## Alternative design procedure for calculation of compressive resistance Pc for columns

As an alternative procedure to that described in subclause 5.4.1 (g) the compressive resistance Pc of a column may be obtained from where Ag is the gross sectional area of the trial section, and pc is the compressive strength. (a) choose a trial section avoiding slender UB sections and obtain the design strength py from Table 2 according to the thickness of the flanges and grade of steel of the chosen section (b) calculate the slenderness A by dividing the effective length LE obtained as in...

## Case I Columns braced in both directions simple construction

For simple multistorey construction braced in both directions the columns should be designed by applying nominal moments only at the beam-to-column connections. The following conditions should be met (a) columns should be effectively continuous at their splices (b) pattern loading may be ignored (c) all beams framing into the columns are assumed to be fully loaded (d) nominal moments are applied to the columns about the two axis (e) nominal moments may be proportioned between the length above...

## Condition I Full lateral restraint provided Design procedure

(a) Calculate the factored load 1.6 x imposed + 1.4 x dead, and then calculate the maximum factored bending moment (M), and the factored shear forces (b) Calculate the second moment of area (7) required to satisfy the deflection limitations described in clause 2.6.2. For simply supported beams where is the second moment of area required in cm4. W is the total unfactored imposed distributed or point load in kN L is the span in metres and C is the deflection coefficient obtained for each loading...

## 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 (I) 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 as described in clause 4.3 (c). (d) Choose a trial section and grade of steel and check that the equivalent uniform...

## Determination of effective length of columns

For braced multistorey buildings the columns are held in position, so that the effective length Le to be used in design depends on the degree of restraint in direction (i.e. rotational restraint) afforded by the beams attached to the columns at each floor level or the foundations. Fig. 4 illustrates typical joint and foundation restraint conditions. Substantial base provides restraint about both axes Restrained or partially restrained about both axis Substantial base provides restraint about...

## Portal frame ridge

Bolts at levels 1 and 2 resist moment Bolts at level 3 resist shear 28 Portal frame ridge (a) Assume the number and type of bolts required at 1 and 2 (see Fig. 28) to resist the bending moment and locate them to obtain maximum lever arm. (b) Using the distribution of force shown in Fig. 19, calculate the resisting moment. If it is less than the applied moment increase the number or size of bolts. (c) Check the thickness of end plates to resist bending moments caused by the bolt tension provide...

## Column splices ends prepared for contact in bearing

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,...

## Top and bottom cleats

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...

## Portal frame connections Portal frame haunch

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...