The seismic capability of Helifix remedial wall ties in cavity wall construction is being assessed at the University of Adelaide as part of an experimental study. Preliminary results indicate Helifix ties enabled a significant load transfer in tested wall specimens with an equivalent earthquake face loading acceleration capacity of well over 1g. This compares with the performance of conventional, new build small diameter metal ties that provided virtually zero load transfer across the cavity.

These tests follow a series of studies conducted over the course of the last few years by researchers at both the University of Auckland and University of Newcastle and during which time both the in-plane and out-of-plane seismic performance of masonry reinforced with HeliBar rods was investigated.

Testing of Helifix wall ties to Australian/New Zealand standard AS/NZS2699 also continues at the University of Newcastle. This standard classifies wall ties according to the design requirements outlined in Australian Standard AS3700, Masonry Structures, and NZS4210, Code of practice for masonry construction materials and workmanship. Testing has so far assessed the characteristic strength (Type A) and seismic resistance (Type B) of Helifix new build and remedial ties. New build cavity and veneer tie applications have been tested. A number of remedial scenarios demonstrating a range of Helifix drive-in, resin-based and combination installation techniques have also been assessed. Further Helifix remedial wall tie testing to AS/NZS2699 methodologies has been scheduled for 2012.

Cracks in masonry may lengthen, open and close as a result of numerous everyday factors, including on-going shrinkage and heave in foundation soils, and seasonal wet and dry, hot and cold environmental conditions. Under conditions such as these, Helifix Crack Stitching contributes improved masonry stability and the redistribution of tensile loads and wall movement to help minimise the chance of crack development. Under seismic conditions, Crack Stitching contributes further by adding strength to areas that might otherwise act as paths of least resistance. The system, which involves the bonding of HeliBar reinforcement into cut slots with HeliBond grout, has become an increasingly prevalent part of everyday life in Christchurch...Read more

Features and Benefits

• Suitable for all types of masonry including listed and historic structures and those with lime mortar
• Austenitic stainless steel reinforcing bars
• Fully concealed, non-disruptive repair system
• Cost-effective and more reliable than crack injection methods
• HeliBond is injectable and rapidly produces high compressive strength
• HeliBars and HeliBond grout produce excellent bond strength within the masonry
• HeliBars create great axial strength with flexibility
• No additional stresses are introduced
• Tensile loads are redistributed along the masonry
• Masonry remains flexible enough to accommodate natural building movement
• Minimises chances of the crack developing
• Reduces the likelihood of further cracking nearby
• Avoids any costly and disruptive taking down and rebuilding
• Permanent and sympathetic solution
• ...Read more

The rose window, organ, statues and pews of this modernist brick church in Wellington were removed in preparation for a substantial renovation and seismic retrofit project. Some interior walls were removed and a schedule of works designed to strengthen others was put into practice.

HeliBar installed at regular intervals into the internal brick wythes was specified for inclusion as part of the strengthening programme. A steel frame system was introduced to help distribute loads, with vertical elements connected to the existing brickwork. Slots were then cut into the intervening brick panels and HeliBar reinforcement bonded into position with HeliBond grout to provide additional flexural strength. Self-tapping stainless steel DryFix ties were then installed to help strengthen the connection between the internal and external brick leaves.

Thank you to all who attended sessions of our Masonry Repair and Seismic Upgrade Seminar.

Seminars were held in Chrischurch, Wellington and Auckland in May 2011 and were attended by engineers, architects, surveyors, contractors, building and construction agencies and laboratories.

Please Contact Us if you would like to receive copies of the reports mentioned in the seminars and have not already done so.

The reports include results presented by researchers at Auckland University and the University of Newcastle (Aus) as part of the Seismic Retrofit Solutions project, and recent tests into a variety of our different wall tie systems and installation techniques to Australian/New Zealand wall tie standard AS/NZS2699.

Helifix located its technical sales office and product warehouse in Christchurch following the September 2010 earthquake to ensure efficient and stable supply of materials to the earthquake recovery programme, and to allow product users and specifiers ready access our technical consultants.

Our office is open in Christchurch and committed to the rebuilding of the city and surrounding districts following the devastating February 22 event.

Helifix New Zealand services both the North and South Islands through this office, so please do not hesitate to Contact Us with any questions or to place an order.

All products are available for delivery direct to your site, office or home by express courier.

In the USA...

Following identification of wall tie failure, due to water ingress and corrosion, over 43,000 DryFix retrofit ties have been installed on the Robert A Young Federal Building in St Louis, Missouri...Read more

More from around the globe...

Helifix has delivered innovative repair solutions to the construction industry for over 25 years worldwide. Our materials and repair strategies have been used for masonry repairs undertaken in all types of buildings from the Opera House in Sydney, to the Musesum of Natural History in London, to the historic Fairmont Hotel in San Francisco, to the 650 year old Bouzov Castle in the Czech Republic.

Visit Helifix (Australia) Pty Ltd for details of selected projects conducted accross the Tasman or Helifix Ltd in the UK to download a copy of the latest UK HeliNews newsletter and for further details of Helifix projects conducted worldwide.