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Groton is a town in Massachusetts, located approximately 40 miles away from Boston in the Northwest. Groton has an area of 37 square miles of which 2.7% is water. There are several surroundinghills of which the most characteristic one is Gibbet Hill, right in the center of the town. Regarding total area, Grotonis the largest town within state Massachusetts.
Nashua Rivel flows through the area of Groton. There are also severalbrooks, streams and ponds in the area. Over 30% of the land of Groton is a protected open space.
These conservation areas are mostly open to the public, and has a well-maintained trail network. The Groton Trails Committee is responsible for developing and maintaining these areas. With over 100 trails that comprises of a total 100 miles. The main aim of the Friends of The Groton Trails Network, who maintains the website of the scene, is to encourage residents to conservation lands being so close to their living area. They also organize festivals to introduce hiking to the public, and to hold races as well.
For thousands of years, the area of Groton was settled by indigenous peoples. The most dominant tribes were the Nipmuc and the Nashaway Indian tribes.
Europeans came to the region and incorporated the settlement in 1655, with the name Groton. The name was granted after Groton, Suffolk, England. They founded the Plantation of Groton, which included all the present area of Groton and Ayer,large parts of Dunstable and Littleton, almost all of Pepperell and Shirley, and other settlements as well.
In 1676 Indian tribes burned down all the buildings except for four garrisons. Survivors of the attack fled to the surrounding towns and returned a couple of years later.
As of the census 2000, there were 9,547 residents in Groton. This included 3,268 households and 2,568 families. The population density of the town was 291.3 people per square mile.
The population was spread out with 23.6% under the age of 18, 4.2% between ages 18 and 24, 32.7% between ages 24 and 44, 23.5% between the ages of 45 and 64, and 7% at the age of 65 or older. 36 was the median age of Groton in 2000.
As far as the income statistics are concerned, the median household income was $118,041, and the median family income was $136,653. The per capita income of Groton was $44,756. Approximately 1.8% of the population was under the poverty line.
Like most of the towns in New England, Groton is operated by an open Town Meeting, and administered by a selected Board of Selectmen and a Town Manager.
The Groton-Dunstable Regional School District operates schools in the region. There is one early childhood school, the Boutwell School; Two elementary schools: Florence Roche and Prescottelementaryschools; a middle school: Groton-Dunstable Regional Middle School; and a highschool: Groton-DunstableRegionalHighSchool.
This method is cumbersome, however, and is not used. As has already been pointed out the moment of resistance equals the total tension times the lever arm of the resisting couple; or BM=MR= T.a=f.A5.a using the notation already familiar. The arm, a, varies so little for varying tension steel areas that it may be assumed constant without serious error. With this assumption it becomes possible to lay down the principle that the area of steel required varies directly with the bending moment and the same curve by proper choice of scale mar serve both as moment curve and area-required curve. Usually practical considerations as to commercial size of bars result in the maximum area furnished being larger than that required. It is common to neglect this difference and compute bar lengths as though the maximum area furnished equaled that required. This reinforced concrete beam (Fig. 24) carries a uniform load. What are the minimum possible values of the dimensions a and b. The bending moment curve for this loading is a parabola with maximum ordinate at the center and the area-required curve accordingly is the same. The parabola of Fig. 24b is drawn with the center ordinate representing 6 sq. in. One bar may be bent up when 5 sq. in. only are required; so a = 9'4 = 3.7 ft. Similarly a + b = 9v' = 6.4 ft.
Shearing Stresses in Homogeneous Concrete Beams
A brief review of the shearing stresses in homogeneous beams is desirable in order that a clear picture may be obtained of the web stresses in beams of all kinds. For rigorous demonstration of these matters the reader should consult the standard treatises on the strength of materials are equal. Knowledge of the variation of horizontal shear intensity, therefore, gives also that of vertical shear. In Fig. 25b is shown a portion of a rectangular beam lying between any two sections, AA' and BB'. The variation of normal tension intensity at each section is indicated by the partial stress diagrams, the abscissas on AA' being shown larger than those on BB' on the assumption that the moment at AA', is the larger. Considering the stability of the small piece of beam cdBA, the pull on the cA face is larger than that on the dB face and the only force available to balance the difference is the horizontal shear on the plane ed. A brief consideration of the problem shows that the nearer the cd plane is to the neutral plane ab, the larger is the difference between the two tensions, and the larger the horizontal shear. Therefore the horizontal shear, and accordingly also the vertical shear, increase in intensity at a decreasing rate from zero at the extreme fiber to a maximum at the neutral plane. For a rectangular section the law of this variation is a parabola (Fig. 25a) with a maximum intensity of 317. The resultant intensity of stress at any point away from the extreme fibers, as, for example, on the vertical faces of the elementary prisms 1 and 2, Fig. 25a, must be inclined in direction, acting somewhat as shown. Referring again to the elementary prism shown, the shearing forces there shown may be resolved into components along the diagonals, and these components may be combined to give inclined tensile and compressive forces acting at 45 degrees (Fig. 25d) with an intensity (v) equal to that of the shear. This illustrates the case when the prism lies at the neutral plane where there is no direct stress. When it lies in the face of the beam there are no horizontal nor vertical shearing stresses and the resultant tension is horizontal, being that given by the usual formula for fiber stress. A more detailed study of the state of stress at any point in this cross-section would show that passing through it are two inclined planes, 90 degrees apart, on which there is no shear, the resultant stress being compression on one and tension on the other, of intensity greater than on any other plane through the point. These stresses are called the principal stresses at the point. Midway between these planes are those of maximum shear intensity. In the web of a plate girder the action of the inclined tension is easily resisted by the steel but the diagonal compression tends to cause buckling and it is necessary to limit the minimum thickness of the web or to provide suitably spaced stiffeners, or both. In a concrete beam, on the other hand, the material easily resists the diagonal compression but is weak in tension. The wooden beam resists both.
Cutting and/or enlarging door, window and bulkhead openings in concrete foundations.
Cutting 1" to 24" diameter perfectly round core holes for electrical, plumbing or vents in concrete floors and foundations.
Cutting and dicing concrete floors, concrete walkways, concrete patios or concrete pool decks for easy removal and/or neat patching.
Cutting trenches in concrete floors for plumbing, electrical, sump pumps, French drains or other utilities.
We cut and remove concrete, stone or masonry walls, floors, walkways, patios and stairs.