Tower Engineering and Structural Engineering Services
Field Measurement of Existing Structures
When drawings of the existing tower are not available, Landa and Associates INC., client or subcontractor, will visit the site and will collect the information listed below (necessary) to perform a tower structural analysis.
a) Identification of the original tower manufacturer (and design number), if possible.
b) An inventory of the existing antenna, antenna elevation, and antenna feed-line size and quantity on the tower.
c) Field measure the tower to determine the tower bracing configuration, section heights, dimensions and member sizes as well as the portion of the foundation above grade. (we will not be able to determine the size of the foundations below grade)
d) Pictures will be provided that indicate the general construction and layout of the tower.
e) Any obvious defects, that happen to be noticed in the course of the tower measurement will be brought to your attention. (we will not be performing maintenance and any defects discovered will not be corrected while we are on site)
f) We will not be identifying utilities, site access, buildings, roads, property boundaries etc.
g) This service must be distinguished from an inspection. The purpose of the site visit is to MEASURE the tower and not to inspect the physical condition of the tower. Neither Landa and Associates, INC nor our subcontractor shall be held responsible for any physical tower defects that go unnoticed.
Structural Analysis of the Existing Tower
Landa and Associates, INC will have the existing tower analyzed in accordance with either the Electronics Industry Association Standard EIA/TIA-222-F 1996 or TIA-222-G 2006 (excluding seismic calculations) to determine if the tower can safely support the additional loads (as defined by the client) without requiring any modifications to the existing structure, and provide the following:
a) The tower will be analyzed in accordance with the TIA standard considering both the no ice condition and with radial ice accumulation (unless the tower is in an area of the country not subject to ice accumulation). The safe capacity of the tower will be stated in percent utilization of the safe member capacity. At least three sets of computer calculations will be submitted. A seismic (earthquake) analysis is not included as part of a standard structural analysis
b) We will verify the safe capacity of all the main load-carrying structural members but will not be able to analyze every structural sub-component on the tower such as plate thicknesses, weld sizes, etc. since this detailed information is rarely available.
c) Our structural analysis will be based upon the assumption that all structural members have the same load carrying capacity as the day the tower was built. We will not be evaluating the effect of corrosion and we will assume that any damaged or otherwise defective, members will be replaced.
d) A structural analysis report will be provided, discussing the results of the structural analysis and any assumptions that had to be made. The report will identify any overstressed members, state the percentage of overstress, and discuss, in general terms, what can be done to increase the load carrying capacity of the tower to meet the minimum wind and ice recommendations of the TIA standard.
e) The tower elevation drawing produced by the RISA-Tower computer program will also be provided. This is a "stick drawing" in that it does not show member widths or connection details. If the tower meets the TIA recommendations without requiring any modifications a professional engineers seal for the state in which the tower is located will be placed on the drawings.
Tower Reinforcing/Modification drawings
Landa and Associates, INC will provide drawings that indicate the modifications required to increase the structural capacity of the tower to meet the minimum recommendations of the TIA standard. We will not be producing shop (fabrication) drawings. We will provide drawings that can be issued to solicit competitive bids for the tower rework. The information we will provide is described as follows:
a) Landa and Associates, INC will assume that standard items such as guy hardware, guy rods, star-mounts, antenna mounts etc. will be purchased from a knowledgeable reputable tower manufacturer and will not need to be designed or detailed.
b) All existing tower members that are to be reinforced, replaced, or braced will be identified as to the existing member size and location on the tower.
c) The size of all new steel members that are required and the method of attachment to the existing tower will be indicated on the drawings. All bolt sizes and weld sizes will be clearly indicated. Landa and Associates, INC will be available to answer questions from the bidders or the construction contractor.
d) The drawings will be in sufficient detail to allow shop drawings to be produced by a construction contractor with a minimum of field measurement. The construction contractor will be responsible for the proper fit and clearance in the field.
e) We will not be providing construction cost estimates for the rework. This is because we are not general contractors and this type of work is very labor intensive and can't be accurately estimated solely based upon the weight of the reinforcing material.
f) The tower reinforcing drawings will be stamped by an engineer registered in the appropriate state. We will provide prints in sufficient quantity to obtain a building permit and for your company to retain as a record set of drawings.
Structural analysis of towers and poles modifications.
We would like to quote tower modification designs and drawings as a separate fee. This is because we do not know if the tower will require modifications before the initial analysis and if it does require modifications, we have no way of knowing how extensive they may be. After we complete the initial analysis, we can accurately determine our scope of service and will quote a lump sum (not to exceed) additional fee. Of course, if the tower does not need to be reinforced, there will be no additional charge.
We try to provide a turnaround of no more than one week (five working days) for a single tower analysis from the time that we receive all the tower and antenna information. This can vary depending upon our workload at the time. Of course, if there are multiple sites given to us at one time it will take longer to get the whole group of analysis completed.
© Copyright 2004, LANDA AND ASSOCIATES, INC, NEVADA CORP.
