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Engineers’ Syndicate Recommends Amending Building Code after Earthquake

22-11-2023/in HLP, News /by Rand Shamaa

The Syrian Arab Code Committee in the Syrian Engineers’ Syndicate recently issued its recommendations regarding developing a code for constructing earthquake-resistant concrete buildings. This was based on a study of the causes and consequences of the earthquake on February 6, 2023.

The Syrian Arab Code for the design and implementation of reinforced concrete structures is an urban construction system for designing and implementing buildings to achieve acceptable safety in construction. Engineers and building contractors must apply this code in their design studies when seeking construction permits. The Engineers’ Syndicate and administrative units oversee compliance with the code during various construction phases.

Syria’s prime minister formed joint committees in the four governorates most affected by the February 6 earthquake, Aleppo, Lattakia, Idlib and Hama, to assess the conditions of collapsed and damaged buildings. These committees, known as the Quintuple Committees, consisted of five members each: the head of the General Company for Engineering Studies (GCES) branch, the head of the Studies Department in the Technical Services Directorate, a representative from the Engineers’ Syndicate, a university representative, and a representative from the Contractors’ Syndicate. These committees visited the sites of damaged buildings, reviewed their structural studies, and conducted tests on the resistance of concrete and reinforcement steel and soil properties at the sites. They prepared extensive reports outlining the causes of collapses and cracks.

The reports indicated that the damaged buildings were not designed or executed according to the building code, with most collapses and cracks due to poor implementation and lack of soil tests. However, this conclusion is inaccurate, as many of the buildings designed and executed according to the Syrian code for construction collapsed, especially in the city of Lattakia.

Based on these reports, the Syrian Arab Code Committee met and issued its latest report, which the Council of the Engineers Syndicate ratified. Although the Code Committee affirmed that the current code requirements were sufficient to resist earthquakes, it decided to continue developing the code and its appendices. This decision came in response to what the committee described as directives from the Council of Ministers on the necessity of code development in coordination with the National Center for Earthquakes to update Syria’s seismic maps, making the code compliant with the latest global expertise.

However, the recommendations of the Code Committee implicitly acknowledge shortcomings in the code regarding soil mechanics, reinforced concrete, foundations, shear walls, and reinforced steel. Among these, the recommendations emphasize the necessity of conducting at least two soil tests at the construction site after excavation: the first at a depth of no less than five meters below the basement level to determine the soil type and the second at a depth ranging from 15 to 30 meters below the foundation level to determine the required foundation depth unless a rock layer is reached at a depth of five meters across the entire site.

The recommendations also include increasing the cross-section of reinforcement steel bars and the required quantity of reinforcement steel in concrete buildings. Every building taller than five storeys should consist of a shear wall in each direction, with symmetry maintained wherever possible. A shear wall is a load-bearing wall made of reinforced concrete built to the full height of the building.

The recommendations stipulate that no additional storeys be allowed on any existing building unless the building was originally designed to accommodate the extra height as per its granted permit. Even in this case, the administrative unit and the Engineers’ Syndicate must issue a structural, technical report proving that the building’s condition can withstand the additional storeys. It is important to note that property owners can modify the construction permit and increase the number of storeys if an engineering structural report confirms that the building’s foundations could bear the required additional weight, with the approval of the relevant municipal departments.

The recommendations emphasise the need to intensify tests conducted on high-strength reinforcement steel used in construction and prohibit cladding any building before issuing a technical report confirming its structural safety. This is partly a consequence of the impact of the lengthy duration of many construction projects and the long time gaps between construction and cladding phases. which weaken the buildings’ earthquake resistance. Construction can span decades, particularly for public sector projects, which lead the concrete structure of the built unit to remain exposed and unprotected from the weather for long periods.

The Code Committee also referred to a set of issues that were discussed in its meetings but have not yet been decided upon. Among these issues are studying seismic maps through a joint committee from the Syndicate, the Atomic Energy Commission of Syria, the Higher Institute for Earthquakes, and the National Center for Earthquakes, to review and develop the current seismic maps in coordination with the Syrian Arab Code Committee.

Additionally, there is a focus on securing and using seismic measurement devices and expanding their usage to include the study of most construction sites. This also involves expediting the soil classification for various sites and securing equipment that assists in this process, to use the results in designing earthquake-resistant buildings. The report proposed to form a committee in each branch to review soil reports.

It also emphasises the importance of meticulous study and quality control through highly qualified engineering supervision, achieving the technical specifications of the used materials, increasing the stages of review during the project, and prohibiting the construction of additional storeys before ensuring the quality of the structural elements in the lower storeys, both in terms of steel and concrete.

There is a stress on the necessity of certifying any new building by a qualified technical committee, and this committee should verify the correctness of the implementation and conduct some possible tests. Solutions need to be found for addressing violations, narrow streets, and construction on geological faults and agricultural lands, as they are extremely dangerous and prone to collapse in the event of an earthquake.

Notably, the committee asked the Syndicate’s Council to issue a circular to prevent the use of recycled and locally manufactured reinforcement bars that do not meet the code requirements. These bars are made from iron pulled from debris, re-melted, reshaped and sold in the local market.

These observations implicitly indicate the existence of shortcomings in the code’s implementation procedures. The seismic maps are not accurate, as pointed out by many engineers who spoke with The Syria Report after the earthquake, and there is a lack of precise seismic measurement devices. The committee acknowledges the existence of shortcomings in the review of structural studies and the follow-up of the reviewers’ recommendations, in addition to the inaccurate execution of structural studies and deficiencies in the inspection, evaluation and testing procedures before and during the project implementation.

Explained: Issues with the Syrian Construction Code’s Earthquakes Appendix

28-02-2023/in Analysis & Features, HLP /by Rand Shamaa

The Syrian Arab Code for the Design and Implementation of Reinforced Concrete Structures and its earthquakes appendix sets strict standards for construction. However, after the recent earthquake, the damage to buildings licensed under the code raises questions about its effectiveness.

The code and its appendix require specific steps to be followed when constructing an earthquake-resistant building, including criteria on the type of iron reinforcements, the portion of concrete in square metres, and the ratios for concrete mixes, as well as information regarding the design of the structural sequence, i.e. the distribution of the building foundations, retaining walls, and load-bearing shear walls. After completing the design, which indicates that a planned building complies with the standards of the earthquake appendix, it must be submitted to the local administrative unit before obtaining a construction permit.

The Engineers Syndicate and the local administrative unit are subsequently responsible for supervising adherence to the code during the various stages of construction.

When digging begins at the construction site, the builders – usually the contractors – submit soil samples for testing at specialised civil engineering labs affiliated with public universities or government institutions. The records of these test results are documented in an official register that can later be referenced. The foundation design and concrete mixes for the planned building may be modified according to the test results. As the construction process continues, the builder must also present samples of the concrete mix to officially accredited labs to test whether they adhere to the descriptions within the design study. These labs then issue official reports either approving or rejecting the concrete mixes. Like the soil samples, the results are recorded in an official register that can be referenced later.

In short, even considering the cases of negligence and corruption, strict criteria still exist for implementing the code during the design and construction process. Such rigorous standards mean we must examine the code to understand why many licensed buildings collapsed in the earthquake.

First, there is a purely technical issue in the code: the earthquakes appendix uses a cacophony of different scales to measure earthquake intensity, energy, and size, such as the Mercalli intensity scale, the peak ground acceleration (PGA) measured in metre per second squared, the PGA in square centimetres per second squared, and the PGA attributed to the gravitational acceleration scale. PGA measures the ground acceleration during earthquake shaking in a given location.

These scales measure different seismic events using various methods with no direct relationship between them. As such, the earthquake appendix appears to be a mix of scales borrowed from various international construction codes with no clear justification or reason for using them. Remarkably, the appendix leaves out the widely used Richter scale entirely.

Beyond the cacophony of scales, there is an even bigger problem. Part H of the earthquake appendix states that Syria’s most seismically dangerous areas are located in the country’s west, where the PGA measures 300-400 centimetres per second squared during an earthquake. Yet, the appendix requires residential construction designs in these areas to resist a maximum PGA of only 300 centimetres per second squared. It is unclear why the code does not require resistance to a PGA of 400, as expected in these regions.

Because it is difficult to use these complex scales in the design process for earthquake-resistant buildings, engineers hoping to obtain construction permits in western parts of the country design their buildings to resist magnitude-6 quakes on the Richter scale. Theoretically, this is roughly equivalent (albeit with much simplification) to a PGA of 300 centimetres per second squared. In either case, permits are granted for residential buildings in high-density parts of western Syria so long as they can resist magnitude-6 earthquakes, even though the area is at risk of 6.5-magnitude earthquakes and higher.

The code also requires that soil at the excavation level of a building’s foundations be tested but does not require any geological study of the construction site. Such a study would mean examining the geological characteristics beneath the foundation level, which is essential because there may be hollow spaces, aquifers, and sandy, unstable soil in areas close to seismic faults below the construction site. Earthquakes can loosen these underground layers, causing the buildings above them to collapse regardless of how earthquake-resistant they are according to the Syrian Arab Code standards.

The code also fails to account for construction time. Construction in Syria usually takes a long time due to funding issues, complicated bureaucracy, and the need for security approvals. Construction can span decades for public sector projects, social housing and cooperative housing. In such cases, the concrete structure of the built unit remains exposed and unprotected from the weather for long periods. High humidity in coastal areas may erode cement surfaces and cause iron to rust. When construction does resume, no new inspection is done on the concrete structure, leaving the completed buildings vulnerable to collapse in an earthquake.

Explained: Earthquake-resistant Building Design Basics

21-02-2023/in Analysis & Features, HLP /by Rand Shamaa

In the Syrian Arab Code for the Design and Implementation of Reinforced Concrete Structures, there is an appendix on the basic principles for earthquake-resistant building design. It specifies the construction methods to prevent total or partial collapse during earthquakes. In theory, if the code is followed during the design and implementation process, a building will remain intact even if an earthquake’s magnitude on the Richter scale reaches the upper expected limit for that area.

The code lays out four steps that must be followed to construct earthquake-resistant buildings:

A building site’s seismicity (or maximum expected earthquake magnitude) must first be determined. The most significant factors in a site’s seismicity are its proximity to active seismic sources, the seismic history and the frequency of earthquakes in the past 50 years. To help determine seismicity, the earthquake appendix includes a seismic map of Syria created in cooperation with the General Establishment for Geology and Mineral Resources and the Atomic Energy Commission of Syria.The map divides Syria into seismic regions according to the magnitude of expected earthquakes, which are weakest in the east and more severe as the map moves further west. Zone 0 is not considered at risk of significant earthquakes and has a maximum expected magnitude of less than 4.8 on the Richter scale. Zone 1, with a maximum expected magnitude of 5.4, is not at risk of deadly quakes. Zone 2 is at risk of moderate earthquakes of up to 6.1 on the Richter scale. Zone 3 can expect high-intensity earthquakes up to 6.5 on the Richter scale. Finally, Zone 4 is at the highest risk. It can expects devastating earthquakes of over 6.5 degrees of magnitude.
The seismic map of Syria. Source: The earthquakes appendix to the Syrian Arab Code for the Design and Implementation of Reinforced Concrete Structures.
The geological features and soil type of the building site must undergo study. The study includes the soil mechanics that determine a site’s cohesion and hardness (if it is rocky, clay-like or sandy). Each type has the potential to be compressed or fragmented and collapsed. The depth and dimensions for digging a building’s foundation are determined based on these soil types. This study is required in building design and obtaining a permit to begin construction work.
The design stage of the building, according to the shape requirements, determines the structural sequence of construction, meaning the distribution of the building foundations, retaining walls, and the building height. For example, buildings in areas subject to over-6.1-magnitude earthquakes on the Richter scale may not be taller than 20 metres if using traditional construction methods or 49 metres for those with shear walls. Buildings with steel frames can be up to 73 metres tall.
The design for the building’s earthquake resistance undergoes study using static methods (the impact of an earthquake on the base of a building only) and dynamic methods (the impact on the entire structure). For example, if the building is less than 73 metres tall, it must be designed according to static study methods. Those taller than 73 metres must also undergo dynamic study methods.

Only buildings designed according to the above four steps are considered to comply with the earthquake-resistance appendix standards. Engineers and building contractors must apply the building code in their design studies when applying for a construction permit. The Engineers’ Syndicate and local administrative units oversee adherence to the code during the different stages of construction.