The past two decades have seen virtually all engineering consultants embrace and move to detailed computational methods of analysis and CAD documentation. Indeed, engineering graduates of today may never have known life without a computer. For those of us old enough to remember the pre-spreadsheet days when calculations were carefully computed on handheld calculators and written up neatly on sketch pads, this issue of Structures and Buildings will be refreshing. All of the papers contained within it present simple hand methods that an engineer can use to quickly get a feel for the capacity of their structures without the need for a computer.
In today's design office there is often a temptation to launch into large detailed finite-element models. In the early stages of projects there may not be the time or budget for such complex analysis and so quick, simple and effective methods of hand calculation can be very useful in getting reliable answers in a short timeframe. They can also play a very important role in gross error checking and verifying large complex numerical models and their results.
In this issue we have three papers, two of which are by the same authors. All three papers contribute to the body of knowledge of their chosen topics by providing useful simple methods for assessing structural capacity.
The first paper in this issue is a briefing by Nicol-Smith (2012). He presents a simple design method for dowel fasteners. The method is an approximation and is more realistic for long embedment lengths, while greatly simplifying the design process. The effects of wood crushing and embedment length are accounted for. The method is applicable to bolts, lag screw connections and connections with griplam rivets.
The second paper by De Lorenzis et al. (2012a) is a structural study of masonry buttresses of trapezoidal form. It presents a brief history of the sizing of buttresses from La Hire in 1712 to Huerta on 2010. An analytical model for predicting the failure of trapezoidal buttresses is developed including overturning and fracture. Results are presented for various buttress geometric configurations and loading conditions and compared to numerical simulation model results. The comparison shows good correlation with the analytical method being slightly conservative due to the complex cracking patterns in the masonry observed in the numerical model.
The third paper, again by De Lorenzis et al. (2012b), extends the work from their first paper to develop an analytical method for masonry buttresses of the stepped form that includes sliding, overturning and fracture. Results are presented for various step arrangements and buttress geometric configurations and compared to numerical simulation results. Predictions of the analytical method compare well with the numerical method. The effect of buttress shape is discussed at length and a real example of a gothic buttress is presented.
