CE 427/527 – Temporary Construction Structures Homework #3 Due: Thursday, January 23, 2020 Topic: Equipment Loading; Formwork Loading and DesignFor this homework, it may be helpful to use MathCad or an Excel spreadsheet. Make sure you document all of your equations and show all work and calculations. Also, use the formwork design formulas discussed in class. 1. (10 points) An excavator will be located on a temporary work platform for excavating and lifting material on a project. Each track on the excavator is 16’-6” long (contact length) and 30 inches wide, and the tracks are located 9’-0” apart (center-to-center of the tracks). The operating weight of the excavator with a full load will be 88,000 lbs (centered at the midpoint of the tracks). During the operations, the maximum overturning moment is expected to be 123,000 lb-ft. The maximum allowable pressure beneath each track that can be sustained by the work platform is 5,000 psf. a. Calculate the eccentricity of the resultant force (e) based on the operating weight and overturning moment. Also, what is the shape of the pressure diagram, and is the length of the pressure diagram less than, equal to, or greater than the length of the tracks? b. Assume the excavator boom will be over the front of the excavator (parallel to the tracks): o Determine the maximum pressure beneath each track for the given overturning moment. Draw a sketch of the pressure diagram showing the magnitude and length of the pressure beneath each track. o Based on the maximum allowable pressure beneath each track (5,000 psf), what is the maximum overturning moment allowed during the excavator operation? c. Assume the excavator operator swings the boom such that it is over the side of the equipment (perpendicular to the tracks). o Determine the maximum pressure beneath each track. Draw sketches of the pressure diagram showing the magnitude and length of the pressure beneath each track. o Based on the maximum allowable pressure beneath each track (5,000 psf), what is the maximum overturning moment allowed during the excavator operation? o Assume one of the tracks is directly above and parallel to a support beam that is 25’-0” long. Draw separate sketches showing the loading (in plf) from the track on the beam for: (i) the location of the track that will create the greatest shear in the beam, and (ii) the location of the track that will create the greatest moment in the beam. 2. (10 points) A 7” thick lightweight concrete (105 pcf) elevated slab will be constructed in a building. The slab is 75 feet wide by 100 feet long. The wood formwork system used to cast the slab will consist of: 1” thick Class 1, B-B Plyform sheathing, 2x4 joists spaced at 12” on center, and 4x10 stringers spaced at 30” on center. The shoring to support the formwork will be 10’-0” long, 6x6 wood posts spaced in a 2'-6" x 5'-0”grid pattern. The lumber for the formwork and shoring will be Douglas-Fir Larch, Construction grade (S4S, density = 35 pcf). Assume a medium duty working surface. a. Determine the total vertical load (in psf) on the slab formwork. Include the weight of the concrete, self-weight of the formwork (excluding the shores), and personnel and equipment loading. b. Determine the horizontal construction load (CH, in plf) required by the ASCE 37-14 design loading manual to be applied along each edge of the slab formwork. Note: For this problem, exclude the weight of the shores. However, it would be conservative to include the weight of one half of the length of the shores. This assumes that the horizontal load associated with the weight of the lower half of the shores is directly resisted by the ground and only the weight of the upper half is included in CH.c. Does the loading calculated above meet the requirements for minimum horizontal construction load (CH) on slab formwork as prescribed in the ACI Formwork for Concrete book? d. Is the sheathing size sufficient to support the loading? Check bending, deflection, and rolling shear. Assume the face grain is parallel to the span. e. For the joist size and spacing given, is the stringer spacing adequate? Check bending, deflection, and shear. Assume the joist loading on the stringers is a line load (not individual point loads).