联系我们： 手动添加方式: 微信>添加朋友>企业微信联系人>13262280223 或者 QQ: 1483266981

ENG3014
UNIVERSITY OF EXETER
FACULTY OF ENVIRONMENT, SCIENCE AND
ECONOMY
DEPARTMENT OF ENGINEERING
January 2023
Structural Engineering
Module Convenor: Dr M. K. Wadee
Duration: TWO HOURS + 30 minutes upload time
No word count
Answer BOTH questions
Materials to be supplied:
Graph paper
This is an OPEN BOOK examination.
ENG3014 1 CONTINUE
Question 1 (50 marks)
(a) Explain the reasons for there to be more than one limit state in modern structural
engineering design codes. (10 marks)
(b) A three-spans bridge with spans each of length 8 m is to be designed as a contin_xfffe_uous beam. The supports A, B, C and D are simple. The structure has the same
section properties throughout. The action under consideration is a single downward
point force with a factored total magnitude of 80 kN. Assuming that the critical sec tions for the structure are at the centres of each span and the internal supports B
and C, determine, using the concepts of influence lines, or otherwise, the maximum
elastic sagging bending moment at each of those locations. (15 marks)
(c) A plate girder is required to span 18 m as a fixed-end beam and to carry a total ac tion (including partial factors on actions) of 30 kN m 1
acting over the whole span.
Design a basic steel section assuming that the compression flange is adequately
restrained against buckling and using grade S275 steel. Clearly state any assump tions that you make. (25 marks)
ENG3014 2 CONTINUE
Question 2 (50 marks)
(a) Describe the various mechanisms that contribute to resisting shear forces within a
reinforced concrete beam. Explain the inherent assumptions when evaluating the
shear capacity of a reinforced concrete beam using the variable strut inclination
method. (8 marks)
(b) Consider the design of a reinforced concrete beam having length and support con ditions as shown in Figure Q2. The beam is to carry unfactored permanent actions
(including self-weight) of Gk kN m 1 and unfactored variable action of Qk kN m 1
.
A rectangular section of width 320 mm and depth 500 mm is considered for the
design. A concrete cover of 30 mm is required. Answer the following questions on
the design of the beam. Use partial safety factors for actions and materials as ap propriate. Assume characteristic yield strength of reinforcing steel as 500 N mm 2
and elastic modulus of steel as 200 kN mm 2
.
i. Determine the critical sections along the length of the beam for flexural design
at ULS. Illustrate using diagrams the load cases that will determine the bending
moments at these sections in terms of Gk and Qk. (8 marks)
ii. Assume that the longitudinal steel reinforcement consists of 4 steel bars of 25
mm diameter in tensile zone at an effective depth of 440 mm and 2 steel bars
of 10 mm diameter at an effective depth of 50 mm. Determine the minimum
characteristic cylinder strength fck of concrete required to ensure the section
behaves as an under-reinforced section at ULS. (10 marks)
iii. If the characteristic cylinder strength fck of the concrete is 30 N mm 2
, design
suitable longitudinal reinforcement for the beam section at support A to resist
a maximum hogging bending moment of 480 kN m at ULS. You may use rein forcement in both compressive and tensile sides, as appropriate. (16 marks)
iv. Assume that shear reinforcement is provided in the form of two legs of 12 mm
diameter stirrups at 90 mm spacing at support C. Also assume that the char acteristic cylinder strength of the concrete fck is 30 N mm 2
and the effective
depth of longitudinal tensile steel is 440 mm. Determine the maximum shear
force that the beam can support at this section at the ultimate limit state using
the variable strut inclination method. Also determine the minimum area of longi tudinal tensile steel required at this section to support this shear force.(8 marks)
C A
B
Figure Q2: Beam for Question 2
END OF QUESTION PAPER
ENG3014 3