This project involved the design of a foundation modification for an existing tower.

Challenge: Equipment loading changes caused overstresses to this 187-foot guyed tower’s foundation.The area around the base of this tower is extremely constrained due to existing equipment in close proximity which made site access for excavation equipment difficult.

PJF Solution: Due to the space constraints of the site, our engineers had to develop a solution that did not require the use of heavy equipment and which also minimized the footprint of the foundation. As a result of these factors, our engineers designed a foundation modification that expanded the square pad in only two directions in order to ensure that the nearby equipment was not disturbed.

Result: Despite the limitations of the site, our solution optimized the available area for expansion of the foundation mat (concrete slab above/below grade) without needing heavy excavation equipment. In addition, the reinforced foundation base was only at 70% capacity which allowed additional available capacity for future equipment upgrades.

The foundation was failing on this 187-foot guyed tower. Our solution optimized the available area for expansion of the pad and no excavation equipment was needed.

This project involved the analysis and modification of an existing tower.
‍
Challenge: The original analysis of this 260-foot guyed tower determined that the tower and one of the guy anchors were not sufficient to accommodate new loading requirements. Costs for reinforcements needed to be minimized and any modifications needed to be quickly completed.

PJF Solution: In order to try and avoid costly modifications, our engineers diligently analyzed different scenarios and eventually determined that adjustments to the guy cable tensions would eliminate the need to complete any reinforcements on the tower structure. A new guy anchor was needed to replace the failing anchor.

Result: Despite initial analysis results that determined modifications were needed to the tower, ultimately, our engineers found a solution that required adjusting the guy cable tensions and only replacing one guy anchor. This solution drastically reduced modification costs. Since guy cables must be re-tensioned when new anchors are added, all the work could be completed at once without the need of a crew to climb the tower thus providing a quick resolution to the overstresses on the tower.

The guy cable tensions were adjusted eliminating the need for tower modifications. In addition, our solution replaced one of the guy anchors which was failing.

This project involved the analysis and modification of an existing radio tower.

Challenge: This 199-foot guyed tower owned by KZFR 90.1 FM had an existing guy anchor that needed to be replaced. In addition, the tower had extensive leg and guy cable failures. The tower was located on an extremely constrained site so there was not adequate space to expand the guy anchor radius and still remain within the property lines. Also, modification costs needed to be minimized as much as possible.

PJF Solution: The most economical modification for this tower would have been expanding the guy anchor radius, but since this was not an option due to limited space, our engineers had to find a creative solution. The new guy anchor that was needed was strategically placed in close proximity (10° counterclockwise) from the outermost anchor but still matching the existing radius. Our solution called for replacement of three of the original guy cables with larger cables and the addition of a new cable. All the guy cables were attached to the new anchor and then tensioned. In order to relive the stresses on the legs, 60-feet of bracing was added to reinforce the tower legs.

Result: Despite the limited space of the site, our solution enabled a new larger guy anchor to be installed within the property line. The new anchor supported all the guy anchors. Since our solution maintained the maximum radius, less bracing was required to reinforce the tower. The use of bolt-on bracing to reinforce the tower leg did not require aerial welding which helped minimize modification costs.

The tower had extensive leg and guy cable failures. The guy anchor radius could not be expanded due to the size of site.

This project involved the potential reinforcement and eventual replacement of an existing 1,500-foot broadcast tower.
‍
Challenge: The FCC spectrum repack, the program that mandated some broadcast companies to switch frequencies to make more spectrum available for wireless broadband, required antenna changes on this existing 1,500-foot tower. Based on the initial structural analysis, more than half of the tower required reinforcing to accommodate the new equipment including the base and guy anchor foundations, both of which would be costly to complete.

PJF Solution: Our engineers developed modification drawings and subsequent cost estimates. After evaluating the reinforcement costs and taking into account the existing rust damage on the tower and the fact that the reinforcement would only provide capacity for the new equipment and no future use, our team of engineers recommended that tower replacement was a more economical solution.

Result: Our team recommended that this broadcast tower be replaced to meet the current loading needs and provide additional capacity for future use. In addition, our engineers assisted the broadcast company with the required submittal letter needed for the FCC to assist in securing financial backing for replacement of the tower.

More than half the tower would need reinforcement after antenna changes. As a result, our team recommended that this massive guyed broadcast tower be replaced.

This project involved transforming an existing 195-foot self-support tower into a guyed tower.

Challenge: Increased carrier activity and new loading from equipment changes caused overstresses on this existing self-support tower. Over 80% (160 feet of the total 195 feet) of the tower legs were failing. Furthermore, other bracing members, the anchor rods and the foundation were overstressed. Extensive failures of the legs and anchor bolts would require costly field welded solutions.

PJF Solution: Based on the widespread failures of many of the elements of this tower including 160 feet of the tower legs and subsequent anchor bolts and foundation, the potential modifications would have been costly. As a result, our engineers needed to find a creative solution to provide the needed reinforcements more economically. Our solution involved adding three levels of guy cables to the existing tower which significantly reduced the modifications needed. Although a small amount of bracing was still required for connection of the cables, our team specified a bolted solution so no field welding was necessary. The addition of the guyed cables also reduced the stress ratio on the anchor bolts and foundations to a level that no modifications were required for these parts of the tower.

Result: The conversion of this self-support tower to a guyed tower improved the load capacity and eliminated expensive modifications to the anchor bolts and foundation.

Our solution involved adding three levels of guyed cables to the existing tower which eliminated the need for expensive modifications to the anchor bolts and foundation.

This project involved the analysis and modification of an existing guyed tower.
‍
Challenge: This 580-foot tower was analyzed by another engineering firm. The results of that structural analysis were that the tower was failing. The client was told by the other firm that reinforcement modifications would “be impossible” and recommended that the tower be replaced.

PJF Solution: After reviewing the other firm’s results, our engineers were convinced that a modification solution could be developed. Our team completed a detailed structural analysis. Based on our analysis, not only was a modification plan developed, but our proposed reinforcements were an economical remedy for the tower. As a result, the existing guyed cables were replaced, tower bracing was added and the existing foundation was reinforced.

Result: Despite being told by another firm that the tower could not be reinforced and needed to be replaced, our engineers reanalyzed the tower and developed modifications to ensure its continued use.

After another firm said that reinforcement of the tower would be impossible, our team proposed that the guyed cables be replaced and the foundations be reinforced.

This project involved the design of a foundation to support a new monopole which was needed to replace an existing self-support structure.

Challenge: A foundation design was needed for this new monopole, which was designed by another firm. The new pole was designed to be 184 feet tall to accommodate equipment platforms for six wireless carriers housed on the pole. The pole will be located at the top of a ridge where higher wind speeds on the structure exist. The steep slopes of the ridge also made access to the site for equipment and supplies difficult and limited the area available for the needed foundation mat (concrete slab above/below grade). Furthermore, rock begins five feet below grade which was not conducive for the client’s typical drilled pier (deep drilled shaft reinforced by concrete and steel) foundation.

PJF Solution: Since the client’s standard foundation system would not be economical to construct based on the limitations of the existing site and the expensive cost associated with drilling through rocky substrate, our engineers had to develop a new solution. A rock anchor system was developed. The key to our solution was to minimize the number of anchors included in the mat which was limited in sized (20 foot squared) due to the site.

Result: Despite having to minimize the size of the mat, our solution optimized the rock anchors installed while efficiently transferring the load from the pole to the new rock anchors.

Rock anchors were maximized on the 20’ x 20’ mat. Installation of rock anchors transferred the load path from pole anchors to rock anchors.

This project involved the design and repair of a damaged foundation for an existing monopole.
‍
Challenge: The foundation of this monopole structure was damaged during drilling for post installed anchor rods. During drilling, the rebar cage that provides stability for the drilled pier was cut compromising the integrity of the structure. In addition, the area around the base of the monopole is extremely constrained and could not accommodate large excavation equipment. The foundation shaft also contains several underground conduits that could not be relocated.

PJF Solution: Due to the space constraints of the site, our engineers had to develop a solution that did not require the use of heavy equipment and which also minimized the footprint of the foundation. Further complicating the foundation design was the existing underground conduits that could not be disturbed. As a result of these factors, our engineers designed a new foundation system utilizing three smaller diameter piers positioned in a triangle around the original cassion. These smaller piers were installed with equipment that could access the site and the footprint was minimized by having a triangle shape.

Result: Despite the limitations of the site, our solution optimized the available area for the foundation mat (concrete slab above/below grade) without needing heavy excavation equipment. Our unique design also ensured that existing underground conduits were not disturbed or damaged and created additional capacity for the foundation.

Unique triangular mat design optimized the available area on the site. In addition, the installation of three smaller piers needed to be carefully planned to avoid existing conduit.

This project involved the design of a new massive monopole constructed on a steep sloping mountain site.

Challenge: A foundation design was needed for this new monopole which was to be 150 feet tall to accommodate equipment platforms for six wireless carriers housed on the pole The foundation design specified a single pier with an outside diameter of 10feet (most monopoles’ diameters top out at 6 feet).This enormous pier also needed to be 50 feet long to provide support below ground. The pole is located on a mountain where higher wind speeds on the structure exist. The steep slopes of the ridge also made access to the site for equipment and supplies difficult and limited the area available for the needed foundation mat (concrete slab above/below grade).

PJF Solution: Since heavy excavation and drilling equipment could not be used on the site, our engineers had to find a creative solution that did not require this type of equipment but still provided stability and support for the massive structure. Our solution utilized a large mat (concrete slab above/below grade) with four smaller diameter (four foot) piers positioned at each corner of the mat. The smaller piers positioned at the corners did not need to be as long as the originally specified pier due to the position on each corner. This structurally sturdy design provided ample stability and support for the new pole.

Result: Despite the limitations of the site, our solution eliminated the need for heavy equipment. Our unique design was constructed using only concrete and rebar which was an economical solution for the client since specialized materials or installation was not required.

Original foundation design was 50 feet deep but our design did not require that depth. Single massive pier was replaced with four smaller piers positioned at corners.

This project involved the design of a new foundation for a new monopole constructed on a mountain ridge in a national forest.
‍
Challenge: A foundation design was needed for this new 85-foot monopole which is located in the Lincoln National Forest, a region that requires site work to disturb the area as little as possible. The pole is located on a mountain ridge where higher wind speeds on the structure exist. The site is only accessible by an unmaintained dirt road. In addition, the steep slopes of the ridge also made access to the site for equipment and supplies difficult and limited the area available for the needed foundation. The new pole also needed to be installed quickly.

PJF Solution: Since heavy equipment could not be used on the site due to limited access, our engineers had to find an innovative solution that did not require this type of equipment but still provided stability and support for the structure. Our solution also has to take into account the fact that the impact on the area needed to be minimized. As a result, our solution utilized ARE Telecommunications AFS1700 Foundation System, which is a foundation that is pre-fabricated and can be installed at grade so no heavy equipment is needed for transport or installation. The system was also able to be fabricated and installed rapidly.

Result: Despite the limitations of the site, our solution eliminated the need for heavy equipment and also minimized the impact on the environment. Our unique design is also reusable so it can be disassembled and moved to another site, if needed.

This ballasted foundation is installed at grade which minimizes the impact on the site environment.

This project involved the repair to an existing foundation to accommodate additional loads.
‍
Challenge: New loads on this 400-foot self-supporting tower caused the foundation to begin failing. When the wind blew on this tower, the leg of the tower was tying to lift out of the ground due to the new loads. The area around the base of the tower is extremely constrained by other telecommunications equipment including generators and would not permit the use of large equipment for repair. In addition, beneath the tower there are several underground conduits and utilities.

PJF Solution: Due to the space constraints of the site, our engineers had to develop a solution that did not require the use of large equipment and which also minimized the footprint of the foundation. Our solution also has had to take into account the existing underground conduits that could not be relocated. Our engineers designed a foundation that included the addition of two smaller diameter piers positioned on either side of each leg of the tower. The additional piers were just over 2.5 feet in diameter. These new piers could be installed with smaller equipment that was able to access the site and was cheaper to use making the cost of the modification more economical. Our design also encased the existing three foundation piers and the six new piers with a new mat (concrete slab above/below grade).

Result: Despite the limitations of the site, our solution was installed without the need for heavy equipment and provided additional capacity for the foundation to handle the new loading requirements which ensures the foundation capacity matched the tower’s capacity.

The area around the base of the tower is extremely constrained with other equipment. As a result, smaller piers were installed on either side of each tower leg.

This project involved the design of a foundation for a new wireless communications tower.
‍
Challenge: The site for this new wireless communications tower is located near Ellen D Mountain on land owned by the Bureau of Land Management (BLM). BLM’s requirements state that any construction work must minimize the impact on the environment. In addition, foundation work not only has to reduce disruption to the ground, but it also has to allow for future removal without permanent impact to the site. The work also needed to be completed as quickly as possible for less disruption to the area.

PJF Solution: Due to the space constraints of the site and the strict requirements for minimal disruption to the area, our engineers developed a precast modular foundation using the “Cell Blocks” system. This system utilizes precast concrete post-tensioned (method of reinforcing concrete by embedding steel cables that are stretched to create tension) slabs for the foundations. Our solution joined 25 of these slabs together to create the 35’ x 35’ foundation which sits at grade so no excavation was needed.

Result: Since BLM had specific regulations regarding land use and permanence, our non-penetrating foundation ensured these specifications were met. This foundation was also able to be installed in a day and the entire project was completed in less than a week.

The Cell Blocks system uses precast concrete post-tensioned slabs for the foundation. This system was selected since access to the site was difficult due to its location on a rugged mountain ridge.

This project involved new equipment loading on an existing mount located at the top of this tower.
‍
Challenge: Additional loads created by the new equipment overstressed the mount making it unsafe to install the new equipment. The existing mount is located at the top of the tower which limited the area in which modifications could be installed since there was no structure above the mount to which reinforcement could be secured. Based on time constraints and costs, the preferable remedy needed to incorporate an “off-the-shelf” modification kit rather than a custom solution. Standard connection hardware included in the “off-the-shelf” modification kits would not fit the mount face and support rail members which were made of steel angle shapes.

PJF Solution: Based on the limitations of the prefabricated modifications kit and the location of the mount on the tower, our engineers had to develop a creative solution. Our team proposed the installation of longer mount pipes extending below the mount face and then using the support rail provided in the kit in a unique manner by installing it below the mount to serve as support. A kicker kit with angle supports was installed on this new support rail further strengthening it.

Result: Due to the configuration of the reinforcement, the load path was transferred from the overstressed mount members to the new support rail and kickers resulting in higher structural capacity for the mount system, which enable the new equipment to be safely installed.

A kicker kit with angle supports was installed on the new support rail. Existing mount pipes were replaced with longer pipes to extend below the mount face.

This project involved new equipment loading on an existing 12’ mount platform located on the top of this pole.
‍
Challenge: The face horizontal components and support rails were overloaded due to stresses created by new loading requirements. Due to the way that the original mount was configured, reinforcement of the face horizontal rails and the support rails was difficult. In addition, the existing support rail was a steel angle member which is a less structurally efficient shape than a pipe support rail. Based on this configuration, the load path needed to be redirected in order to relieve the stresses on the existing structural members.

PJF Solution: Our engineers determined that the failing members would not be able to easily be reinforced and, therefore, needed to determine a solution that redirected the load path thus relieving the anticipated stresses on the existing members. In order to change the load path, a kicker kit was installed. Our team also determined that the existing support rail required a larger bending capacity which meant replacing the existing angle support with a pipe. This simple change in shape had a dramatic effect on the amount of load that the support rails could sustain.

Result: The changes in the load path through the installation of a kicker kit and changing to a pipe support rail significantly improved the load capacity of the mount and support rails.

The face horizontals and support rails were overloaded due to stresses. A kicker kit was installed and existing angle supports were replaced with a pipe.

This project involved new equipment loading on an existing 6.5’ circular mount platform located on this pole.
‍
Challenge: Due to the way that the original mount was configured, the new loading was creating additional stresses on the mount pipes, face horizontal rails and the connection point (standoff) to the pole. In addition, the size of the existing mount pipes was not adequate to handle the additional load. Based on this configuration, the load path needed to be redirected in order to relieve the stresses on the existing structural members.

PJF Solution: The face horizontal components, mount pipes and standoff were failing due to stresses created by new load requirements. These failures were determined utilizing RISA 3D analysis. In order to change the load path, a kicker kit was installed which connected the standoff and the support rail and transferred some of the load from the standoff to the kicker kit components. Our team also determined that the existing mount pipes were not sized correctly to support the new loads and recommended that larger size pipes be installed.

Result: The changes in the load path through the installation of a kicker kit and increasing the size of the mount pipes increased the load capacity of the tower connection, mount pipes and face horizontal supports.

New loading was creating additional stresses on the mount pipes, rails and standoff. Failures were determined using RISA 3D.