Structures

Axial Capacity of Reinforced Gasketed Joints

Anonymous — Wed, 30 Sep 2020 06:00:00 +0000

Axial Capacity of Reinforced Gasketed Joints Anonymous (not verified) Wed, 09/30/2020 - 00:00

Full Project Title: Axial Capacity of C900 PVC Pipe with Reinforced Gasketed Joints

Year: 2019-20

Industry Partner: Denver Water

CIEST Personnel: Jessica Ramos, John Hindman, Brice Lucero, David Ballcells, Hayley Parnell, and Porter Hawkins

Primary Investigator: Prof. Brad Wham

Summary: The objective of this study was to impose externally applied axial loading to reinforced gasketed water pipeline joints to establish upper bound performance under worst case conditions of ground movement. Test protocols included axial tension and cyclic (progressive tension and compression) loading on bell-spigot style C900 PVC pipe to simulate deformations possible during natural hazards such as earthquakes and landslides . The test specimens consisted of either RieberLok Gasketed or Diamond Lok-21 pipe with a restraining ring. Tests provided measures of axial displacement capacity, pipeline connection strength, and failure mechanism. The results indicated these systems as potentially viable solutions for regions prone to persistent soil movement and settlement. Tests were conducted in partnership with Denver Water.

Failed specimen after testing in tension.

View the full report here.

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Biomimetic Antifreeze Polymers

Anonymous — Fri, 14 Aug 2020 16:56:27 +0000

Biomimetic Antifreeze Polymers Anonymous (not verified) Fri, 08/14/2020 - 10:56

Full Title:

Year: 2017-21

Participants: Mohammad Matar, Shane Frazier, Jorge Osio-Norgaard, Anastasia Aday, Nathan Deanda, El Delesky

Primary Investigator: Wil Srubar III

Summary: In this study the effects of biomimetic antifreeze polymers were investigated for their use as an alternative to traditional air entraining agents in concrete exposed to freeze-thaw conditions in accordance with ASTM C666. Compression testing according to ASTM C39 was conducted to examine the changes in strength of polymer-modified concrete as compared to concrete containing a commercial air entraining agent. Various molecular weights and concentrations were explored in concrete samples containing polymer modifications. Results indicate that biomimetic antifreeze polymers do not significantly affect the compressive strength of concrete and may provide an alternative to traditional air entraining agents at lower concentrations than their air entraining admixture counterparts.

Image at Right:

Specimens with entrained air after freezing and thawing
Test specimen undergoing compression test
Specimens with biomimetic antifreeze polymer after freezing and thawing

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Geopolymer Cements

Anonymous — Thu, 13 Aug 2020 21:05:48 +0000

Geopolymer Cements Anonymous (not verified) Thu, 08/13/2020 - 15:05

Full Title: Geopolymer Cements: Resistance-Engineered Sewer Infrastructure for Longevity using Innovative, Energy-efficient, Synthesis Techniques (RESILIENT)

Year: 2016-21

Participants: Mohammad Matar, Xu Chen, JP Gevaudan

Primary Investigator: Wil Srubar III (CU Boulder)

Co-Investigator: Claire White (Princeton University)

Summary: The primary objective of this Extremely Durable Cementitious Materials project is to engineer an ultra-acid-resistant low-calcium alkali-activated (geopolymer) cement paste specifically for wastewater (i.e., sewer) infrastructure applications to address the critical need for concrete materials with enhanced biogenic sulfuric acid resistance compared to ordinary portland cement (OPC) concrete.

In the United States, local governments spend approximately $50 billion annually on the construction, operation, and maintenance of over 800,000 miles (1,300,000 km) of concrete sewers – $13.8 billion of which is specifically used to prevent and mitigate the effects of microbial-induced concrete corrosion (MICC). While sulfuric acid destabilizes and dissolves the calcium-rich phases in OPC, yielding weak, gypsiferous reaction products and deterioration severe enough to cause collapse, low-calcium geopolymers laden with polyvalent cations (i.e., Mg(OH)2, Fe(OH)3, and, in some cases, Ca(OH)2) have been shown by the PI, Co-PI, and others to exhibit exceptional acid resistance to sulfuric acid compared to OPC.

The resulting geopolymer cement paste formulations will exhibit 80% reductions in steady-state biodeterioration rates compared to OPC concrete (from ~5 mm/year (0.20 in.year) to ~1 mm/year (0.04 in/year)), which will extend the service life of concrete sewer infrastructure ~5X and will yield reductions in total life cycle environmental (i.e., embodied energy and embodied carbon) costs of mitigating biogenic sulfuric acid degradation by ~75%.

Image above:

Microbial-induced concrete corrosion. Sulfur oxidizing bacteria (SOB) generate sulfuric acid on the crowns and in the headspaces of concrete pipes, converting Ca-rich binder phases to weak, gypsiferous reaction products.

Metal cation additions effect on improving the sulfuric acid resistance of geopolymer cements: Prof. Srubar’s team has shown that (a) Mg2+, (b) Fe3+ and (c) Cu2+ additions show improved acid resistance in highly acidic (pH ~ 2) H2SO4 (i.e., dimensional stability in (a) and (b) and no evidence of dealumination in (c)); Prof. White (Princeton) has utilized DFT to show (d) atomic rearrangements and changes in total energy that occur as Ca2+ is replaced by Na+ in the interlayer of C-S-H gel; a similar technique will be used to identify best-performing polyvalent cations for binder stabilization.

The primary objective of this Extremely Durable Cementitious Materials project is to engineer an ultra-acid-resistant low-calcium alkali-activated (geopolymer) cement paste specifically for wastewater infrastructure applications.

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Engineered Living Materials (BioBricks)

Anonymous — Thu, 13 Aug 2020 19:04:50 +0000

Engineered Living Materials (BioBricks) Anonymous (not verified) Thu, 08/13/2020 - 13:04

Year: 2017-21

Participants: Rollin Jones, Marimikel Charrier, Bruce Zou, Juliana Artier, Aparna Nagarajan, Chelsea Heveran, Jishen Qiu, Liya Liang, Sarah Williams

Primary Investigator: Wil Srubar III, Mija Hubler, Sherri Cook, Jeff Cameron

Summary: The objective of this project is to engineer living materials to serve both biological and structural functions. Living Building Materials (LBMs) were created by inoculating an inert structural sand-hydrogel scaffold with Synechococcus sp. PCC 7002, a photosynthetic cyanobacterium. The scaffold provided structural support for Synechococcus, which toughened the hydrogel matrix via calcium carbonate biomineralization. LBMs represent a platform technology that leverages biology to potentially impart novel sensing, responsive, and regenerative multifunctionality to structural materials for the built environment.

Wil Srubar discusses BioBricks:

The objective of this project is to engineer living materials to serve both biological and structural functions.

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Tension Testing of Flexible Expansion Joints

Anonymous — Sun, 19 Jul 2020 18:26:52 +0000

Tension Testing of Flexible Expansion Joints Anonymous (not verified) Sun, 07/19/2020 - 12:26

Project Title: Tension Testing of Flexible Expansion Joints

Industry Partners: EBAA Iron, Inc.

CIEST Personnel: Hailey Parnell, Lindsay Guerrero, Bruce Lucero

Primary Investigator: Prof. Brad Wham

Year: 2020

Project Summary: The intent of the test program is to investigate the axial performance of a Flex-Tend Flexible Expansion Joint (FEJ) and a Force-Balanced FlexTend Flexible Expansion Joint (FBFEJ), each nominally 6-in. diameter. Externally applied axial tension load test results are compared to data obtained from internal pressure burst tests and demonstrate that, while similar levels of axial force are required to initiate component failure, the failure mechanisms differ and and influenced by the circumfrencial stress supplied during burst testing. The work was undertaken in the Center for Infrastructure, Energy, and Space Testing (CIEST) which is affiliated with the Civil, Environmental, and Architectural Engineering Department at the University of Colorado Boulder.

Follow this link for the Report by H.L. Parnell, L. Guerrero, B.A. Lucero, and B.P. Wham.

Report by H.L. Parnell, L. Guerrero, B.A. Lucero, and B.P. Wham.

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Evaluation of Hazard-Resistant Pipelines

Anonymous — Fri, 27 Sep 2019 06:00:00 +0000

Evaluation of Hazard-Resistant Pipelines Anonymous (not verified) Fri, 09/27/2019 - 00:00

Full Project Title: Seismic Evaluation of Hazard-Resistant Pipelines: Axial Testing of PVC, PVCO, and iPVC Pipe with Coupling

Year: 2019

Industry Partners: East Bay Municipal Utility Department (EBMUD)

CIEST Personnel: Cory Ihnotic, David Kyle Anderson, Jessica Ramos, David Balcells, Brice Lucero, John Hindman, and co.

Primary Investigator: Prof. Brad Wham

Summary: The first in a series of testing programs at CU Boulder CIEST investigating performance of critical lifeline systems under extreme loading conditions. This study focuses on the response of various thermoplastic pipe materials and a coupling connection under externally applied axial and lateral loading. Internally pressurized, 6 in. (150 mm) diameter specimens were tested to failure under various loading scenarios including axial tension, compression, and cyclic loading as well as transverse 4-pt bending. This project initiated the development of self-reacting test frame capable of applying dynamic tension and/or compressive loading in excess of 100,000 lbs (445 kN) to linear structures up to 12 ft (3.66 m) long. CIEST’s 1,000,000 lb (4450 kN) four-post load frame was employed to apply lateral loading.

View the full report here.

Appreciation is extended to collaborators David Katzev and Timothy Harris of EBMUD for their intellectual and practical contributions to the project.

The first in a series of testing programs at CU Boulder CIEST investigating performance of critical lifeline systems under extreme loading conditions.

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Seismic Evaluation of HSS Column Splices

Anonymous — Sat, 29 Jun 2019 04:24:54 +0000

Seismic Evaluation of HSS Column Splices Anonymous (not verified) Fri, 06/28/2019 - 22:24

Year: 2018-2019

Industry Partners: Prescient Co. Inc., J. R. Harris & Co.,

CIEST Personnel: Adan Salvador Camacho, Aldrich Valerian, Brice Lucero, Kent Polkinghorne, and company

Primary Investigator: Prof. Brad Wham

Summary: Project included development of a bi-directional loading system to apply simultaneous axial and lateral loading to 6 in. (15.2 cm) diameter columns and splice connections. Nearly 60 full-scale tests were conducted to support evaluation of a new structural building system for seismic applications. Accredited testing performed to ISO/IEC 17025 standard following protocols provided by FEMA 461.

Project included development of a bi-directional loading system to apply simultaneous axial and lateral loading to 6 in. diameter columns and splice connections. Nearly 60 full-scale tests were conducted to support evaluation of a new structural building system for seismic applications. Accredited testing performed to ISO/IEC 17025 standard following protocols provided by FEMA 461.

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Wire Mesh Tension Testing

Anonymous — Thu, 13 Jun 2019 20:04:59 +0000

Wire Mesh Tension Testing Anonymous (not verified) Thu, 06/13/2019 - 14:04

Year: 2019

Participants: David Kyle Anderson

Primary Investigator: Brad Wham

Summary: In summer 2019, former masters student David Kyle Anderson conducted 28 tension tests on 5 different types of wire mesh used for soil stabilization at CIEST. Wire mesh specific to the application of soil stabilization has been developed over time with variances in mesh geometry, individual wire strength, and number of twists found in the node of wire connections, buta guiding standard of testing material characteristics specific to this classification of mesh has not been developed. Given this lack of a uniform mode of comparison, this project’s goal was to compare the material characteristics of common wire mesh used in the application of soil stabilization under identical loading conditions, providing engineers a basis for selection of an appropriate mesh for a given project.

Read the full report here.

In summer 2019, former masters student David Kyle Anderson conducted 28 tension tests on 5 different types of wire mesh used for soil stabilization at CIEST.

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Structural Testing of Steel Deck Diaphragm Assemblies

Anonymous — Mon, 14 May 2018 17:46:07 +0000

Structural Testing of Steel Deck Diaphragm Assemblies Anonymous (not verified) Mon, 05/14/2018 - 11:46

Year: 2018

Industry Participants: Prescient Co. Inc., J. R. Harris & Co., Ramtech Labortories, Hilti Corp.

Primary Investigator: Dr. Brad Wham

Summary: Structural assessment of cold-formed steel diaphragm assemblies was conducted in accordance with AISI S907. The cantilever-style tests were performed on 12 x 12 ft (3.7 x 3.7 m) square specimens and included both static and cyclic test protocols. Displacements exceeding ± 5 in. (12.7 cm) were applied to capture peak and residual strength of the joist/deck/fastener assembly, providing data relevant to system evaluation for seismically active regions.

Structural assessment of cold-formed steel diaphragm assemblies was conducted in accordance with AISI S907. The cantilever-style tests were performed on 12 x 12 ft square specimens and included both static and cyclic test protocols.

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Alkali Silica Reaction Expansion in Concrete

Anonymous — Sat, 30 Dec 2017 19:30:57 +0000

Alkali Silica Reaction Expansion in Concrete Anonymous (not verified) Sat, 12/30/2017 - 12:30

Year: 2017

Participants: Dr. Victor Saouma, Dr. Mohammad Amin Hariri-Ardebili, David Graff, Robert Sparks, Damon Howard

Summary: The focus of this project is to model the shear strength of concrete panels that have experienced alkali silica reaction. The end goal is to be able to derive an equation that relates the shear strength of the concrete to ASR affliction.

The focus of this project is to model the shear strength of concrete panels that have experienced alkali silica reaction.

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