Plow Power Requirements for Forestry Site Preparation
Abstract In this field study, data were collected to determine power requirements required by a trailing site preparation plow and the magnitudes of dynamic forces experienced by a plow during normal operation and during impact with stumps or other obstructions. Drawbar pull data were collected from five different tillage treatments on a recently harvested loblolly pine (Pinus taeda) site in central Alabama. The five treatments were: 1) a coulter, ripping shank, and four bedding disks; 2) a coulter, ripping shank, and two bedding disks; 3) a coulter and ripping shank; 4) a coulter alone; and 5) a ripping shank alone. A 330 kN [75 000 lb] capacity tension load cell was used to measure the drawbar load, a GPS receiver recorded tractor speed, four direct current displacement transducers (DCDT’s) monitored the depth of the disks, and two optical tachometers measured the speed of the tractor’s front and rear drive shafts. Each treatment produced significantly different drawbar loads (to alpha levels less than 0.001). The resulting mean loads were 46.0 kN [10 300 lb], 33.5 kN [7530 lb], 31.5 kN [7080 lb], 15.8 kN [3560 lb], and 43.4 kN [9760 lb] for treatments one through five, respectively. Maximum recorded drawbar load during a collision with a stump was 338.9 kN [76 188 lb].
RECOVERY OF PRODUCTIVITY OF ONTARIO SOILS DISTURBED BY AN OIL PIPELINE INSTALLATION
Measurement of soil properties and field-crop yields on cropland traversed by the Sarnia-Montreal oil pipeline indicated that pipeline isntallation detrimentally affected both crop yields and soil physical-chemical properties in the first year after construction. After 5 yr, relative yields improved although reductions still persisted at most row-cropped sites. However, alfalfa yields at two sites appeared to be unaffected by pipeline construction. Soil mixing and compaction on the right-of-way were most prevalent on medium- to fine-textured soils. Compaction did not appear to be a problem at a coarse-textured site. Soil chemical data indicated that spoil (subsoil) materials from the trench were spread across the right-of-way at most sites. Diluted soil organic matter levels in the right-of-way adversely affected nitrogen status. Medium- to fine-textured right-of-way soils had reduced porosities and hydraulic conductivities, but increased strengths compared with undisturbed adjacent soils.
Tests of composite beams with web holes
Tests of composite beams comprising a concrete slab supported on a steel deck and a steel wide-flange shape containing large web openings are described. Special attention is directed to the amount of shear connection between slab and steel section in the region of a web hole, and on the effect of construction loads acting on the steel section prior to composite action being effective.It is shown that limited shear connection at the hole will significantly affect the strength when loading produces a high shear-to-moment ratio, and a theory is presented which conservatively takes this into account. The effect of construction loads on unshored construction is shown to be small when these do not exceed 60% of the non-composite beam resistance at the hole.