Nonstructural Building Components Research Articles

Sensitivity to Input Parameters of Failure Detection Methods for Out-of-Plane Loaded Glass Panels in Fire

In recent years, glass has been a largely used material for load-bearing or non-structural components in buildings and constructions. For this reason, dedicated calculation methods and approaches are required for the major loading and boundary conditions that are of technical interest for safe design purposes. Among others, the resistance and mechanical performance of glass elements under fire exposure still represents an open challenge. This paper elaborates on the failure detection methods for out-of-plane loaded glass panels that are subjected to fire loading and simultaneous mechanical loads. As known, the conventional method for thermal failure detection is based on the maximum temperature gradient in glass, and its comparison with a set of allowable standardized values. However, especially for ordinary glass components in buildings that are required to sustain combined mechanical loads, the overall structural performance is even more complex to predict. This design issue is given to a combination of pure mechanical aspects (i.e., sustained loads and corresponding stress–strain analysis) and thermo-physical phenomena, that depend on the progressive modification of material properties while increasing temperatures. This research study, accordingly, investigates the sensitivity of input parameters on the failure time of a given glass element under fire and sustained mechanical loads. A major advantage is taken from finite element (FE) numerical analyses and standardized failure detection methods of literature, that are selected for comparative purposes. Further, the paper also introduces the “stress approach” that can be used to quantify (in place of the conventional thermal gradient) the actual effects of assigned thermal exposure and mechanical loads.

Shaking table tests and seismic design suggestions for innovative suspended ceiling systems with detachable metal panels

Recent severe earthquakes revealed that a suspended ceiling system was one of the most fragile non-structural components in buildings, with damage to ceilings causing serious economic losses. Suspended ceilings with detachable panels are widely used because they make the maintenance of facilities above the ceiling convenient, but their poor structural integrity makes them prone to earthquake damage. An innovative type of ceiling system, called a hook-on panel suspended ceiling (HPSC), was proposed to investigate and improve the seismic performance of a suspended ceiling with detachable panels, and full-scale specimens with integrated light fixtures were tested. A total of four shaking table tests were carried out for two types of HPSCs with two boundary conditions. The seismic responses and damage patterns of these HPSCs were compared and analyzed. In addition, the influence of the perimeter constraint on the seismic behavior of the HPSC was investigated. The test results showed that the perimeter constraint of the ceiling effectively reduced seismic response of the flat type of HPSC. After all the loading cases, the frequency and damping ratio of the HPSC did not change significantly, indicating that HPSC was only slightly damaged during the earthquake. The ratio of the panel dropping area to the overall ceiling area was less than 5%, showing that the HPSC had a good seismic performance. Finally, the seismic calculations and countermeasures were provided to facilitate the HPSC as a type of anti-seismic suspended ceiling.

Floor Acceleration Demands in a Twelve-Storey RC Shear Wall Building

The seismic response of acceleration-sensitive non-structural components in buildings has attracted the attention of a significant number of researchers over the past decade. This paper provides the results which improve the state-of-knowledge of the influences that higher vibration modes of structures and nonlinearity of non-structural components have on floor acceleration demands. In order to study these influences, a response-history analysis of a code-designed twelve-storey reinforced concrete building consisting of uncoupled ductile cantilever shear walls was conducted. The obtained absolute floor accelerations were used as a seismic input for linear elastic and nonlinear non-structural components represented by simple single-degree-of-freedom systems, and the main observations and findings related to the studied influences along the building height are presented and discussed. Additionally, the accuracy of the method for the direct determination of peak floor accelerations and floor response (acceleration) spectra recently co-developed by the first author was once again investigated and validated. A brief summary of the method is provided in the paper, along with the main steps in its application. Being relatively simple and sufficiently accurate, the method (in its simplified form) has been recently incorporated into the draft of the new generation of Eurocode 8.

Characterization of a textile waste nonwoven fabric reinforced cement composite for non-structural building components

Large amounts of nonrenewable resources are depleted by the construction industry in addition to the generation of million tons of mineral waste and carbon dioxide gas every year. For the sake of a more sustainable consumption pattern of building materials, as well as for reducing the waste flux to landfills, the use of recycled materials and wastes should be researched and motivated. In this sense, textile waste (TW) nonwoven fabric from residues of the garments and textile industries are investigated as internal reinforcement for cement-based matrices to enhance ductility and cracking control. To this end, an extensive experimental program was carried out to characterize both the mechanical and durability properties of the composite. The results were compared with those obtained from flax nonwoven fabric, taken as a reference (FNH and FH composites). All the composites showed a remarkable improvement in terms of toughness and post-cracking stress-bearing capacity, six being the optimum number of TW reinforcing layers. Through the analysis of the results obtained, the feasibility of using TW composite as a potential construction material in non-structural applications was confirmed. The extension to structural applications of low-medium responsibility is still required further research; nonetheless, the results are promising to this respect.

Evaluation of floor acceleration demands from the 2017 Mexico City code seismic provisions using a continuous elastic model and records of instrumented buildings

This study presents an evaluation of floor acceleration demands for the design of rigid and flexible acceleration-sensitive nonstructural components in buildings, calculated using the most recent Mexico City seismic design provisions, released in 2017. This evaluation includes two approaches: (1) a simplified continuous elastic model and (2) using recordings from 10 instrumented buildings located in Mexico City. The study found that peak floor elastic acceleration demands imposed on rigid nonstructural components into buildings situated in Mexico City might reach values of 4.8 and 6.4 times the peak ground acceleration at rock and soft sites, respectively. The peak elastic acceleration demands imposed on flexible nonstructural components in all floors, estimated using floor response spectra, might be four times larger than the maximum acceleration of the floor at the point of support of the component for buildings located in rock and soft soil. Comparison of results from the two approaches with the current seismic design provisions revealed that the peak acceleration demands and floor response spectra computed with the current 2017 Mexico City seismic design provisions are, in general, adequate.

Demands on nonstructural components in buildings with controlled rocking braced frames

AbstractControlled Rocking Braced Frames (CRBFs) have been developed as a high‐performance seismic force resisting system that can self‐center after an earthquake and avoid structural damage. A CRBF is designed to uplift and rock on its foundation, and this response is controlled using prestressing and energy dissipation devices that are engaged by uplift. Although CRBFs have been shown to have desirable structural performance, a comprehensive assessment of this system must also consider the performance of nonstructural components, which have a significant impact on the safety and economic viability of the system. The purpose of this paper is to evaluate the demands on nonstructural components in buildings with CRBFs in comparison to demands in a reference codified system, taken here as a buckling restrained braced frame (BRBF), as well as to identify which design parameters influence these demands. The responses of various types of nonstructural components, including anchored components, stocky unanchored components that slide, and slender unanchored components that rock, are determined using a cascading analysis approach, where absolute floor accelerations generated from nonlinear response history analyses of each system are used as input for computing the responses of nonstructural components. The results show that the downside of maintaining elastic behavior of the CRBF members is, in general, larger demands on nonstructural components compared to the BRBF system. These demands are not highly influenced by impact during rocking or by the supplemental energy dissipation provided, as the vibration of the CRBF in its higher modes is primarily responsible for the higher demands.

Seismic Demand on Acceleration-Sensitive Nonstructural Components in Viscously Damped Braced Frames

AbstractThis paper investigates the seismic demand on acceleration-sensitive nonstructural components in buildings equipped with fluid viscous dampers. Nonlinear dynamic response analyses were cond...

An approach for sustainable, cost-effective and optimised material design for the prefabricated non-structural components of residential buildings

Offsite prefabrication of the non-structural components of residential and commercial low- and high-rise buildings is becoming increasingly popular due to its sustainability, fast on-site execution, safety and cost-effectiveness. The benefits of offsite prefabrication can be further enhanced if it is coupled with the principles of Design for Manufacturing and Assembly (DfMA), which is based on materials, labours and cost optimisation. Although DfMA has been widely used in automotive and other industries, it is not well-established in the offsite prefabricated construction industry. Moreover, there are no guidelines exist for applying DfMA in prefabricated construction. In this paper, DfMA principles are applied to the most common non-structural members i.e., timber frame wall and the plumbing drainage system of a local residential building in Melbourne, Australia. Site and factory observations for the manufacturing of these components were carried out to collect actual assembly times. Then, using the collected data, the design efficiencies of onsite-, offsite- and DfMA-based prefabrication were computed by developing a user-friendly tool through advanced MATLAB programming. Moreover, from a cost-benefit analysis, DfMA-based prefabrication was found to be better than conventional factory prefabrication of selected non-structural components. Furthermore, based on the results, a pragmatic framework for DfMA based design and execution in a real prefabricated construction project is proposed. The findings of this paper are significant as they can contribute to developing guidelines for DfMA based design of prefabricated non-structural components of residential buildings.

Seismic Floor Acceleration Amplification Based on Instrumented Building Records

Abstract The estimation of seismic forces for acceleration-sensitive nonstructural components (NSCs) in buildings including architectural, mechanical, and electrical systems and building content re...

Simplified calculation of roof accelerations in existing low-rise symmetric unreinforced masonry buildings with flexible diaphragms

A formulation is presented for simplified evaluation of the roof acceleration response for the purpose of assessing non-structural components in unreinforced masonry buildings with flexible diaphragms excluding torsional effects. The method is based on modal calculations that are further studied through nonlinear time-history analysis (NLTHA) of four case study buildings. The NLTHA results for a relatively small level of ground shaking was used to validate the overall ability of the simplified modal method to predict the diaphragm flexibility effects. The NLTHA results were also used to discuss the effects of the building inelastic response in the conservatism of the simplified modal technique. It was found that, in lieu of a comprehensive modal analysis, it is possible to calculate roof accelerations in symmetric low-rise buildings with flexible diaphragms using a simplified two-mode modal method. Based on this study, a predictive method is proposed for conservative estimation of peak roof accelerations in these buildings.

Windstorm Resilient Rural Housing: Lessons learned in Temerloh, Malaysia

In 2019 alone, Temerloh district located in central Peninsular Malaysia has been hit by unpredictable wind storms in localised areas which damaged more than 185 rural homes. This research set out to assess the structural vulnerabilities of damaged rural houses to severe winds in Temerloh and lessons learned from windstorm damage through field surveys of damaged homes between March 2019-August 2019 and supplemented by district-level post-windstorm reconnaissance reports prepared by Malaysia Civil Defense Force (APM) and other information gathered from local government. Results indicate poor performance of structural and non-structural building components in resisting high wind loads due to inadequate design, under-strength of failed building materials and defective construction details. The results of this study could have important implications for government agencies, NGOs, builders, and engineers in assisting rural communities in reconstructing windproof resistant homes and planning for future windstorm risk management efforts specially catered to homeowners in Temerloh.Keywords: Rural housing; Windstorm; Resilience; Malaysia eISSN: 2398-4287 © 2019. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open-access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.DOI: https://doi.org/10.21834/e-bpj.v4i12.1817

Seismic fragility assessment of nonstructural components in unreinforced clay brick masonry buildings

SummaryThe results of an investigation of the probability of earthquake damage to nonstructural unreinforced masonry (URM) components are presented. The components include parapets, chimneys, and out‐of‐plane loaded facades typical of low‐rise pre‐1940 construction in Australia and New Zealand. The study is based on a street survey of component geometry, in situ data on material strength, and simplified mechanical models. Uncertainties in capacity and demand were quantified based on, respectively, stochastic and deterministic approaches. The damage probabilities were compared with relevant guidelines and empirical damage data from three earthquakes. The study established a link between the qualitative damage states reported in existing guidelines and the quantitative URM component damage states. While some median damage state thresholds correlated well with the data from the guidelines, a larger dispersion value was found in the current study due to the large variations in component properties. Comparisons with empirical data suggest that the developed fragility data provide a realistic estimate of nonstructural component damage that occurred in similar buildings, with a reasonable level of conservatism. The outcome is useful in rapid assessment of the seismic risks due to nonstructural component collapse in URM precincts.

Probabilistic modeling and fragility assessment of limestone wall tie connections subjected to wind loads

Public safety has been the main objective of conventional design codes and standards, which provide a good threshold for the performance of structures. However, public safety is not the only objective that can drive the design decisions of building owners and their architectural/engineering design professionals. Minimization of total economic losses in a particular scenario event or over a period of time can also be a major objective for the design and retrofit decisions of building owners. Such economic losses accrue from various cost components that can be caused by damage to structural and/or nonstructural components of buildings, so the uncertainties associated with these damages should be understood. This paper analyzes a set of experimental data for the capacity of limestone wall tie connections in tension to develop probabilistic models. Dependency of tie connection behavior on four testing pre-conditions is also examined. The probabilistic models are then used to illustrate development of fragility curves for the tie connections, by implementing them in limestone veneer façades that are characteristic of those on mid-rise buildings located in the wind environment of Chicago, Illinois.

Increases in Life-Safety Risks to Building Occupants from Induced Earthquakes in the Central United States

Earthquake occurrence rates in some parts of the Central United States have been elevated for a number of years; this increase has been widely attributed to deep wastewater injection associated with oil and gas activities. This induced seismicity has caused damage to buildings and infrastructure and substantial public concern. In March 2016, the U.S. Geological Survey (USGS) published its first earthquake ground motion hazard model that accounts for the elevated seismicity, producing a one-year forecast encompassing both induced and natural earthquakes. To assess the potential impact of the elevated seismicity on buildings and the public, this paper quantifies forecasted risks of (1) building collapse and (2) the falling of nonstructural building components by combining the 2016 USGS hazard model with fragility curves for generic modern code-compliant buildings. The assessment shows significant increases in both types of risk compared to that caused by noninduced earthquakes alone; the magnitude of the increases varies from a few times to more than 100 times, depending on location, building period (which is correlated to building height), alternatives for the hazard model, and type of risk of interest. For exploratory purposes only, we also estimate revised values of the risk-targeted ground motion that are currently used for designing buildings.

Seismic Response of Acceleration-Sensitive Non-Structural Components in Buildings

This paper aims at highlighting the main mechanical parameters controlling the behavior of the so-called ‘acceleration-sensitive’ non-structural components (NSCs). The first reports a short review of the current state of knowledge and the critical issues dealing with the prediction of the seismic response of NSCs. Then, the paper presents the results of a numerical parametric analysis intended to capture the key features of the coupled dynamic response of a two-degree-of-freedom (2DOF) system supposed to be representative of both main structure and ‘non-structural’ component (NSC). The main parameters controlling the dynamic response of NSCs emerge from this study, which could pave the way towards formulating more mechanically consistent relationships for evaluating the peak accelerations induced by seismic shakings on NSCs in buildings.

Structural performance of multi-story mass-timber buildings under tornado-like wind field

Tall mass-timber buildings utilize engineered wood panels to form their main gravity and lateral load resisting systems, which makes them lighter and more flexible than buildings made from concrete, masonry or even steel.In general, drift sensitive components of tall mass-timber buildings could be susceptible to damages due to increased deflection when subjected to extreme wind storms like violent tornadoes. This paper assessed the structural performance of a multi-story mass-timber building, which was designed using the customary 1-in-50 years design wind speed of the 2010 National Building Code of Canada with a load factor of 1.4, under experimentally simulated tornado-like wind fields. In the study, wind loads were obtained from laboratory simulations of tornado-like wind field and atmospheric boundary layer flow at Western University, Canada. Tornadic wind loads from the laboratory tests were scaled to five Enhanced Fujita wind speeds, representing various levels of damage. Dynamic structural analyses were carried out in time-domain to include the possible amplification due to the dynamic component of the excitation and assess floor level inter-story drift and shear force demands for various parameters. The varied parameters were tornado intensity level, the orientation of the building (aerodynamic direction), and critical damping ratio. Based on the obtained results, the vulnerability of drift sensitive components of the study building under tornado-like wind field was estimated. It is shown that strong tornadoes may pose significant damage to drift sensitive non-structural components of multi-story mass-timber buildings. Finally, roadmaps to improve the design of mass-timber buildings in tornado-prone areas are forwarded.

Assessment of dynamic behavior and seismic performance of a high-rise rc coupled wall building

This study evaluates the seismic behavior and performance of a code-based high-rise RC coupled wall building located at the site with high seismicity representative of the West cost of the United States. Modeling approach for dynamic analysis of a coupled wall system is developed based on novel model for RC walls that captures nonlinear axial-flexure-shear (P-M-V) interaction and is validated using detailed experimental data available in the literature, providing the opportunity to analyze the behavior of this system from the new perspective. Seismic performance assessment is conducted considering structural and nonstructural building components based on two performance metrics: repair cost and repair time. The loss metrics are evaluated using FEMA P-58 methodology in conjunction with a realistic repair time model considering frequent (50% in 50 years), rare (10% in 50 years), and very rare (2% in 50 years) earthquake events. Analysis results reveal that strong ground shaking causes significant variation of axial forces in piers of the coupled wall system resulting in P-M-V interaction and considerable shear-related damage (cracking) over most of the wall height, while coupling beam rotations and corresponding damage are relatively small due to their excessive capacity obtained from the code-based design. Although median repair cost is relatively low, less than 6% of construction cost for frequent and rare earthquakes and about 24% for very rare earthquakes, building functionality is impaired at all hazard levels ranging from few weeks for frequent earthquakes to several months for very rare earthquakes, predominantly driven by damage to wall piers and slab-column connections.

Building service life economic loss assessment under sequential seismic events

SummaryAftershocks have been shown to exacerbate earthquake‐induced financial losses by causing further damage to structural and nonstructural components in buildings that have already been affected by a mainshock event and increasing the duration of disrupted functionality. Whereas seismic loss assessment under isolated events has been addressed thoroughly in previous studies, comparatively less has been accomplished in the area of loss assessment under sequences of mainshock‐aftershock ground motions. The main objective of the current study is to formulate a comprehensive framework for quantifying financial losses under sequential seismic events. The proposed framework is capable of accounting for the uncertainties in the state of structure due to accumulation of earthquake‐induced damage, the time‐dependent nature of seismic hazard in the post‐mainshock environment, and the uncertainties in the occurrence of mainshock and aftershock events. Application of the proposed framework to a 4‐story reinforced concrete moment frame shows that consideration of aftershocks could increase lifecycle earthquake‐induced losses by up to 30% compared with mainshock‐only assessments.

In‐plane quasi‐static cyclic tests of nonstructural lightweight steel drywall partitions for seismic performance evaluation

SummaryAn experimental program was performed for evaluating the seismic response and fragilities of nonstructural lightweight steel drywall partitions, also considering the interaction with structural elements and other nonstructural building components, ie, outdoor façade walls. Therefore, in‐plane quasi‐static reversed cyclic tests were carried out on 8 specimens of indoor partition walls infilled in a frame and on 4 specimens of indoor partition walls connected at its ends with transversal outdoor façade walls. Constructive parameters under investigation include type of connections used for connecting the indoor partition walls to the surrounding elements, stud spacing, type of sheathing panels, and type of jointing finishing. The effect of the constructive parameters on the lateral response in secant stiffness and strength is examined. Furthermore, the main damage phenomena observed during the tests are reported and associated to 3 damage limit states distinguished for the required repair level for the tested partition walls. Fragility curves are used for the experimental assessment of seismic fragility of the tested specimens, in accordance with the interstorey drift limits required by the European code. Finally, the quantitative estimation of the repair action costs starting from the damage observation is also developed. The obtained results could be considered a starting point for developing the in‐plane seismic design assisted by testing of lightweight steel drywall partition walls.

Properties of leaves particleboard for sheathing application

Manufacturing particleboard (PB) made of leaves was carried out to make non-structural building components, such as insulation, partition, wall, and sheathing. Raw materials used dry leaves originated from plantation (palm oil leaves) and forest plantation (magahony leaves). The adhesive used was interior type thermosetting commercial resins, namely 10% urea-formaldehyde (UF) based on oven dry leaves. Hardener used for UF resin was 1% and 3% ammonium chloride (NH4Cl) 20% (w/w), respectively. Technically, the target density of PB was 0.8 g/cm3 with the dimension’s size of (250 x 250 x 10) mm3. The pressure, temperature, and time of pressing of the hot press were 25 kgf/cm2, 120C, and 10 minutes, respectively. After conditioning for one week, the PB then was evaluated their physical and mechanical properties according to Japanese Industrial Standard (JIS) A 5908 (2003). Results of this work showed: 1) Both types of PB (palm oil and mahagony leaves) were feasible to be produced for non-structural applications; 2) Addition of hardener enhanced the physical and mechanical properties of PB; 3) It was recommended to enhance the performance of the PB by manipulation of the raw materials and the design.