Masonry infilled reinforced concrete frames have never been widely used in the U.K. for resisting lateral loading on buildings. Included amongst the reasons for this is the problem of the effect of creep in the columns of the frame on the vertical loading acting on the infill. When the columns of a masonry infilled reinforced concrete frame are subjected to long term deadweight loading, creep in the columns can result in significant vertical load transfer onto the infill. The degree of load transfer can not be accurately predicted and will vary with the age of the structure. It would therefore be desirable to avoid this load transfer entirely. This could largely be achieved if a layer of visco-elastic material with suitable properties were to be incorporated between the top of the infill and the bottom of the top beam. The basic requirements for the material being that it should behave elastically when subjected to short term racking wind or seismic loading whilst when subjected to long term loading, resulting from creep in the columns, it should itself creep so as to prevent significant vertical load transfer.

The results from short and long term tests on pre-loaded lead are presented and these indicate that this material should meet the above requirements. In addition the results from two half scale infilled frame tests are presented and compared. The two structures tested were similar except that only one included a layer of pre-loaded lead. The structures were first subjected to long term vertical loading and this was then followed by short term cyclic racking loading. The results indicate that the inclusion of a layer of pre-loaded lead into a masonry infilled reinforced concrete frame structure will reduce the vertical load transfer onto the infill if creep in the columns occurs, whilst not having any adverse effect on the performance of the structure when subjected to short term racking loading.

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