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Extensive earthquake dynamic fitness test

1. Preface

One of the most used arguments for plastic pipe systems is the flexibility and durability. If a question appears about earthquake fitness, the plastic pipe industry normally replies by showing damage-statistics. And indeed, the statistic results are very convincing, especially with damage statistics of rigid pipe systems. In the last editions of our IMPROFIL magazine we published many reports regarding earthquakes (mainly from our friends in Japan)- but a practical orientated dynamic test of a complete plastic pipe system with all aspects of different jointing methods, fittings and constructions has never been done before.

Seismic regionalization of Russian FederationPicture 1: Seismic regionalization of Russian Federation

Thanks to the initiative of Krah Pipes Estonia, the well-known Russian JSC Research Center of Construction in Moscow has performed an extensive test program to investigate the earthquake fitness of the full Krah Pipe System with seismic intensity of 7-9 magnitudes. For the complete technical report please contact the management of Krah Pipes Germany directly (email: This email address is being protected from spambots. You need JavaScript enabled to view it.).
Below please find the summarized technical report with the original title:

“Conduction of dynamic tests of conduits system including pipes, fittings, containers, wells, and pump stations of trade mark “KRAH PIPES” with assessment of the opportunity of their application in the regions of Russian Federation with seismic intensity 7-9 magnitudes”.

2. Introduction

The technical report is using the results of experimental researches of polyethylene conduit elements of the trade mark “KRAH PIPES”, designed for outdoor sewerage, disposal of waste water and ventilation. The tests were conducted on the stand which was specially designed by JSC Research Center of Construction, Research Institute of Building Constructions. The stand is a pendulum-type platform vibrator.

The purpose of the laboratory tests is estimation of workability and exploitative reliability of polyethylene pipe conduit elements in seismic regions of Russian Federation with 7÷9 degrees of intensity according to the MSK-64 scale.

The report is issued in accordance with the requirements of existing regulations. The terms and definitions from SNIP II-7-81* were used for describing methods and results of seismic stability experimental researches of polyethylene pipe conduit elements for outdoor sewerage, disposal of waste water and ventilation.

Worldwide the risk of earth quakes is a big issue, the population in the “red” areas is high and so the infrastructure is a critical point.

Worldwide high seismic regionsPicture 2: Worldwide high seismic regions

3. Test setup

A Krah Pipe system is assembled by using typical jointing procedures:

  1. Electrofusion 
  2. Extrusion Welding
  3. Rubber gasket

The pipe system is installed as a loop, including different pipe diameters between DN/ID 300 and DN/ID 500 mm, different kinds of fittings like bends and reducers and also a manhole-shaft. For the pipes, fittings, bends and manholes typical profiled wall structure is used. The complete setup is filled with water.

Everything is installed on a vibration platform, designed for the simulation of earthquake loads under consideration of typical accelerations and amplitudes.

Test set-upPicture 3: Test set-up

The vibration tests were conducted in the day time at an air temperature lower than +15˙C. During the tests the vibration platform acceleration, by the data of accelerometers which were installed on the platform, was changed in intervals from 1.04 to 8.36 m/s2. Oscillation frequencies of the system were changed in intervals from 1.0 to 11.4 Hz, the oscillation amplitudes were changed in intervals from 0.7 to 33.2 mm.

4. Test program and test procedure

  1. The dynamic tests program of the conduit elements of the trade mark “KRAH PIPES” on the vibration platform includes the following:
    The tests of water-filled conduits are conducted with the change of frequency spectrum from 0 to 15 Hertz with the fixed displacement amplitude of the vibration platform. Then the value of amplitude changes and the frequencies are set in the specified spectrum. The duration of all the specified dynamic loadings (with the fixed amplitude and frequency) is approximately 30 seconds.
  2. By the tests results the levels of impacts are set corresponding to the resonance oscillation of the system and the accelerations levels of the vibration platform correspond to 7÷9 magnitude by the MSK-64 scale.
  3. When the tests are performed the repeated tests with combinations of amplitude frequency parameters corresponding to the resonance oscillation of the system and 7÷9 magnitude impacts are conducted in accordance with testing program of measuring of amplitude frequency spectrum of the vibration platform.

5. Conclusions and recommendations

On the basis of dynamic tests results analysis of conduit elements of trade mark ‘’KRAH PIPES” it may be noted that:

  1. In accordance with the program of experimental researches on the vibration platform of Research Institute of Building Constructions the dynamic tests of polyethylene elements of conduit made by ТУ 2248-001-30233670-2011 and ТУ 4859-002-30233670-2011. During the tests dynamic loads corresponding to 7÷9 magnitudes were simulated. The fragment of pipeline during the tests was filled with water.
  2. During the tests the vibration platform acceleration, by the data of accelerometers which were installed on the platform, was changed in intervals from 1.04 to 8.36 m/s2 what exceed the value of acceleration corresponding to earthquake action 9 magnitudes. (4 m/s2)
  3. During the tests when the values of natural oscillations frequencies of conduit coincided with the oscillation frequencies of the vibration platform, the resonance occurred. This phenomenon was observed when the system oscillated with the frequency f = 10.4 Hz. At the resonance the maintenance reliability was not broken.
  4. Polyethylene elements of pipe line system of trade mark ‘’KRAH PIPES” incudes the pipe with the next types of connection: electrofusion, connection with the help of the rubber gasket, connection with the help of the hand extruder, and also pipe fittings, reservoirs, wells, and pump stations which are recommended for application in Russian Federation in regions with seismic intensity of 7÷9 magnitudes.

Examplary Accelerograms (m/s2) and spectrums of the maximum value of amplitudes (mm),
recorded by installed sensors:

accelerogram 1Picture 4: Accelerograms (m/s2) recorded from installed sensors
The test mode #9 (frequency f = 1.3 Hz; amplitude A = 16.4 mm)

 accelerogram 2

Picture 5: Spectrums of the maximum value of amplitudes (mm) for installed sensors.
The test mode #25 (frequency f = 10.4 Hz; amplitude A = 0.9 mm)

The complete report (90 pages) and videos are available, just send a request to This email address is being protected from spambots. You need JavaScript enabled to view it..

KRAH PIPES GmbH & Co. KG
Betzdorfer Str. 8
D-57520 Schutzbach
Germany