8. ARCHTEC STRENGTHENED ARCHES - COMPARISON OF TEST AND PREDICTED RESULTS

8.1 Archtec Test 1

Figure 8.1 compares the load versus displacement results obtained by ELFEN with those obtained from the first Archtec test(20) and also with the comparable unstrengthened ring separated arch. Failure loads are summarised in Table 8.1 and ELFEN contoured results at failure, including strengthening reinforcement stresses, are given in Figure C.1 in Appendix C.

Predictions made with ELFEN are almost exact with the failure load within 2% of test result and with very good stiffness correlation, displacements remaining within approximately 5% of test values, throughout the loading stage.

The composite behaviour of the Cintec anchors behaving as embedded reinforcement with the barrel masonry cannot be represented with the conventional analysis programs and so no comparable results can be provided.

Figure 8.1 5m Span Archtec Test 1 – Comparison of Predicted and Test Results
Separated Brick Rings
Load versus vertical displacement under the line load

Making comparisons between the two tests, strengthened versus unstrengthened, TRL was able to make the following principal conclusions:

1. The failure load of the strengthened arch barrel has been increased by a factor of 2.05.
2. The first -installed anchors delayed the formation of hinges
3. The anchors added considerable strength to the arch barrel
4. The arch failed in a gradual and a ductile manner

Table 8.1 Summary of Test and Predicted Failure Loads

8.2 Archtec Test 2

Figure 8.2 compares the load versus displacement results obtained by ELFEN with those obtained from the second Archtec test(21) and also with the comparable unstrengthened ring separated arch. Again, failure loads are summarised in Table 8.2 and ELFEN contoured results at failure, including strengthening reinforcement stresses, are given in Figure C.2 in Appendix C.

Figure 8.2 5m Span Archtec Test 2 – Comparison of Predicted and Test Results
Separated Brick Rings
Load versus vertical displacement under the line load

Predictions made with ELFEN are almost exact and with the failure load within 1% of test result and with very good stiffness correlation. Ignoring a short period of unloading, calculated displacements remained within approximately 5% of test values throughout the loading stage.

Apart from confirming the findings of the first Archtec test the TRL were able to draw the following new principal conclusions:

1. The failure load of the strengthened arch barrel has been increased by a factor of 2.24.
2. The behaviour of the Multibar anchor is similar to the Standard Cintec anchor tested previously.

Table 8.2 Summary of Test and Predicted Failure Loads