(Solved): 4. The two span highway bridge shown in Figure Q4 is a steel and concrete com ...

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4. The two span highway bridge shown in Figure Q4 is a steel and concrete composite multi-girder construction. The concrete deck is $$250\mathrm{mm}$$ thick (assume this thickness is uniform across the bridge), with concrete grade C35/45 and the steel is S355J2G3. (a) The central girders at the pier need to be designed for $$V_{Ed}(ULS)=250\mathrm{kN}$$ from permanent loading and $$V_{E_d}($$ ULS $$)=600\mathrm{kN}$$ from traffic loading. Assume the composite section is elastic, determine the value of longitudinal shear. The short-term modular ratio is $$6.0$$ and the long-term modular ratio is 16.7. The section properties are given in Table Q4.a below. For the calculation of effective area of concrete slab, assume $$b_0=400\mathrm{mm}$$. lable Q4.a [10 marks] Question 4 continues on the following page TURN OVER Page 6 of 13 Question 4 continued (b) For the central girders over the pier, the plastic distribution of longitudinal stresses is assumed to occur over a distance of a quarter of the equivalent span Le $${\mathrm{i}}_{\mathrm{i}}$$, shown in Figure Q4.b. Use the longitudinal shear calculated from Question 4(a), design a suitable shear connector arrangement using $$19\mathrm{mm}$$ diameter, $$140\mathrm{mm}$$ high shear studs. The ultimate tensile strength of the shear connectors should be taken as $$f_{\mathrm{U}}=450\mathrm{N}/{\mathrm{mm}}^2$$. Figure Q4.b [10 marks] (c) Each steel girder for the two span bridge will be fabricated in 3 sections and joined together on site during construction. Suggest a suitable type of connection and describe the design considerations for this joint connection.