April 2022 Vol. 77 No. 4
Rehab First Look
New Software Simplifies, Facilitates Use of ASCE MOP 145 for Close-Fit Liners
Jeff Griffin | Senior Editor
Last fall, the American Society of Civil Engineers (ASCE) published Manual of Practice (MOP) 145, Design of Close-Fit Liners for the Rehabilitation of Gravity Pipes. The committee was chaired by Norman “Ed” Kampbell.
MOP 145 offers valuable guidance to consulting engineers for designing flexible, close-fit liners for rehabilitation of existing gravity pipe, including sanitary sewers, culverts and storm sewers. The design applies to CIPP, both non-reinforced and GRP-reinforced, and fold-and-form liners.
To simplify correctly implementing MOP 145, new software has been developed by Jadranka Simicevic, MSCE, M. ASCE, owner of JPS Consulting, LLC. Simicevic was one of the contributors to MOP 145.
The software is called CLinT Calculator and has been available since January 2022 – in imperial and metric versions.
Simicevic has extensive experience in developing engineering software and writing codes for solving computational problems. With an in-depth understanding of the new design method, she said it was a natural step to undertake the development of the MOP 145 software.
“The MOP’s design method is very complicated, consisting of multiple design procedures, which in a given pipe design, apply based on the existing conditions and various design requirements,” she said.
“While working on the manual and developing the understanding for different design procedures, which were ultimately depicted in the numerous flowcharts and described in detailed steps in the manual, I created various Excel worksheets to get the feel for the calculations.
“It was challenging because of many complicated formulas using a large volume of input and calculating parameters. There were also other issues, including numerical instability in some calculations. I was very fortunate that I had support and guidance from Dr. Olivier Thépot, who developed the French design method the manual is based on. It was clear that once the manual is published for the widespread use of this design method in practice, this would require a robust and easy-to-use software.”
What CLinT can do
CLinT can design liners for circular and noncircular pipes, either all curved around the perimeter or with flat sections. Built-in profile shapes cover a majority of sewer and culvert pipes that may need lining today, said Simicevic.
She continued. “CLinT has the capability to identify the locations in the liner profile where the load effects from the external loading are the greatest (design arcs) for the selected host pipe shape,” she continued. “The behavior and response of the liner to the loading is different in rigid and flexible pipes, which is built into CLinT. This includes typical cracking modes for different shapes of cracked rigid pipe built-in.”
CLinT requires few geometry input parameters (only the minimal number necessary to specify the present-day host pipe geometry). It will solve the remaining profile geometry (arcs’ radii, opening angles, perimeter) for various host pipe shapes.
Gap forming between the liner and the host pipe during and after liner installation is an important parameter. CLinT calculates this, as described in MOP 145 (max value 0.04 inch). However, CLinT also can perform design calculations with fixed value of gap exceeding the limit. This enables checking the liner thickness during design reconciliation after the liner has already been installed.
CLinT has a list of AASHTO and AREMA surface live loads built-in and will calculate loads on the pipe/liner for the selected load. For deep pipes, CLinT provides an option to apply tunnel loading, per ASCE 27-17, when calculating the soil overburden pressure.
Different types of generic lining products with assumed material properties are also built into CLinT. Actual lining products and their properties to be used in given pipe rehabilitation can be added to CLinT and should be used in the calculations.
The MOP 145 method includes two design procedures for checking the stability and material strength under groundwater pressure (critical and subcritical). It has additional procedures for checking the material strength under deferred ovalization in flexible and cracked rigid pipes, and for checking the stability and material strength under all loads, in case of more severely deteriorated pipes.
CLinT will test different conditions and requirements in ongoing iterations to identify and apply the proper design procedures, switching automatically from one procedure to another, as needed, and will carry on the iterations until all design requirements are met.
Two output reports can be generated after completed calculations: a one-page summary and more detailed calculations. Both reports come with a cover page, where project information. can be added.
User friendly
Simicevic explains that data input is nicely organized on the screen and simple to complete, with drop-down lists and a small number of input fields.
“The use of the software,” she added, “including data entry, performing the calculations and result outputting, is quite intuitive and further simplified with tips on the screen and information buttons.
“Drawings on the screen and in the reports clarify the required input and the performed calculations. The calculation is all automatic and once you enter all input parameters, you only need to click on the CALCULATE button. CLinT will complete the calculations.”
CLinT is written as a Microsoft Access standalone application. To run it, MS Access must be installed, which is included in Office 365. Another requirement is a 64-bit computer.
CLinT is available as a subscription-based software. An annual license can be purchased for a single user on one computer. Details on ordering can be found on the software webpage, https://clintcalculator.com.
“A demo can be requested before ordering CLinT,” Simicevic said. “It takes approximately one hour to show how the software can be used.”
User testimonial
Simicevic introduced Chris Macey, with engineering firm AECOM, an expert in pipeline rehabilitation who has contributed to numerous endeavors in NASSCO, AWWA, NASSCO, NASTT, ISO Committees, etc., over past several decades. As one of the peer-reviewers of MOP 145, and the first user of CLinT, as soon as it was released in early January, he provided a testimonial.
“CLinT software is the tool to immediately put the new design method in use and I am very excited about it,” said Macey. “The industry reaction to the new design method is largely favorable, as many are cognizant of the need for better design approaches for close-fit liners.
“We have long understood that the way we used to design close-fit liners is considerably different than the way they truly interact with the host pipe and the soils around it. Design that varies that far from reality is never a good idea. This is particularly true for non-circular pipes, as well as circular pipes with more complex loading situations.”
He also commented on how the new MOP 145 design approach is very different from past design approaches.
“I have been following work of Olivier Thepot on non-circular close-fit liner design for many years,” he continued, “and I am familiar with it, but this is a big leap for many, a quantum design leap. The way forward for the new MOP 145 approach should be implemented in a carefully staged manner, like any new engineering endeavor.
“Practical engineering judgment learned from past designs, balanced with the use of what is known to be a more accurate view of assessing the long-term structural resistance that is needed for close-fit liner installations, are keys to success. This, in conjunction with verifying that what we have done in construction truly matches what we intended to do in design, are critical aspects of moving forward successfully.”
Macey has been using CLinT on a number of active projects.
“These projects are good examples of ASCE MOP 145 being implemented intelligently in real-life, practical applications,” he said, “and will be useful for all practitioners. CLinT has been performing very well and AECOM is getting additional licenses for other employees.
“I see CLinT being very useful in all project phases, from tendering to the bidding and construction phase, so I will recommend this software for use to many others in the industry. I am optimistic that CLinT will help the public at-large benefit from the new design approach as expeditiously as possible.”
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