3. Give an example of a real component or structure in which fatigue is an important factor to consider during design. (2 points) 4. From the answer to problem 3, if your design were not economically limited, what factor that affects fatigue resistance, would you be willing to reinforce for the integral good of the part? (4 points) Prepare your answer judiciously.

An RO facility is being designed to treat groundwater containing
the ions given below. Calculate the allowable recovery before scaling
occurs and identify the limiting salt. Assume 100 percent rejection, a
concentration polarization factor of 1.08, and T = 25◦C, and ignore
the impact of ionic strength. The water contains calcium = 105
mg/L, strontium = 2.5 mg/L, barium = 0.0018 mg/L, sulfate = 128
mg/L, fluoride = 1.3 mg/L, and silica = 9.1 mg/L as Si.

1. Use Figure 1 and Table 1 for the following:
   1. Compute the vertical effective stress (σ'_v) in kN/m² at the center of the clay layer prior to the construction of the footing.
   2. Assuming a load of 1150 kN, use the Boussinesq procedure to determine increase in the vertical stress (Δσ) in kN/m² at the center of the clay layer below the center of the footing.
   3. Assuming the values that you computed in (a) and (b) are representative for the entire thickness of the clay layer, calculate the ultimate primary consolidation settlement (ΔH_final) in mm that will occur in the clay layer from placement of the footing. Use an empirical relation to estimate the compression index.
   4. A consolidation test was performed on a 25 mm thick, undisturbed sample taken from the center of the clay layer. The time and dial gauge readings obtained from an increase in pressure on the specimen from 200 to 400 kN/m² are given in Table 1. Use the "logarithm of time" method (i.e., Casagrande procedure) to determine the coefficient of consolidation (c_v) in mm²/min.
   5. Using Terzaghi's 1D consolidation theorem, calculate and plot the predicted settlement of the footing as a function of time (i.e., ΔH(t) vs. time), where ΔH(t) is in mm and time is in days. [Compute ΔH(t) at enough times so that you can reasonably construct the requested plot. Also, compute ΔH(t) for times long enough that ΔH_finalis reached.]
   6. Based on the inherent assumptions in Terzaghi's 1D consolidation theorem and those made above versus actual field conditions, would you expect the footing in Figure 1 to settle faster or slower than predicted in (e), why?

   7. Time (t) from the application of pressure increment (min)	Dial gauge reading (mm)
      0	4.995
      0.1	5.010
      0.25	5.033
      0.5	5.053
      1	5.107
      2	5.153
      4	5.211
      8	5.287
      15	5.351
      30	5.379
      60	5.400
      120	5.418
      290	5.434
      395	5.440
      1230	5.460

      Table 1. Time vs. deformation readings for a stress increase from 200 to 400 N/m².

For an intersection with signal control, explain what’s included in the total lost time and the reasons.

[HCM for Basic Freeway Segments] A four-lane freeway (two lanes in each direction) has an observed demand volume of 2400 veh/h (one direction) during the peak hour. The freeway is on rolling terrain and the traffic stream consists of passenger cars and trucks only. The peak-hour factor is 0.75 and the traffic is all commuters. If the peak 15-min demand flow rate under equivalent base conditions is estimated to be 2000 pc/h/ln, what is the percentage of trucks in this traffic stream?

Explain why the UU triaxial shear test would be the most appropriate test for simulating the strength of clay below an embankment at the end-of-construction.

A 3 diameter biotower has been designed to treat sewage from 22,000 PE.Influent BOD = 250mg/l and wastewater flow through the primary clarifier removes 35 percent of the BOD and the flows into the biotower the constant r andom media n= 0.44, recycle ratio = 2 and operating temperature =250^0c.

a determine the reaction rate constant k₂₅ if the existing BOD =50mg/l

b what would be the biotower effluent at 20^0c if the recycle ratio is increase to 4

What five items should be tracked or monitored and calculated on the submittal log?

Derive an expression for the factor of safety against slope instability for an infinite slope at an angle ?? from horizontal, and with horizontal groundwater seepage emerging from the slope (and then running off). The soil has a total unit weight ?? and the strength is defined by ??′ and ??′. Assume drained conditions. Define the potential failure plane as being located a distance “??” from the slope surface measured vertically.

Blocks A and B have a masses of 200 kgkg and 250 kgkg , respectively.(Figure 2) The coefficient of static friction between A and B and between B and C is 0.210. The coefficient of static friction between the rope and peg E is 0.520. Pulley D rotates freely, and PPP_2 = 26.0 NN . If θθtheta_2 = 60.0 degreesdegrees , what is the smallest magnitude, TTT, of tension, TTT_evec, that causes block B to move?

Design a staircase for a two story building with the given loads DL = 72 psf and LL= 60 psf. The staircase design must comply with A.D.A. requirements for hospital buildings.

1. With respect to the polymerization process, what is the primary difference
between a thermoplastic polymer and a thermoset polymer? How does this affect recycling?

2. In a typical stress-strain plot of a structural steel, why is the apparent drop-off
in strength after reaching the ultimate value not a realistic portrayal of steel behaviour? Why is
this phenomenon ignored in steel structure design?