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This document will outline the findings of three separate and independent studies: Study 1: In or around 1972, an experimental building was constructed. One of the intents of the construction project was to demonstrate advancements in wood building construction design. It was value-engineered throughout. That is, its materials and systems were intended to function at or near design capacity. In 2019, part of the roof of the structure collapsed. This case study investigates two potential factors that led to the failure: stress concentration in excess of the 12 allowable stress for 2 × 4 web members and insufficient plywood sheathing to support live loads 13 caused by large rain events. Study 2: As a building material, cross laminated timber (CLT) has exponentially grown in popularity recently. Although performing superior to numerous other popular building materials, a consistent issue presented in wood construction is the effect of moisture on performance. This study looks to investigate the effect of moisture content on the performance of a 2-way dowel type fastener system loaded in shear perpendicular to the major strength axis. It was found that the peak load capacity of the specimens was not affected by the moisture content of the CLT. However, yield strength increased as the moisture content decreased. Lastly it was found that the failure mode changed from ductile to brittle as specimens became drier than 12% moisture content by mass. Study 3: Inherently, the weak point of any structure is the connection system. This phenomenon is particularly apparent in wooden structures as dowel type fasteners place tremendous amounts of stress perpendicular to the grain of the wood, as well as shear stress under the bolt. In hopes of mitigating this behavior, fiberglass reinforcement of these samples is examined to see if both failure mode as well as overall performance of these fasteners could be improved with reinforcement. It was found that fiberglass significantly reduced the standard deviation of failure strength of fasteners, significantly increased the overall strength of the fasteners, increased the efficiency of the fasteners, and finally increased the probability of bearing failure opposed to block shear failure.

Current fire-spread models are based largely on empirical correlations based on fires burning through dead pine needles. There is a need to increase the accuracy of modeling wildfires in live vegetation. This project investigates the quantitative and qualitative ignition characteristics of eight live fuels, four from southern California (manzanita, scrub oak, ceanothus, and chamise) and four from Utah (canyon maple, gambel oak, big sagebrush, and Utah juniper). Individual leaves were observed as they were exposed to hot gases from a flat flame burner. The broadleaf species from both California and Utah had noticeable surface changes during the ignition process. All fresh samples showed a color change on the leaf surface from a light dusty color to a dark wet color. This is likely due to the melting of the waxy protective layer. Samples of scrub oak, manzanita, ceanothus, canyon maple, and gambel oak at moderate moisture contents (50 to 75%) exhibited bubbling under the leaf surface. Liquid droplets were observed on the surface of Manzanita samples at moisture contents near 75%, while bursting was observed on the surface at moisture contents near 100%. This bursting is due to evaporation of the moisture inside the leaf causing internal pressures to exceed the surface strength of the leaf. Ignition was defined as the time when the first visible gaseous flame was observed near the leaf surface. Measurements of the time to ignition and the temperature at ignition were performed for all broadleaf species. A large degree of scatter was observed in the quantitative ignition data, due largely to variations in leaf thickness and moisture content. Time to ignition was found to correlate with sample thickness and the mass of moisture in the sample. Ignition temperature was constant for varying moisture mass but appeared to increase with thickness. The burning time, defined as the duration of a visible flame near the leaf, was found to correlate roughly with leaf mass. Several types of correlations were made to describe ignition temperature and ignition time as a function of leaf thickness and mass of moisture.

Timber is becoming an increasingly popular construction material particularly due to its great environmental properties. Just alone around Linnaeus University in Växjö city, dozens of multistory buildings in timber have risen. As the demand for more timber construction is becoming popular, the understanding of timber design must evolve at the same pace. One of the most important parts of timber construction are the connections that hold everything together. One variable that is used to design connections is the embedment behavior. This thesis examined how the embedment behavior of a steel dowel in wood is influenced by moisture content, assembly history, and artificial cracks. In this case the assembly history refers to if the drilling and insertion of the steel dowel was done before or after drying or wetting the specimen. The idea behind the artificial crack was to achieve something similar to a real crack where the crack was created with a precision saw to separate the fibers parallel to the grain. The embedment behavior was studied by means of embedment strength, elastic- and plastic embedment stiffness. In total, 140 embedment experiments were conducted to study the embedment behavior of the dowel in wood. All embedment experiments were carried out parallel to the fiber direction using two species of wood, spruce and birch. Each experimental series had its own attributes to allow a comparison of how the embedment behavior is influenced by moisture content, assembly history, and artificial cracks. The data from the experiments was then used as input to create computer models where the beam on foundation modeling approach was used in conjunction with the finite element computer program Abaqus. A timber-steel-timber connection was modeled to study the influence of the side timber member thickness on the overall strength. The results of the experiments showed that the moisture content and the assembly history can potentially affect the embedment strength and the elastic, and the plastic embedment stiffness. The series that studied the influence of artificial cracks showed that mostly the embedment strength and elastic embedment stiffness are affected by artificial cracks. The numerical simulations indicated that the moisture profile from the experimental data had less influence on the strength for thicker timber side members than it did on thinner. In general, this thesis provides new insights and a better understanding of how the embedment behavior is influenced by moisture content, assembly history, and artificial cracks.

In the construction of highways, airports, and other structures, the compaction of soils is needed to improve its strength. In 1933 Proctor developed a laboratory compaction test to determine the maximum dry density of compacted soils, which can be used for specifications of field compaction. The Compaction of soils is influenced by many factors, the most common are the moisture content, the soil type and the applied compaction energy. The objective of this research is the analysis of the maximum dry density values based on the soil classification and characterization. The method of choice in the determination of the maximum dry density from different soils was the Standard Proctor Test following the procedure for the standard Proctor test as is explained in ASTM Test Designation D-698. From this investigation, the maximum dry density of eight types of sands was obtained, the sands were classified by using the Unified Soil Classification System. The influence on the maximum dry density of the type of sands, type of fines, amount of fines and distribution of the grain size was determined, followed by a sensitivity analysis that measured the influence of these parameters on the obtained maximum dry density. The research revealed some correlations between the maximum dry density of soils with the type of fines, the fines content and the Uniformity Coefficient. These correlations were measured and some particular behavioral trends were encountered and analyzed. It was found that well-graded sands have higher maximum dry density than poorly graded when the soils have the same fines content, also it was encountered that plastic fines tend to increase the maximum dry density.

Oriented strandboard (OSB) is a wood-based composite product with the largest market share for residential and commercial construction. OSB composite products have introduced variability in their physical and mechanical properties due to their raw material and process variation. Reliable in-line non-destructive evaluation (NDE) devices are needed to rapidly determine OSB panel product quality during and after the manufacturing process. Wood specific gravity (SG) and moisture content (MC) play an important role in the wood composite manufacturing process. A real-time after-press monitoring device for locating SG and MC variations can supply information needed to control and improve mat formation, hot press schedules, detect MC-related problems, reduce product variation, and perform final product quality inspection. No real-time non-contact NDE methods are available for simultaneous detection of MC and SG variation. In this research, the radio frequency (RF) scanning technique was used to evaluate the MC and SG of OSB. The numerical simulation method assisted in developing RF sensors to nondestructively evaluate MC and SG of OSB composite specimens. MC and SG prediction models were derived based on RF testing results. The model behavior between relative humidity conditioned method and oven-drying conditioning method were compared. The results indicated the RF scanning technique can be successfully used as a NDE tool to measure MC and SG of OSB panel products. Numerical simulation can help deciding RF sensor geometry successfully and accurately. The MC and SG of OSB can be predicted with the models developed with the procedure used in this study. The RF scanning results are not only influenced by material physical properties, but also influenced by their MC conditioning method, such as relative humidity conditioned method and oven-drying conditioning method.

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Quarry fines are by-products of the aggregate extraction and productionprocesses. Because such fine material cannot be marketed, it becomes aburden for the aggregate industry, resulting in stockpiles of financiallyunexploited material. Even though previous research has been focused onminimizing the generation of quarry fines, far too little attention has beenpaid to maximizing their utilization instead. The aim of this thesis is toinvestigate whether 0/2 mm and 0/4 mm quarry fines can be utilized asalternative materials in the construction industry, specifically in theunbound layer of a road or as filling against a bridge. The methodologyconsisted of four laboratory tests that investigated the water content,particle size distribution and percentage of filler content, optimummoisture content (OMC) and maximum dry density (MDD) relationshipas well as bearing capacity of the materials. The results show that theamount of filler content (<0.063 mm) can significantly impact thematerial’s water-holding capacity as well as its compaction capabilities.After comparing the bearing capacity measurements to the technicalrequirements of the Swedish Transport Administration, it was found thatthe 0/2 mm fits the necessary requirements for use in the unbound layerof either a flexible or rigid pavement but not as filling against a bridge.Further research is needed to determine the material’s relationship towater absorption and resistance to freezing and thawing cycles, as it isdifficult to assess its suitability for road construction solely on theseresults; however, despite its limitations, the study provides some valuableinsights into the potential applications of quarry fines.

En av de saker som avgör hyggesresters värde som bränsle är dess fukthalt. Det vore bra om det gick att uppskatta fukthalten hos hyggesrester som lagras utomhus i högar, utan att någon undersökning av materialet behöver göras. Syftet med detta examensarbete var att finna ett sätt att uppskatta fukthalten med hjälp av information om vädret, exempelvis nederbördsmängd, temperatur och molnighet, på den plats på vilken hyggesresterna lagras. Examensarbetet har inte lett fram till någon metod som på ett tillförlitligt sätt kan uppskatta fukthalten med kännedom endast om var (och därmed kännedom om ungefärlig väderlek) som hyggesresterna lagras. Fukthalten tycks i hög grad styras av andra faktorer än de som är kända i denna studie. De okända faktorerna är exempelvis trädslag, kvistarnas tjocklek, markbeskaffenhet och placering i förhållande till omgivande terräng.