Milo Clauson

A sediment trap intercomparison study in the Santa Barbara Basin

Four sediment traps of radically different design were deployed in the Santa Barbara Basin for approximately 45 days. The measured fluxes ranged from 370 to 774 g m−2 yr−1 for the different designs. These values lie within flux measurements previously determined for the basin. Compared to the 25-year record (920 g m−2 yr−1), however, all fluxes determined in this experiment are somewhat low. Because this experiment was conducted during a general period of high storm activity and runoff, measurement of greater than average flux was expected. It is probable that the higher flux recorded by the sediments results from a significant input of detritus into the basin by near bottom transport. The chemical composition of trapped material was nearly identical in all four trap designs. The deep cone design, however, had a significantly lower Mn content. Since this trap was the only one in which reducing conditions were produced in the sample container, reduction and mobilization of manganese after collection is believed to have occurred. In spite of the very different designs tested, the factor of two agreement in flux determination and the compositional similarity of the material collected is encouraging for future attempts to directly measure the flux of particulates in the ocean.

Pentachlorphenol migration from treated wood exposed to simulated rainfall

Abstract The leaching of toxins from treated wood poses an, as yet, poorly quantified risk to both plant and animal life. In particular, the leaching of pentachlorophenol (PCP) into rainwater falling on treated wood over aquatic environments, such as bridges, is understudied. Computer models have been developed which predict the leaching of creosote from marine pilings. If data were available, similar models could be developed for PCP-treated bridges and the risk to waterways determined for various structural designs. Providing such data is the objective of this study, where the migration of PCP from treated wood under the influence of simulated rainfall was studied using a simulation system that delivered uniform rainfall rates over-treated wood. The runoff from the treated wood was captured and analyzed with high resolution gas chromatography combined with low resolution mass spectrometry. PCP migrated from treated wood into rainwater runoff at a fairly constant rate of approximately 0.15 g l-1 m-2. Small non-significant deviations were observed with rainfall rate, time, and temperature. We suggest that PCP migration rates from exposed treated wood can be modeled and thereby predict the migration of PCP from this source into the environment.

Wood Materials, Nails, and Sheathing Connections from Early 20th Century Residential Buildings

Assessment of light-frame wood structures for wind and seismic loadings requires engineering information about the wood materials and connections in the subject building. The knowledge base can be developed by inspection and further enriched by knowledge of age effects on materials and connection properties. Nineteen wood-frame structures built between 1905 and 1970 and scheduled for demolition were located through local municipal building departments and sampled for wood materials and nail connections prior to demolition. The project plan was to evaluate the materials from the buildings while watching for trends in materials over time, calculate the expected connection capacity using the materials’ test results, and then compare the calculated allowable connection capacity to tests of single-fastener connections extracted from the same buildings. Insect damage and fungal deterioration were present in many of the structures and were avoided when sampling for test specimens. Inferences are not made regardi...

Use of acoustic assessment to detect decay and assess condition of wooden guardrail posts

Abstract Wood guardrail posts are the most common wood materials currently used in highway construction. Maintenance crews and engineers are often faced with the challenge of rapidly assessing the ...

Effect of inspection holes on flexural properties of Douglas-fir utility poles

Abstract Routine inspection of wood utility poles to detect internal decay involves drilling holes at or about the ground line. While these holes are useful for detecting internal decay, their pres...

Properties of Bamboo–Wood Hybrid Glulam Beams

ABSTRACT Bending and shear characteristics of bamboo–wood hybrid glulam (BWHG) beams were investigated to evaluate the possibility of using laminated bamboo lumber (LBL) as a lamstock for glulam beams in structural application. Moreover, two different resin types were also evaluated for bamboo–wood bond strength. Isocyanate-based resin performed better in terms of bond performance and resulted in higher bending strength and comparable stiffness to that of phenol-resorcinol-formaldehyde resin. The BWHGs performed better than the reported values on Douglas-fir (Pseudotsuga menziesii) glulam beams. Initial results indicate there is potential for LBL to be used as lamstock for glulam beams, which should be investigated further.

Nondestructive bending tests on Douglas-fir utility poles as a potential tool for pole sorting and for prediction of their behavior in service

Abstract Wood poles are a critical part of the electrical transmission system in North America. Wood poles are normally selected on the basis of visual features such as knots, slope of grain or other defects, but there is currently no simple, nondestructive bending (NDB), pre-flexural testing for sorting poles prior to use. In the present paper, the potential for NDB based on bending below the proportional limit was examined to calculate modulus of elasticity (MOE) and thereby predict actual modulus of rupture as determined by destructive bending (MORDB). The investigation was performed on 92 full length 13.3-m long Douglas-fir pole sections. Pre-flexural testing was reasonably correlated with MOEDB, but less well correlated with MORDB. The testing also revealed that visual selection of the best face of a pole, which is used to select a pole oriented to line direction (the “best face”), was poorly correlated with pre-flexing. Increasing the number of NDB tests did not noticeably improve the prediction. The results suggest that pre-flexing might be useful for identifying poles’ performance in service, if more data are available.

Effect of Initial Preservative Treatment on Electrical Conductivity in Douglas-Fir Pole Sections

The effect of copper naphthenate treatment on electrical resistance of Douglas-fir utility poles was compared with similar poles either left untreated or treated with pentachlorophenol (penta). Penta-treated and untreated wood had similar electrical resistance shortly after treatment and after a 3-month outdoor weathering period. Electrical resistance of copper naphthenate–treated wood was more variable but consistently greater, indicating that poles treated with this chemical would not pose an increased risk to utility personnel working on them.

Flexural Creep Apparatus and Testing for Structural Composite Lumber

A specification to test and evaluate the flexural creep and duration of load effects for structural wood-based products was finalized as ASTM D 6815-02. The test method requires relatively large forces be sustained for at least 90 days. Further, the test is conducted in an environment that is moisture and temperature controlled. The typical apparatus for this test uses weights and ratio pulleys, but the heavy loads make loading and unloading difficult and potentially dangerous and the footprint must be large enough to provide space for lifting. This paper describes an apparatus that requires a minimum of floor space and uses hydraulic loading so that it is safer to load and unload. Operation and typical data for the test are used to demonstrate the specification and the apparatus.