Wood Decks Research Articles

Evaluation of the slip resistance of modified wood decking products

With increasing global concerns on environmental issues, Chromated Copper Arsenate (CCA) treated wood decking products have been step by step replaced by Wood Plastic Composite (WPC) lumber and heat-treated lumber. The slip resistance of decking is no doubt a critical safety index. Overall, there has not been a proper standard for measuring the slip resistance of WPC products. Canadian Construction Materials Centre (CCMC) uses the static coefficient of friction (μs) to evaluate the slip resistance of WPC products, which stipulates that μs should be larger than 0.50. This study was aimed at measuring the slip resistance of WPC decking products in terms of μs and then comparing with others. There were four types of testing specimens including WPC lumber (WPC), CCA treated spruce lumber (CCAS), heat-treated spruce lumber (HTS) and untreated spruce lumber (UTS). μs was measured, according to ASTM D2394 standard, under two surface conditions (SCs) (dry and wet), two weights of sliding block (WSB) (14 and 20kg), and three sliding speeds (SSs) (10, 50 and 250mm/min). It was discovered that (1) The μs values of CCAS and HTS were always larger than those of UTS and WPC, and only at some specified testing conditions, the μs values of them could reach or exceed 0.50; (2) The μs values of all specimens under wet SC were larger than those under dry SC, and the increase of μs under wet SC was less significant than that under dry SC as the WSB increased from 14 to 20kg; (3) The μs values increased, regardless of the types of specimens, with increasing the WSB from 14 to 20kg; (4) There was no statistically significant difference in μs among three SS values used, 10–50 or 250mm/min.

Roofing Assembly Simulated Heat and Light Test

Abstract The goal of this project is to search for a testing procedure for roof covering products that will radiate both heat and light onto a roof covering and then measure the impact that a given roof covering product has on heat transfer through the entire roofing assembly. Identical roof assemblies were built with ethylene propylene diene terpolymer (EPDM) rubber roof membrane over a wood deck. Sixteen heat lamps were positioned 1.14 m [45 in.] above the roof covering product to provide both heat and light. Thermocouples were placed on the underside of the wood deck and were insulated from outside air. The roofing assembly and the roof covering temperatures were brought to 18°C to 21°C prior to testing. Heat and light were radiated onto the roof coverings for 360 min and the under deck temperature was recorded at 1 min intervals for 600 min. Tested roof coverings included gravel, growing media, coatings, and panels in the form of concrete, ceramic foam, and rubber. The results of the tests have shown data similar to that which were recorded during warm, sunny days. As expected, the highest temperatures were achieved by the uncovered and uncoated black EPDM roof assembly. The temperature of this assembly diminished almost immediately upon the removal of the heat and light source. Thicker layers of growing media and ceramic foam block did not reach the peak temperature until several hours after the heat lamps were turned off. The roof assembly covered with reflective coating showed realistic resistance to the heat and light source. This is a significant advancement in the effort to provide equitable data for all roof coverings. The test provides a standard method of collecting data for traditional roof coverings as well as emerging technology roof covering materials to evaluate a roofing assemblies’ thermal performance from solar heat gain.

Historical floods and dendrochronological dating of a wooden deck in the Old Mint of Segovia, Spain

AbstractDuring recent archaeological work carried out in the 16th‐century Segovia Mint, Spain, a wooden deck of Pinus sylvestris was revealed covering the hydraulic canals. Dendrochronological analyses allowed us to estimate the dates that trees were felled in order to effect repairs to canals damaged after extraordinary flood events. There are at least three age clusters: (1) 1677–1678; (2) 1690–1698–1700; and (3) 1713–1720–1721–1742. By comparing dendrochronological data with both documentary records of repair work and the inventory of historical floods, the dates of the main floods affecting the building between 1583 and 1771 can be identified. Our work is innovative in that it uses tree‐ring dating in historical buildings to reconstruct past flood events, which are then linked to documentary records. It has three main applications: validating documented flood dates, estimating their relative magnitude, and locating new non‐documented flood events or previously unknown historical repair work at this UNESCO World Heritage Site. © 2011 Wiley Periodicals, Inc.

Combining hygrothermal and corrosion models to predict corrosion of metal fasteners embedded in wood

A combined heat, moisture, and corrosion model is presented and used to simulate the corrosion of metal fasteners embedded in solid wood exposed to the exterior environment. First, the moisture content and temperature at the wood/fastener interface is determined at each time step. Then, the amount of corrosion is determined spatially using an empirical corrosion rate model and the inputs of the first step. The result is a corrosion profile along the length of the fastener generated by summing the corrosion depths determined at each time step. We apply the combined model to predict the annual corrosion depth along a metal fastener in wood decks situated in nine different US cities. Corrosion profiles are found to exhibit the same general shape independently of climatic load, with the largest amount of corrosion occurring at 1–5 mm from the wood surface with corrosion depths ranging from 5 μm in Phoenix, Arizona to 45 μm in Hilo, Hawaii. Corrosion is confined to the first 7–20 mm of the fastener below the wood surface. By varying the climatic loads, we find that although there is a definite relation between total annual rain and total annual corrosion, under the same rain loads corrosion is higher for a climate with more evenly distributed rain events. The proposed combined model is able to capture corrosion behavior under varying loading. A sensitivity analysis gives guidelines for future corrosion modeling work for fasteners in wood.

Footbridge Studenci over the Drava River in Maribor, Slovenia

The paper presents the design and construction of the new footbridge Studenci over the Drava River in Maribor. In 2004, the City of Maribor issued an open, anonymous national call for proposals for the reconstruction of the old bridge. In spite of the fact that it was an existing bridge that was to be reconstructed, the new bridge appeared in a new, entirely different, contemporary image. The existing old bridge structure of two steel I-shaped girders with concrete deck was replaced by a new, steel, transparent, space truss structure, with a wooden deck and linear LED illumination. Only the supports from the old bridge were preserved and these also were reconstructed and strengthened. The 'structural solution' as presented in this paper, received a Footbridge Award in 2008.

Coatings To Reduce Wood Preservative Leaching

The efficiency of semitransparent penetrating stains to reduce leaching of wood preservative components was evaluated. Five commercial wood deck finishes were applied to untreated and chromated copper arsenate (CCA), alkaline copper quat (ACQ), and copper azole (CA) treated wood, and leachates were collected and analyzed during 3 years of natural weathering exposure in Toronto, Canada. All stains evaluated effectively reduced the cumulative leaching of all inorganic preservative components by about 60% on average. Although most coatings showed significant film degradation starting around 12 months, the reduced leaching persisted even after 3 years. This suggests that temporary protection of wood with a coating during the early stages of use resulted in long-term reduction in preservative leaching potential. A two-week screening leaching test was able to predict the long-term leaching performance of different coatings reasonably well. Cured coating glass transition temperature (Tg) and liquid coating viscosity were the most important variables affecting a leaching prediction model. To effectively reduce leaching of preservative components from treated wood, coatings should have Tg low enough to withstand stresses caused by freezing in winter and have adequate viscosity to form a barrier film layer on the wood surface.

Creep behavior of bagasse fiber reinforced polymer composites

The creep behavior of bagasse-based composites with virgin and recycled polyvinyl chloride (B/PVC) and high density polyethylene (B/HDPE) as well as a commercial wood and HDPE composite decking material was investigated. The instantaneous deformation and creep rate of all composites at the same loading level increased at higher temperatures. At a constant load level, B/PVC composites had better creep resistance than B/HDPE systems at low temperatures. However, B/PVC composites showed greater temperature-dependence. Several creep models (i.e., Burgers model, Findley’s power law model, and a simpler two-parameter power law model) were used to fit the measured creep data. Time–temperature superposition (TTS) was attempted for long-term creep prediction. The four-element Burgers model and the two-parameter power law model fitted creep curves of the composites well. The TTS principle more accurately predicted the creep response of the PVC composites compared to the HDPE composites.

Structuri architectural-arheologice din centrul istoric București

Structuri architectural-arheologice din centrul istoric București

Product attributes affecting consumer preference for residential deck materials

In many countries, restrictions on the use of traditional preservative treatments have resulted in efforts to develop wood products for outdoor use that are durable, environmentally friendly, and appealing to consumers. In the present study, consumers’ preferences for wooden deck materials were investigated using sensory analysis. The analysis included an analytical sensory profiling of five deck materials, conducted by a trained sensory panel, as well as a hedonic preference study conducted on Norwegian customers. Eighteen visual and tactile attributes were identified, and statistical analysis indicated that these attributes were sufficient to discriminate between the different deck materials. The results imply that consumers prefer deck materials with a homogeneous visual appearance and moderate color intensity. The study demonstrated a successful application of sensory research on wood products and implies that sensory analysis is an appropriate tool to study relationships between hedonic judgments and product characteristics. The study was carried out on wooden deck materials, but the results are probably also relevant for other wood products.

Effects of pretension in bolts on hysteretic responses of moment-carrying timber joints

The adoption of a concept similar to the prestressing technique used in laminated wood decks of bridge structures might increase the initial stiffness or ultimate resistance of dowel-type timber joints by applying pretension to their bolts. This study investigated the effect of pretension in bolts on hysteretic responses and ultimate properties of moment-carrying timber joints with steel side plates. A pretension of 20 kN that yielded a prestress level of 1600 kPa or about 90% of the allowable long-term end-bearing strength of spruce species was applied to the bolts of prestressed joints. The superiority of the prestressed joint over the non-pre-stressed joint was proved by very high hysteretic damping, equivalent viscous damping ratio, and cyclic stiffness. At any given rotation level, hysteretic damping reduction and moment resistance decrement due to continuously reversed loads were found to be small because bolt pretensioning minimized the pinching effect. This study showed that the hysteresis loop of the prestressed joint can be obtained by adding the frictional hysteresis loop due to pretension force into the hysteresis loop of the non-pre-stressed joint. Despite a great increase of initial stiffness, only slight increments in ductility coefficient and ultimate moment resistance were found in the prestressed joint.

Evaluating customer preference for wooden deck materials with age effects

Evaluating customer preference for wooden deck materials with age effects

Long-Term Behavior of Wood-Concrete Composite Floor/Deck Systems with Shear Key Connection Detail

The paper investigates the long-term behavior of wood-concrete composite beams with notched connection detail. The experimental program comprised the characterization of the component materials (wood, concrete, and connection detail) and long-term tests on beam specimens. The beam specimens were monitored during the construction process, and for an overall period of 133 days after the application of the service load. The experimental results have then been extended to the entire service life of the structure using a one-dimensional finite-element model. It was found that the increase in moisture content due to the bleeding of the fresh concrete is not an issue for the durability of the wood deck, and the type of construction (shored or unshored) does not significantly affect the structural performance. The rheological phenomena experienced by the component materials lead to quite large deflections over the entire service life, whereas the variation in stress is not significant. If the limitation of the deflection is required for serviceability considerations, the use of concrete with reduced shrinkage and the precambering of the wood deck are to be recommended. A simplified approach based on closed form solutions for composite beams with smeared flexible connectors is finally proposed for the prediction of the long-term behavior.

Structural assessment of van trailer floor systems with aluminium frame and wood decking

This paper studies the structural performance of two trailer floor systems with identical aluminium frames but different wood decking materials (solid hardwood planks and wood composite panels) when the floor systems are subjected to the forklift wheel loads. Finite element models were developed to simulate the floor response and full-scale static and cyclic loading tests were conducted. To improve the performance of the floor system with wood composite decking, modification of floor configuration was attempted and finite element modelling results predicted higher floor stiffness and load-carrying capacity.

Aluminium Structures in Refurbishment: Case of the Real Ferdinando Bridge on Garigliano River

The use of aluminium alloys is today an emerging activity which competes with steel in many specific fields of structural engineering. A new field of particular interest is the one of structural restoration, where aluminium and its alloys represent a new material whose properties can be exploited in a very promising way. An interesting experience has been the restoration of old suspension bridges in France during the seventies. These structures, built during the 19th century, were made of wooden deck, masonry piers, steel girders and steel suspension cables. Their bad condition required structural consolidation operations, also in view of re-using these bridges in a new improved road planning. After a national competition, in which both steel and aluminium solutions were presented, the French Road Authorities accepted to use an aluminium deck in the retrofitting project of three bridges (the Montmerle and the Trevoux bridges on the Saone river; the Groslee bridge on the Rhone river). They were completed within 1975.In the Montmerle bridge (two 80 m bays) the use of aluminium both for the two longitudinal truss beams with bolted connections and for the deck structures led to the possibility of increasing the weight of the road vehicles, while preserving both the existing cables and piers without significant strengthening . In the retrofit of the Groslee bridge (a single 174 m bay) the new deck structure is made of three longitudinal aluminium truss girders, connected to a light reinforced concrete slab .At the end of the eighties, a structural restoration project of the oldest Italian suspension bridge, the Real Ferdinando bridge on the Garigliano river (1832), had been proposed in the context of a wider rehabilitation program of that area, which wanted to re-use it for a pedestrian connection. This bridge was designed by Luigi Giura in 1828 (Fig. 3) and erected in 1831-32 under the supervision of the King-Ferdinando II. During World War 2 the deck of the bridge was completely destroyed and it was in a bad condition for many years. Considering the positive French experience, it was clear that an aluminium solution would be very appropriate for the planned purpose. But it was necessary to develop a comprehensive comparison between the more classical steel solution and the aluminium one in order to convince the public Authorities. A long procedure of about ten years followed after the first approach to the problem. In 1998 erection of the new aluminium bridge was successfully completed. (A)

Lessons learnt from post-bushfire surveys at the urban interface in Australia

Wildland-Urban Interface (WUI) fires have become a problem of great concern across multiple continents. An important mechanism of structure ignition in WUI fires and urban fires is the production of firebrands. During WUI fires, decking assemblies have been observed to be an ignition vulnerability based on post-fire damage surveys conducted by NIST and elsewhere. The authors have conducted scoping experiments and demonstrated the dangers of the dynamic process of continual, wind-driven firebrand showers landing on decking assemblies for wind speeds of 6 m/s. In this study, eight full-scale experiments were conducted with wood decking assemblies under a wind speed of 8 m/s. The basis for these new investigations was twofold: observe possible vulnerabilities of wood decking assemblies to continuous, wind-driven firebrands at higher wind speed as firebrand accumulation patterns were expected to be influenced by wind speed, and examine if wall ignition occurred due to the burning decking assembly. To this end, sections of wood decking assemblies (1.2 m by 1.2 m) were constructed and attached to a reentrant corner assembly. The deck/reentrant corner assembly was then exposed to continuous, wind-driven firebrand bombardment generated by a full-scale Continuous Feed Firebrand Generator installed in the Fire Research Wind Tunnel Facility (FRWTF) at the Building Research Institute (BRI) in Japan. The mass of firebrands required for flaming ignitions under a wind speed of 8 m/s was considerably less compared with those under a wind speed of 6 m/s. This result is postulated to be due to higher firebrand surface temperatures as the wind speed was increased. For the decking assembly to wall ignition studies, the interface between the decking assembly and the wall appeared to be a weak point; this is not addressed in the current test methods.

Field load tests of an anisotropic-grid timber bridge

This paper details the implementation of an innovative timber bridge technology developed for secondary road applications. A pilot bridge was constructed and field tested under loads comparable to required design loads. A through-girder primary system with transverse floor beams and longitudinal wood deck secondary system are involved. A unique steel hanger system for suspending the transverse floor beams and providing I-beam action under lateral load was configured. Results of the field load test program and analytical predictions from a computer model are described. The pilot bridge proved to be economically competitive and structurally effective.

Old mills, new condos; sound isolation in mill building conversion projects

Up and down the New England Coast, century-old mill buildings are being converted into condominium and apartment buildings amidst one of the biggest housing booms in recent memory. While the inherent acoustical conflicts in multi-family dwelling are not new (oft-cited HUD guidelines are approaching their 40th birthday), the flood of mill conversions is bringing to light a number of new constructions that architects use to chop former factories into discrete living spaces. This paper will present field-collected data and case studies that illustrate some of the problems and common pitfalls associated with mill building conversion projects. Among the construction details discussed include exposed timber ceilings that run continuously across gypsum board partitions, the creative reuse of existing brick walls, and some acoustical properties of wood deck construction common to many mill buildings.

A Probabilistic Arsenic Exposure Assessment for Children Who Contact CCA‐Treated Playsets and Decks, Part 1: Model Methodology, Variability Results, and Model Evaluation

Concerns have been raised regarding the safety of young children who may contact arsenic residues while playing on and around chromated copper arsenate (CCA)-treated wood playsets and decks. Although CCA registrants voluntarily canceled the production of treated wood for residential use in 2003, the potential for exposure from existing structures and surrounding soil still poses concerns. The EPA's Office of Research and Development developed and applied the probabilistic Stochastic Human Exposure and Dose Simulation model for wood preservatives (SHEDS-Wood) to estimate children's absorbed dose of arsenic from CCA. Skin contact with, and nondietary ingestion of, arsenic in soil and wood residues were considered for the population of children in the United States who frequently contact CCA-treated wood playsets and decks. Model analyses were conducted to assess the range in population estimates and the impact of potential mitigation strategies such as the use of sealants and hand washing after play events. The results show predicted central values for lifetime annual average daily dose values for arsenic ranging from 10(-6) to 10(-5) mg/kg/day, with predicted 95th percentiles on the order of 10(-5) mg/kg/day. There were several orders of magnitude between lower and upper percentiles. Residue ingestion via hand-to-mouth contact was determined to be the most significant exposure route for most scenarios. Results of several alternative scenarios were similar to baseline results, except for the scenario with greatly reduced residue concentrations through hypothetical wood sealant applications; in this scenario, exposures were lower, and the soil ingestion route dominated. SHEDS-Wood estimates are typically consistent with, or within the range of, other CCA exposure models.

Load and Resistance Factor Calibration For Wood Bridges

The paper presents the calibration procedure and background data for the development of design code provisions for wood bridges. The structural types considered include sawn lumber stringers, glued-laminated girders, and various wood deck types. Load and resistance parameters are treated as random variables, and therefore, the structural performance is measured in terms of the reliability index. The statistical parameters of dead load and live (traffic) load, are based on the results of previous studies. Material resistance is taken from the available test data, which includes consideration of the post-elastic response. The resistance of components and structural systems is based on the available experimental data and finite element analysis results. Statistical parameters of resistance are computed for deck and girder subsystems as well as individual components. The reliability analysis was performed for wood bridges designed according to the AASHTO Standard Specifications and a significant variation in reliability indices was observed. The recommended load and resistance factors are provided that result in consistent levels of reliability at the target levels.

Water absorption behavior and mechanical properties of lignocellulosic filler–polyolefin bio-composites

To determine certain physical properties, viz. the thickness swelling and water absorption, and mechanical properties, viz. the tensile strength and Izod impact strength, of lignocellulosic filler reinforced polyolefin bio-composites, polyolefin was used as the matrix polymer and rice-husk flour as the reinforcing filler. Wood flour was also used as a reinforcing filler, and commercial particleboard, medium-density fiberboard and solid woods (red pine and birch) were also included in this study, in order to obtain comparative water absorption behavior measurements. Test samples were prepared, in order to determine the physical and mechanical properties of the bio-composites as a function of filler loading and according to filler type as well as with respect to the thermoplastic polymer itself. The thickness swelling and water absorption of the bio-composites slightly increased as the filler loading increased, but to a negligible extent as compared with the wood-based composites (particleboard and fiberboard) and the solid woods (red pine and birch). The mechanical properties of the composites decreased as the filler loading increased, but the composites had an acceptable strength level. It was concluded that these bio-composites are suitable to be used for the interior of bathrooms, wood decks, food packaging, etc.