TUCSS Monthly Seminar No. 237 – Thursday, 18 August 2022, 6.30 pm
Role of Reinforcement in Tunnel Linings
by Dr. Ralf Winterberg, BarChip Inc., Group Chief Engineer
Concrete is the construction material of choice when speaking about tunnel linings. However, its inherent brittleness must be overcome to make it a ductile material. Reinforcement is required to bridge the tensile cracks and to provide robust, durable, and dependable behaviour. The purpose of the required reinforcement is usually to provide sufficient rotation capacity. Peak load or load-bearing capacity should normally not be related to the reinforcement. Value engineering can save significant costs related to reinforcement when the load-bearing system is well understood. Finding the right reinforcement for a structural load-bearing system will yield the most economical design.
This presentation investigates the performance of different tunnel lining systems and analyses the reinforcement requirements for their typical structural load-bearing systems. In most tunnel linings the presence of axial thrust contributes to significant flexural capacity. This is especially the case for segmental linings. Experimental investigations show that relatively low fibre dosages can provide hardening system behaviour yet at relatively small levels of axial thrust. Further, the application of design values obtained on standard beam tests significantly underestimates the performance of fibre reinforced concrete (FRC) in statically indeterminate elements or structures.
Similar conclusions can be drawn in fibre reinforced shotcrete linings where traditional peak load analysis produces highly conservative designs. Confinement leads to compressive arching action being the dominant parameter with lining thickness and matrix strength governing the load resistance, while the degree of reinforcement plays a subordinate role. Parallel to academic research, industry investigations are being undertaken to better understand this effect and to account for the beneficial influence of compressive membrane action on load resistance.
The results of the experimental testing program and the academic research demonstrate that in many cases engineered FRC can provide the required structural ductility, robustness and safety of tunnel linings while reducing construction cost and time.
Dr. Ralf Winterberg is specialised in fibre reinforcement for concrete and its application development. He graduated in Civil Engineering (MSc) at the University of Bochum, Germany, and received his PhD on the cracking behaviour of steel fibre reinforced concrete there in 1998. After several engagements with international steel fibre companies, he joined BarChip Inc. (formerly: Elasto Plastic Concrete) in July 2014, the market leaders in structural synthetic fibre reinforcement, to take up the role as Group Chief Engineer for their worldwide structure. With more than 25 years’ experience he is committed to further develop BarChip leadership as a technical solutions provider. Since April 2018 he is the President of the Macro Synthetic Fibre Association (MSFA).
Time and Place
The presentation will take place electronically on Thursday, 18 August 2022 at 18:30 hrs. The presentation will take approximately 45 minutes, follow by 15 minutes of questions/discussion.
This is the 237th in a series of presentations by TUCSS and is open to current TUCSS Members only. Seats are on first-come-first-served basis and limited to 500 persons.
Members are to sign up for the seminar via their TUCSS account on the TUCSS Website or TUCSS Mobile App. The details on how to access the seminar will be sent to the members who has successfully signed up for the seminar, at a date nearer to the seminar. The deadline for registration is on Monday, 8 August 2022 or when total registered participants reaches 500 whichever comes earlier.
For members who require certificate of attendance, please note of the attendance policy:
- Login at the beginning of the seminar (link will be assessable at 18:15 hours)
- Evidence of participation by video switched on throughout the seminar
- Complete the quiz at the end of the seminar before logging out. The duration for the quiz is 15mins.
Certificate of Attendance will be uploaded to the member’s account after the compliance to the Attendance Policy is verified.
Points have been applied and pending approval.
NOTE TO MEMBERS
Note 1: Members are not required to indicate their names and TUCSS registration details through Chat function. Members shall not send messages through Chat function during the presentation.
Note 2: Higher no-show was observed at the last TUCSS monthly seminar. As there are limited openings for the seminar, members are urged to register for the seminar only if they can attend the seminar.
Note 3: For any suggestions/feedback to improve the online seminar, members are to email to the secretariat.