyclic loading. In turn, in this model, the hysteretic behavior of each shear wall is represented by an equivalent nonlinear shear spring element. With this simple approach the response of the building is defined in terms of only three degrees of freedom per floor. This numerical model has been incorporated into the computer program SAWS (seismic analysis of woodframe structures). This paper discusses model formulation. In Part II, the predictive capabilities of this program are compared with recent shake table tests performed on a full-scale two-story woodframe house. [ABSTRACT FROM AUTHOR]

This is the second of two companion papers on the seismic analysis of woodframe structures. In Part I, a simple numerical model was formulated to predict the dynamic characteristics, quasistatic pushover, and seismic response of woodframe buildings. This numerical model has been incorporated into the computer program SAWS (seismic analysis of woodframe structures). Here in Part II, attention turns to implementation and verification of the SAWS model. To this end, the predictive capabilities of the SAWS program are compared with experimental results obtained from recent shake table tests performed on a full-scale two-story woodframe house under the CUREE-Caltech Woodframe Project. It is shown that the SAWS computer program provides reasonably accurate estimates of the dynamic characteristics, quasistatic pushover, and seismic response of the test structure. Furthermore, the SAWS program requires a minimum amount of data input and provides a fast computational turnaround time in which to analyze a given structure. As a result, this simple numerical may be a useful structural analysis tool for practicing engineers and researchers involved in the seismic design and/or analysis of woodframe structures. [ABSTRACT FROM AUTHOR]

The development of low-damage steel moment resisting connections for seismic applications provides designers with techniques to dissipate energy without relying on plastic deformations of beam sections, thus avoiding connection strength and stiffness deterioration and providing the opportunity of adding a self-centering mechanism to avoid residual displacements. In this paper, the system-level performance of two low-damage connections, the sliding hinge joint (SHJ) connection and the self-centering sliding hinge joint (SCSHJ) connection, is evaluated using analytical models. New component models are developed for each of the connections and validated using available experimental results. The global performance of three steel frames of different heights, using either the SHJ connection or SCSHJ connection, are then compared to otherwise identical frames with either pre-Northridge (PRENORTH) connections or reduced beam section (RBS) connections. The benefits of these new connections for the global performance of the frames are presented through fragility curves for 27 response indices, comprising three engineering demand parameters (maximum inter-story drift, residual drifts, and accelerations) under three earthquake hazard types (shallow crustal, subduction, and main-shock-after-shock combinations) for three performance objectives. The global performance of the frames with the SHJ connection is similar to that of frames with the RBS connection, while avoiding yielding and damage in the connections. The SCSHJ connections further enhance the good performance of the SHJ connection by also reducing residual drifts and peak floor accelerations. This improvement in performance translates directly to reductions in the expected annual loss, particularly for structures exposed to longer duration ground motions or main-shock-after-shock sequences. • Presents models for both the newly developed sliding hinge joint (SHJ) and self-centering sliding hinge joint (SCSHJ) steel moment resisting connections. • Compares the global performance of three different frame heights using either non-ductile, pre-qualified, SHJ, or SCSHJ connections. • Identifies that the SCSHJ connections has the greatest benefit during subduction earthquakes and during main-shock after-shock ground motion sequences. • Demonstrates that the SCSHJ connections has the greatest life-cycle benefits to taller structures more susceptible to longer duration ground motions. [ABSTRACT FROM AUTHOR]

The seismic performance of non-structural elements is now recognized to be a key issue in the seismic assessment and earthquake related loss estimation of buildings, both at the individual and regional scale. The evaluation of the seismic demand on non-structural elements in many modern building codes is often based on inaccurate distributions of floor accelerations. For this reason, some design oriented simplified methodologies have been developed recently to predict floor response spectra in reinforced concrete buildings. Although the influence of masonry infills on the seismic performance of reinforced concrete buildings has been widely demonstrated, infills are generally neglected both in the design and in the evaluation of floor response spectra, which could lead to un-conservative design of non-structural elements. In this paper, the effect of masonry infills on absolute acceleration and relative displacement floor response spectra for reinforced concrete buildings subjected to frequent (serviceability level) earthquakes is investigated through a probabilistic framework. A database of one hundred masonry infilled reinforced concrete frames, representative of the European context, was generated and each building analyzed through nonlinear time history analyses. From the results of these analyses, the acceleration and displacement response spectra at different floor levels of both bare and infilled frame archetypes were then computed. The effectiveness of the most common assumptions made in regional risk models to estimate the non-structural losses is investigated and a first attempt at a more refined approach taking into account the effect of masonry infills is proposed. [ABSTRACT FROM AUTHOR]