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Unformatted text preview: GUT Student Number Surname Given Name/s Examination Paper SEMESTER: SECOND SEMESTER EXAMINATIONS 2004 UNIT: CEB413 STRUCTURAL ENGINEERING 3  THEORY 1 DURATION OF EXAMINATION: PERUSAL: 10 MINUTES
WORKING: 3 HOURS
EXAMINATION MATERIAL SUPPLIED BY THE UNIVERSITY: EXAMINATION BOOKLETS EXAMINATION MATERIAL SUPPLIED BY THE STUDENT: WRITING IMPLEMENTS CALCULATORS — ANY TYPE AUSTRALIAN STANDARD A81170 OR H822
(THIS MATERIAL MAY BE ANNOTATED) INSTRUCTIONS TO STUDENTS: Students are prohibited from having mobile phones or any other device capable of communicating information
(either verbal or written) in their possession during the examination NOTES MAY BE MADE ONLYON THE EXAMINATION PAPER DURING PERUSAL TIME
ALL SIX (6) QUESTIONS ARE TO BE ATTEMPTED MARKS FOR EACH QUESTION ARE AS INDICATED THIS EXAMINATION PAPER MUST NOT BE REMOVED FROM THE EXAMINATION ROOM Queensland University of Technology
6101' Kelvin Grove W Carseldine 1 SCHOOL OF CIVIL ENGINEERING
QUEENSLAND UNIVERSITY OF TECHNOLOGY CEB413 STRUCTURAL ENGINEERING III
November 2004  Time: 3 Hours Closed Book Examination.
Students can bring the Australian Standard ASll70 or HB2.2 and can use any calculator QUESTION 1a. DIRECT STIFFNESS METHOD & COMPUTER ANALYSIS The structure shown in Figure la is to be analysed by the direct stiffness method, using all the
degrees of freedom. In order to demonstrate your understanding of the computer based process: a. Number suitably and indicate the active and restrained degrees of freedom.
b. Equate the given structure to the restrained structure and the structure to be analysed.
c. Determine the load vector {Q} and the displacement vector {D}, suitably partitioned. d. Write down the equations for transforming the member stiffness matrices from the local to the
global system and indicate the “G” for each transformation. 6. Indicate the global degrees of freedom in each of the transformed member stiffness matrices. (8 marks) ‘
MWWWWW CEB413TI.042 2 QUESTION 1b  STIFFNESS METHOD  APPROXIMATE SOLUTION For an approximate analysis by hand calculation, consider only the rotational (ﬂexural) degrees of freedom and analyse the structure in Figure 1.b by the stiffness method and draw the bending
moment diagram. EI= constant for all members. (10 marks) W= 40kN/m
W= 20kN/m Figure 1.b Cont/. .. CEB413T1.042 QUESTION 2 APPROXIMATE METHODS Use approximate methods (highrise / cantilever method) to determine the bending moments and the proportion of shear taken by each columns in the top ﬂoor of the structure shown in Figure 2. (Area
constant for all columns) (14marks)
15 kN ————>
30 kN ———+
30 kN ——————+
5 @ 6m Figure 2 Cont/... CEB413T1.042 QUESTION 3a LOAD PATHS/BRIDGES Sketch the load path in the pile cap shown in Figure 3.a. Based on the load path, design the tensile
reinforcement required in the base of the pile cap. (4 marks) DL =2000 kN
LL = 500kN Pile Cap d = 950mm 1500mm Figure 3.a Cont/... CEB413T1.042 QUESTION 3b — BRIDGES/LOAD PATHS a. List three factors that should be considered when beginning the design process for bridges. b. The bridge shown below in Figure 3.b is a cablestayed ~trussed, pedestrian bridge spanning a
canal. The bridge has been designed to rotate to one side to allow large vessels to pass through
the canal. Thus the bridge has two major design load cases i. dead and live loading in its normal position,
ii. dead load while the bridge is rotating to its stowed position and is acting as a cantilever. Sketch the load paths for the bridge for each of the above cases. (10 marks) VAVAVAVAVAVAVAVA‘ Elevation Bridge Cantilevers across canal as
it moves to the stowed position Normal operating position Figure 3.b Cont/... CEB413T1.042 6 QUESTION 4. STRUCTURAL DYNAMICS & VIBRATION a. A structure modelled as a single degree of freedom system has a circular natural frequency of
vibration co_= 6 rad/sec and is attached to a machine having a circular frequency of Q = 3 rad/sec.
Determine the dynamic ampliﬁcation in the response. (2 marks) b. Describe, using sketches, how the period (or frequency) of Vibration is used in the analysis and
design of a bridge. (3 marks) c. The frame shown in Figure 4 has rigid ﬂoors and can be considered as a “shear frame”. The
masses are lumped onto the ﬂoor slabs as shown in the Figure. Determine (i) the structure stiffness matrix (ii) the structure mass matrix and (iii) the natural periods of Vibration and the
associated mode shapes for this structure. The mode shapes should be plotted with respect to
a vertical axis. Assume EI/mL3 =2.5. (12 marks) Figure 4 Cont/. .. CEB413T1.042 7 QUESTION 5. PLASTIC ANALYSIS & COLLAPSE MECHANISMS Using appropriate sketches, explain what you understand by (a) a plastic hinge and (b) collapse
mechanism. (5 marks) The frame shown in Figure 5 has to support the service loads shown, with Mp = lSOkNm. It has 2
independent collapse mechanisms, viz; the beam and the sway. Investigate these two and the combined mechanism and determine the critical collapse mechanism and the collapse load factor 9».
Draw the bending moment diagram associated with the critical mechanism. (12 marks) a) = no XN/m 1‘ Figure 5 Cont/. .. CEB413T1.042 8 QUESTION 6. — EARTHQUAKE ENGINEERING a. Reference is made to the fundamental period of vibration T1 of a building in seismic analysis by
the QuasiStatic Method in ASl 170.4. Explain, (using sketches, if necessary), the role of T1 in
this method. (3marks) b. Brieﬂy explain how asymmetry affects the seismic response of a structure
(4 marks) c. A seven storey building, with a storey height of 3.5m (and total height 245m), used as an
apartment block for service personnel in Newcastle, has a rectangular plan with dimensions 48m
x 32m. Live load on all the ﬂoors, including the roof, is to be taken as 8 kN/mz, with a live load reduction factor w = 0.4. Dead load on all the ﬂoors, except the roof level, is 10 kN/mz, while
dead load on the roof slab is 6kN/m2. Determine the total base shear force V for a quasistatic earthquake analysis. Determine also the
distribution of shear forces across the height of the building and plot their variation with height. The
earthquake acts in the direction normal to the longer dimension. With the usual notations you may
assume, Rf: 4, I = 1.25, S = 1.5 and a = 0.11 Wewcastle). (13 marks) END OF PAPER CEB4l3Tl.O42 ...
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