Column splices ends prepared for contact in bearing Fig
25 Column splice ends prepared for contact in bearing Splices should be designed for full contact bearing to resist the vertical loads. In addition, the following recommendations should be followed a the projection of the flange cover plates beyond the ends of the column members should be equal to the width of the flange of the upper column or 225 mm, whichever is greater b the thickness of the flange cover plates should be half the thickness of the flange of the upper column or 10 mm,...
Design procedure
a Calculate the factored load 1.6 x imposed 1.4 x dead, and then calculate the maximum factored bending moments Mx and the factored shear forces b Calculate the second moment of area required to satisfy the deflection limitations described in clause 2.6.2. For simply supported beams, use the method described in clause 4.2 b . c Determine the effective length LE from the two cases Beams with lateral restraints at their ends only The effective length LE should be obtained from Table 7 according...
Butt welds
Throat thickness for full penetration welds should be taken as the thickness of member. For partial penetration welds, it should be taken as the minimum depth of weld penetration, except that it should be taken as the actual depth less 3mm for V- or bevel welds. The depth should not be less than 2 f t, where t is the thickness in mm of the thinner connected part. The design strength should be taken as that of the parent metal, provided that the weld is made with a suitable electrode. Any...
Design strength py
This Manual covers the design of structures fabricated from steels supplied to BS 4360, and the design strengths, py, should be obtained from Table 2. Other steels may be used provided that their design strengths are obtained in a similar manner as in BS 4360.
Top and bottom cleats Fig
a Choose size of seating cleat angles b Calculate the number of bolts required in shear and bearing on the lower cleat, which is assumed to support the whole of the vertical loading c Alternatively, calculate the weld size to suit maximum length available d Check buckling strength of beam web e Check bearing strength at the root of the beam web f Check bearing strength of angle cleat area of bearing x design strength g Check bearing strength of column due to bolt loads where appropriate....
Web buckling and bearing
This check should be carried out when heavy loads or reactions are applied to unstiffened webs, e.g. it applies to beams supported on the bottom flange with the load applied to the top flange to a column supported by a beam to a beam continuous over a column and to web resisting compression forces from haunches in portals. Web buckling and bearing may be checked as described below, the dimensions being shown in Fig. 29. where Z gt , is the length of stiff bearing is as shown on Fig. 29 t is the...
Lattice girders or trusses
These members should be designed using the following criteria a connections between web and chord members may be assumed to be pinned for calculation of axial forces in the members b members meeting at a node should be arranged so that their centroidal axis or lines of bolt groups coincide. When this is not possible the members should be designed to resist the resulting bending moments caused by the eccentricities of connections in addition to the axial forces Similarly, bending moments arising...
Uncased columns
This Section describes the design of uncased columns for braced multistorey construction which are subject to compression and bending. Two cases are considered Case I columns braced in both directions and subject only to nominal moments Case II columns braced in both directions and subject to applied moments other than nominal moments. For both of these cases an iterative process is used requiring selection and subsequent checking of a trial section. The first step is to determine the effective...
Rafter stability
The rafter should be checked to see that stability is maintained in all load cases. Unless there is wind uplift, the following checks should be made a the plastic hinge location as obtained in subsection 11.6 near the ridge should be restrained for the case of a uniform load b a purlin or other restraint is needed on the compression flange at a distance Lm calculated from the plastic hinge restraint formula given in clause 11.7.1 c further restraints to the top flange are required so that the...
Design procedure Dht
The procedure to be adopted is set out below, and the various dimensions are shown on Fig. 12. a calculate the span height to eaves ratio L h b calculate the rise span ratio r L c calculate the total factored load WL on the frame from subsection 9.2, and then calculate WL2, where W is the load per unit length of span L e.g. W ws, where w is the total factored load per m2 and s is the bay spacing d from Fig. 13 obtain the horizontal force ratio Hm at the base from r L and L h e calculate the...
Stability of stanchion
Near the top of the stanchion a restraint should be provided at the location of the plastic hinge, together with a further restraint at a distance lm below the position of the hinge restraint. If the stanchion is restrained on the tension flange as described in subclause 11.7.3 d then the distance to the nearest restraint on the compression flange may be taken as lt as calculated for the stability of the haunch. The stanchion should then be checked in accordance with the overall buckling check...
Portal frame connections Portal frame haunch Fig
a Assume the number and type of bolts required at 1 and 2 see Fig. 27 to resist the factored bending moment, and locate them to obtain the maximum lever arm. b Using the force distribution shown in Fig. 19, calculate the resistance moment. If this is less than the applied moment increase the number and or size of bolts. c Check the thickness of the end plate required to resist the bending moments caused by the bolt tension. Double-curvature bending of the plates may be assumed since bolts...
Bracing
Choose the location and form of bracing in accordance with the recommendations in clauses 2.2.3 and 3.4 a . Typical locations are shown on Figs. 1 and 2 for different shaped buildings. The wind load or the notional horizontal forces on the structure, whichever are greater, should be assessed and divided into the number of bracing bays resisting the horizontal forces in each direction. Braced frame rectangular or square on plan Note that roof and floors will act as horizontal girders provided...