Bi-Directional Static Load Testing

Jorj Osterberg patented a load testing device and method over 35 years ago. A Florida company was created specifically to develop the technology and market it. Loadtest, Inc. was born in 1991. In 2009, Fugro acquired Loadtest and continued to develop the market. By then and despite patents, international competition became fierce in Indonesia, China, Singapore, India and Europe. In the United States, the patent expired in 2015 and three new companies offered BDSLT service in the United States. By 2026 it is estimated over twelve companies offer some version of BDSLT world-wide.

Often just called BDSLT, the test method has been around since the late 80's. An ASTM Standard (D8169) was created and published in 2018 and is widely referred to in most modern project specifications. The Standard was an adaptation of the first Deep Foundation Static Load Test Standard, ASTM D1143, first published in 1950. It describes the similarities of the older Standard but incorporated the differences unique to Bi-directional load testing. The test method has become the premier test used to determine or verify the load capacity of deep foundation elements around the world. Many contractors now prefer the simplicity of the test to more complex and expensive large reaction systems needed for top down tests. This is common to loads as low as 400 kips.

ASTM Standard D8169

About

The purpose of this site is to share knowledge about BDSLT and to answer questions.

Bi-directional testing has been around 35 years. In that time a lot has been learned. Engineers have learned a great deal about foundation construction as well. We invite contractors to share with us anything useful they learned about using BDSLT or about the methods that increase the odds of success.

With some of us getting over 30 years of experience in this industry, there are stories and lessons learned. In the 90's most contractors were nervous about BDSLT. Having an engineer specify the test was never great news. But a few stepped forward realizing the challenge was good for them and the deep foundation industry. Some also knew greater quality was important and this testing would help. They were right.

Become a BDSLT Expert

Our primary goal and passion is to help contractors and engineers understand static load testing and BDSLT. Knowledge is power. We believe in sharing the experience decades have provided.